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Coatings Corner

What is a Thin Film Optical Coating?

 

Thin film optical coatings are applied to optical substrates such as glass to alter or change its optical properties. The coating is applied in extremely thin layers to the surface and the number of coatings and the thickness of the coating is done to effect a specific wavelength of the light. Thin Film Optical Coatings from Abrisa Technologies are applied via electron beam and ion-assisted electron beam deposition influencing and controlling reflectance, transmittance, absorbance and resistance.

 

Thin Film Optical Coatings include:

 

  • Indium Tin Oxide (ITO)
  • Index-Matched Indium Tin Oxide
  • Front & Back Surface Mirrors
  • Dichroic Filters
  • Band-pass Color Filters
  • AR – anti-reflective Coatings
  • Beam Splitters
  • Metal Coatings
  • Precision Hot Mirrors
  • Cold Mirrors
  • Neutral Density Filters
  • Infrared or IR Filters
  • Ultraviolet UV Filters

 

The thin film multi-layer coatings can be applied to glass substrates as thin as 70 microns and as small as 0.1” and as thick as 6” and in diameters up to 36”.

 

Click Here for additional Thin Film Coatings capabilities.

 

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Solid colored glass has many popular uses

 

Generally used for architectural projects, entertainment lighting and landscape lighting, the soda-lime or borofloat based glass can be heat strengthened for additional resistance to thermal shock. The glass can be machined, screen printed, sandblasted and fabricated to virtually any shape or size.

 

Abrisa Technologies carries a large inventory of MR11 (1.370”) and MR16 (1.965”) diameter and 1/8” thick lenses in stock. For a quote Click Here.

 

Soda-Lime Glass:

 

Abrisa Technologies Red #201 – Used to project a primary red colored light. Holiday/Theme lighting or dramatic effects.

 

Abrisa Technologies Yellow #203 – Vibrant and warm, excellent for special effects and accents. Great for landscaping.

 

Abrisa Technologies Pink #205 – This pale pink color is good for toning, and can be used to pull out the red and rich color of wood, while eliminating a green cast.

 

Abrisa Technologies Deep Green #206 – A dark yellow green or primary green, this is perfect for holiday lighting and special effects.

 

Abrisa Technologies Medium Amber #207 – Primary Amber. Used in landscape lighting often to bring out the color in brick, stone, rock landscapes. Also used for creating sunsets, candlelight or eliminated unwanted blue light.

 

Abrisa Technologies Medium Blue #209 – Good for non-realistic night skies or creating dramatic effects. Can be used as a primary blue.

 

Abrisa Technologies Blue Correction #211 – Used in landscape lighting as a correction filter. Makes the green in foliage “pop”. Also used for moonlighting. Helps maintain white light and eliminate amber hues. Cool area light.

 

Abrisa Technologies Lavender #401– Can be used for color correction or to bring out the reds or browns in wood.

 

Abrisa Technologies Mercury Vapor Green #402 – Used in landscape lighting to duplicate the output of a mercury vapor lamp. Brings out the green in foliage.

 

Abrisa Technologies Light Amber #403 – Warm Pale Yellow. Create fire effects or bring out the warm colors in brick, stone, “rockscapes”.

 

Borofloat Glass:

 

Abrisa Technologies Red #PS20 – Used to project a primary red colored light. Holiday/Theme lighting or dramatic effects.

 

Abrisa Technologies Amber #PS15 – Warm golden amber. Create special effects, candlelight, sunlight and firelight.

 

Many additional lighting products are available. For a complete list of Abrisa technologies absorption filters and dichroic filters and Roscoe reference numbers, Click Here.

 

Metallic Mirror Coatings

 

Abrisa Technologies can deposit a wide variety of precious and non-precious metals onto glass substrates depending upon the application requirement. Metal mirror coatings are often used in systems where a very broadband reflector or beam splitter is needed.

 

Metal coatings can also be an excellent choice when an economical coating is especially important. Examples of common metal coating applications include telescope mirrors, neutral density filters, and general purpose laboratory mirrors.

 

Metals commonly deposited by Abrisa Technologies include aluminum, chromium, silver, gold, and Inconel. Other metals, semi-conductors, and alloys are available, contact our ZC&R Coatings for Optics division for more information: (800) 426-2864.

 

Standard mirror coating specifications are detailed below:

  • Protected Aluminum – Wavelength range (400 – 700nm) and reflects an average of > 85% rover the visible spectrum. Used for applications in the visible or near-infrared.
  • Enhanced Aluminum – Wavelength range (450 – 650nm) and provides >93% reflectivity. A multi-layer film of dielectrics on top of the aluminum enhances the reflectance in the visible and ultraviolet regions.
  • Protected Gold – Wavelength range (700 – 2000nm) and reflects an average of 97%. This coating is best-suited for applications requiring high reflectance in the near-infrared and infrared regions. IR wavelength bands 3-5nm and 8-12nm.
  • Protected Silver – Wavelength range (500 – 800nm) and provides >98% coating offers excellent reflectivity in the visible and infrared regions. It is used for broadband applications. Best suited in low humidity environments to reduce tarnishing.

 

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What is Heat Absorbing Float Glass?

 

Heat Absorbing Float Glass (HAFG) is designed with the capability to typically absorb 40% of the infrared (IR) light and about 25% or more of the visible light that passes through it. The glass reduces solar heat while maintaining visible light transmission. The soda lime glass is a light blue/green color which subdues brightness while providing high visible light transmittance of up to 77% for a glass that is 6.0mm thick. Heat absorbing float glass is often used as a shortpass (SP) filter.

 

A shortpass filter is an optical interference or colored glass filter that attenuates longer wavelengths and transmits or passes shorter wavelengths over the active range of the target spectrum (usually UV ultraviolet and visible region). Learn More

 

Common uses include fluorescence microscopy and in dichromatic mirrors and excitation filters.

 

To learn more about Heat Absorbing Float Glass, Click Here

 

Hot Mirror vs. Cold Mirror

 

Hot and cold mirrors “heat control filters” are types of dichroic filters used to remove unwanted energy from a light emitting source.

 

A hot mirror is a dichroic filter that reflects 90% of near infrared (NIR) and infrared (IR) light while transmitting up to 80% of the visible light. Hot mirrors transmit the shorter wavelengths and reflect the infrared energy. Hot mirrors can be specified for an angle of incidence ranging from aero to 45 degrees. . They are made by applying a multi-layer dielectric coating to the glass substrate such as Borofloat® borosilicate glass. Learn more

 

A cold mirror is a dichroic filter that reflects up to 90% of the visible light spectrum while allowing transmission of infrared wavelengths IR and near IR of up to 80%. Cold mirrors reflect the shorter wavelengths and transmit the heat (infrared). A cold mirror can be specified for an angle of incidence ranging from zero to 45 degrees. They are made by applying a multi-layer dielectric coating to the glass substrate such as Borofloat® borosilicate glass. Learn more

 

Abrisa Technologies provides these heat control filters in thicknesses of 1.1mm, 1.7rmm and 3.3mm in sizes of up to 24” in diameter.

 

What is a Neutral Density Filter?

 

A neutral density or ND optical filter reduces or modifies the intensity of all wavelengths or colors of light equally, therefore providing for no changes in the hue of the color rendition. Neutral density filters can be colorless or clear, or they can be grey in tone.

 

For photography, the purpose of a ND filter is to reduce the amount of light entering via the camera lens, preventing overexposure of images. The filter allows for a longer exposure times than would otherwise be possible. The longer exposure time may allow the photographer to emphasize motion in the image taken. ND filters also enable larger apertures, producing a shallow depth of field.

 

What is a UV Filter?

 

A UV blocking filter or ultraviolet optical filter prevents ultraviolet light transmission. UV filters are commonly used in photography to reduce the level of ultraviolet light that strikes the recording medium. Historically, photographic films were mostly sensitive to UV light, which caused haziness or fogginess, and in color films a bluish hue. Therefore, as a standard, a UV (blocking) filter was used, transparent to visible light while filtering out shorter ultraviolet wavelengths. However, newer photographic film and digital cameras are highly insensitive to UV wavelengths.

 

Overexposure to UV can cause skin and eye damage requiring windows and other glass surfaces to be used for protection. Similarly, UV exposure can also damage artwork, documents, and other ink based items found behind UV blocking glass generally found in museums.

 

Abrisa Technologies generally uses borosilicate glass; Borofloat® as the filter medium and the standard thickness is 0.125” (3.175mm), custom thicknesses are available. The UV filter size can be as large as 24” or (609.6mm) in diameter.

 

For a complete description of all Abrisa Technologies UV Filter options, click here.

 

Anti-Glare vs. Anti-Reflective Glass

 

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Anti-glare or non-glare glass

Ideal for outdoor or high ambient light applications

 

AR Coated GlassNon-glare glass is manufactured by acid etching one or two surfaces of the glass, providing uniform evenly diffused surfaces for high resolution applications. Non-glare glass disperses reflected light, allowing the user to focus on the transmitted image. Non-glare glass is available in several quality and etching levels: from picture frame quality to display quality, and from 60 to 130 gloss units.

 

The lower the gloss reading, the more diffuse the glass panel surface is. The more diffuse the panel surface, the less glare the viewer sees. However, an inverse relationship exists between the degree of diffusion and the panel’s resolution.

 

Features of non-glare glass:

  • Low reflection, high resolution, superior durability and anti-newton ring
  • “Low-Sparkle” grade available for aviation display, military and other high tech display
  • Can be heat tempered, laminated or chemical strengthened
  • Does not become highly reflective as a result of oily fingerprints like anti-reflective coated glass or untreated surfaces
  • For quality assurance, gloss values measured by Gardner Glossmaster 60º
  • Available from 60 gloss to 130 gloss units
  • Can be etched on one or both surfaces

 

Typical Applications:

  • Electronic Displays
  • Cover Screens – monitor face plates
  • LCD Displays
  • Computer Screens
  • Projection Monitors
  • Advertising Panels – outdoor electronic monitors & systems
  • Touch Screens
  • Medical Instrumentation
  • Ruggedized Displays
  •  

    Anti-reflective coated glass

    Excellent for all types of ambient lighting and increases transmission which can reduce necessary power output of LEDs and other displays

     

    Anti-glare GlassAR glass is a glass that has been optically coated on one or two sides to diminish reflections and increase the light transmission, to reduce surface glare and increase substrate transmission and brightness offering better contrast definition by reducing surface reflection over a specific wavelength range. Ghost images and multiple reflection can be minimized and possibly eliminated by applying an AR coating on the glass surface.

     

    Abrisa Technologies AR coatings are all dielectric single or multilayers and are designed for low reflectance and high transmittance in the UV, visible and near IR spectral bands.

     

    Features of anti-reflective glass:

    • High transmission & low reflectance
    • Abrisa Technologies can AR coat customer-supplied glass optics or fabricate from our existing stock of anti-reflective coated glass
    • Large format AR-coated glass readily available (contact factory for stock availability)
    • Contrast enhancement for sharp, clear graphics and text
    • Standard broadband AR reduces surface reflection from 4% to less than 0.5%
    • Can be used in conjunction with conductive ITO coatings, bus bars, UV rejection coatings and surface enhancement coatings (index matching available)
    • Can be custom designed to meet your wavelength requirements
    • Anti-Smudge coating can be applied over AR to reduce “fingerprinting”
    • Hydrophobic topcoat can be applied to eliminate moisture buildup

     

    Typical Applications:

    • Electronic Displays
    • Optics for LED lighting
    • LCD Displays
    • Front Panel Displays
    • Thin-Film LCD Heater Panels
    • Instrumentation Windows
    • Lighting
    • Telecommunications
    • Architectural Windows
    • Display Cases
    • Storefronts
    • Projection Port Windows
    • Sight Glass

     

    Oleophobic vs. Hydrophobic Glass Coatings

     

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    Oleophobic (anti-smudge) coatings on glass and ceramic surfaces create an oil resistant, anti-fingerprint surface that is impervious to dirt, dust, oils, and other particulates resulting in a surface that is easy-to-clean and maintains a cleaner surface longer than untreated glass. Oleophobic coatings are well-suited for projected capacitive (PCAP) and capacitive touch screens, handheld devices, teleprompters, virtual reality applications, and more.

     

    Hydrophobic coatings do not allow water to bond with the surface of the glass. The coated surfaces of the glass become water-resistant, repelling water, dust, oil, dirt and a host of aqueous solutions allowing for easy cleaning of the substrate. Abrisa Technologies’ water repellant hydrophobic coating is an organic film that does not degrade or delaminate over time. The coating can be applied for optics applications with wavelengths between 250nm and 2,700 nm. The rugged coatings comply with MIL-C-575C for severe abrasion. The hydrophobic coating can be provided in either a coated or laminated process and is ideal for touch screen applications.

     

    Abrisa Technologies can provide Oleophobic and Hydrophobic coatings on glass substrates from 01.mm to 25mm thick. The coatings can be applied in conjunction with other Abrisa Technologies coating and fabrication processes for highly customized optics solutions.

     

    CleanVue pic copy
    CleanVue™ PRO when bonded to Abrisa Technologies’ proprietary AR coating has proven to be rugged and durable, and has a low coefficient of friction, providing protection against scratching. Abrisa Technologies’ extensive tests concluded that the product’s oleophobic and hydrophobic water-repelling characteristics did not breakdown or degrade after steel wool, cheese cloth, and MIL-C-675C severe abrasion eraser testing. The coating can also be applied to glass substrates and select coatings for enhancement to their hydro/oleophobic properties.

     

    Click here to see data sheet: CleanVue™ PRO – PRO-AR399

     

    What is a Dichroic Filter?

     

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    Dichroic Filters
    A dichroic filter, thin-film filter, or interference filter is a very accurate color filter used to selectively pass light of a small range of colors while reflecting other colors. By comparison, dichroic mirrors and dichroic reflectors tend to be characterized by the color(s) of light that they reflect, rather than the color(s) they pass.

     

    Dichroic filters use the principle of thin-film interference, and produce colors in the same way as oil films on water. When light strikes an oil film at an angle, some of the light is reflected from the top surface of the oil, and some is reflected from the bottom surface where it is in contact with the water. Because the light reflecting from the bottom travels a slightly longer path, some light wavelengths are reinforced by this delay, while others tend to be canceled, producing the colors seen.

     

    color correction filter
    Dichroic color filter coatings are an excellent alternative to dyed plastics and glass when a beam of light must be split into two distinct beams varying by wavelength.

     

    Dichroic and color correction filters have the advantage of reflecting unwanted light instead of absorbing the energy, which allows dichroic filters to be used with much higher intensity light sources up to 550°F.

     

    Dichroic glass coating/filters can be utilized for heat control (UV & IR) blocking, as soft and spread lenses, and for color correction.

     

    Dichroic filters from Abrisa Technologies are primarily used in such applications as:

     

    • LED color correction
    • Special effects (photography)
    • Entertainment (stage & theatrical lighting)
    • Architectural lighting systems – mood and cosmetic enhancement (color correction) add warmth or cooler atmosphere depending upon the environment desired. For instance restaurant lighting – a warm dichroic filter is used to enhance food and atmosphere while a jewelry store would use a cool filter to enhance sparkle and shine of the gems.
    • Museum
    • Retail
    • Restaurant
    • Casino
    • Residential
    • Outdoor
    • Landscape

     

    Dichroic filters can be utilized for heat control (UV & IR) blocking, as soft and spread lenses, and for color correction.

     

    Available types of dichoic filters offered by Abrisa Technologies include:

     

    • 45º reflective dichroic – (beam splitter) – Beam Splitter (BS) is a term used to describe various coatings which divide a beam of light into separate beams. Dichroic filters are often called beam splitters. In this section, we will be describing beam splitters that divide light at each wavelength of interest into two separate beams.
    • Additive & subtractive color filters – (blue, red, green, cyan, yellow, magenta, orange)
    • Longpass (Trim Filter or LWP) – Long pass filters block a select band of shorter wavelengths. This example, long wave pass cutoff filter provides average reflectance more than 99% from 400-700nm, 50% cutoff point at 750nm ±10nm and 95% transmission from 780-1200nm.
    • Shortpass (Trim Filter or SWP) – Short pass filters block a select band of longer wavelengths. This example, short pass filters block a select band of longer wavelengths. Short wave pass cutoff filter passes light from 325-450nm and blocks visible light from 500-700nm. It has a 50% point at 470nm ±10nm.
    • Bandpass – These filter coatings transmit varying wavelength bands, which are determined by two cutoff wavelengths. Filters can be made at any given wavelength from near ultraviolet to near infrared.
    • Notch (Minus) Filter – Notch filters block a relatively narrow band of wavelengths between shorter and longer pass bands.

     

    Advantages of Dichroic Filters:

     

    • Much better filtering characteristics than conventional filters
    • Ability to easily fabricate a filter to pass any band pass frequency and block a selected amount of the stop band frequencies (saturation)
    • Because light in the stop band is reflected rather than absorbed, there is much less heating of the dichroic filter than with conventional filters
    • Much longer life than conventional filters; the color is intrinsic in the construction of the hard microscopic layers and cannot “bleach out” over the lifetime of the filter (unlike for example, gel filters)
    • Filter will not melt or deform except at very high temperatures (many hundreds of degrees Celsius)

     

    Abrisa Technologies has over 160 different color filters available. Dichroics are offered from 1.1mm (.043”) thick up to 3.3mm (1.28”) thick.

     

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    Display Glass Capabilities

     

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      Glass/Substrate Materials
      Coatings
      Screen Printed Graphics
      Glass Machining/Modifications
      Bus Bars & Wire Soldering
      Protective Coatings & MIL-Spec Tests

       

      Bus Bars & Optics

      A bus bar is a strip of conductive material applied to the surface of a conductively coated glass, most commonly ITO (indium tin oxide) or IMITO (index matched ITO) coatings. Bus bars are screen printed onto an exposed surface of the coated glass; Abrisa applies bus bars either by thin film deposition of chrome-nickel-gold or by screen printing. The conductive nature of these materials makes them excellent bus bars.

       

      The primary function of a bus bar is to conduct electricity. Typical bus bar applications for optics include heater windows and EMI Shielding.

       

      In the case of IMITO coatings, we need to expose the ITO so that the bus bar can be applied directly to the conductive ITO coating.

       

      For more information contact: info@abrisatechnologies.com

       

      Optical Filters – Color Temperature Orange (CTO) and Color Temperature Blue (CTB)

       

      Optical filters are a great tool for a wide variety of lighting applications. One common use of optical filters includes changing the correlated color temperature of a light source. For example, changing the appearance of light from a tungsten lamp so that it looks more like daylight; or, changing light from a flash lamp to look more like light from a tungsten lamp. The class of optical filters used to make these types of color changes are called Color Temperature filters.

       

      The term color temperature comes from the natural phenomenon of colored light emitted by warm objects. Very warm objects, such as a candle flame, emit deep red and orange light. The temperature of a candle flame is roughly 1500K. If you increase that temperature the light emitted begins to look more blue. An example that comes to mind is a piece of hot iron worked by a blacksmith. A hotter fire heating the iron will cause the iron to glow increasingly with a blue hue. The blue appearance of the iron indicates that the temperature of the metal is up above 6500K.

       

      Of course, optical filters don’t really change the temperature of the object emitting the light. We are able to achieve our magic by using color temperature filters to remove some of the light of wavelengths of our choosing. So for example, we can use a filter to absorb or reflect away some of the orange and red light emitted by a tungsten lamp. This makes the remaining light look more blue and results in a higher correlated color temperature. Conversely, we can use a filter to remove some of the blue light emitted by a flash lamp making the remaining light look more orange and having a lower correlated color temperature.

       

      Fortunately these color temperature filters have been standardized. There are two types typically supplied by Abrisa Technologies. These two types are Color Temperature Orange (CTO) and Color Temperature Blue (CTB). Each type is also divided into a few different standard values indicating the amount or degree of color temperature shift they induce. A Full CTO is specified to have a color temperature shift that changes a 5500K color temperature to approximately 3200K. The other standard CTO filters supplied by Abrisa Technologies are 1/8, 1/4, and 1/2 CTO. Respectively, these shift a 5500K light source down to approximately 4900K, 4500K, and 3800K.

       

      A full CTB filter does just the opposite and shifts 3200K up to 5500K. Other standard values of CTB include 1/4 and 1/2. The 1/4 CTB filter shifts 3200K up to approximately 3500K. And the 1/2 CTB filters shifts 3200K up to approximately 4100K.

       

      Standard Abrisa Technologies color temperature filters are supplied on Borofloat® glass substrates in sizes as large as 24″ in diameter. Standard and custom sizes are available. Additionally, we are happy to provide custom filters for your color application.

       

      For more information contact: info@abrisatechnologies.com

       

      PHYSICAL VAPOR DEPOSITION – Sputtering vs. Electron Beam Evaporation

       

      Physical Vapor Deposition (PVD) is a family of processes that is used to deposit layers of atoms or molecules from the vapor phase onto a solid substrate in a vacuum chamber. Two very common types of processes used are Sputtering and Electron Beam Evaporation.

       

      Sputtering process involves ejecting material from a “target” that is a source onto a “substrate” (such as a silicon wafer) in a vacuum chamber. This effect is caused by the bombardment of the target by ionized gas which often is an inert gas such as argon. Sputtering is used extensively in the semiconductor industry to deposit thin films of various materials in integrated circuit processing. Anti-reflection coatings on glass for optical applications are also deposited by sputtering. Because of the low substrate temperatures used, sputtering is an ideal method to deposit metals for thin-film transistors. Perhaps the most familiar products of sputtering are low-emissivity coatings on glass, used in double-pane window assemblies. An important advantage of sputtering is that even materials with very high melting points are easily sputtered while evaporation of these materials in a resistance evaporator or Knudsen cell is difficult and problematic

       

      Electron Beam Evaporation (commonly referred to as E-beam Evaporation) is the process used at Abrisa Technologies, the ZC&R Coatings for Optics division. This is a process in which a target material is bombarded with an electron beam given off by a tungsten filament under high vacuum. The electron beam causes atoms from the source material to evaporate into the gaseous phase. These atoms then precipitate into solid form, coating everything in the vacuum chamber (within line of sight) with a thin layer of the anode material. A clear advantage of this process is it permits direct transfer of energy to source during heating and very efficient in depositing pure evaporated material to substrate. Also, deposition rate in this process can be as low as 1 nm per minute to as high as few micrometers per minute. The material utilization efficiency is high relative to other methods and the process offers structural and morphological control of films. Due to the very high deposition rate, this process has potential industrial application for wear resistant and thermal barrier coatings aerospace industries, hard coatings for cutting and tool industries, and electronic and optical films for semiconductor industries. Additionally, coating uniformity and precise layer monitoring techniques are also some advantages with this process.

       

      For more information on Physical Vapor Deposition, please visit the link below for further reading:

       

      http://en.wikipedia.org/wiki/Physical_vapor_deposition

       

      Written by: Ace Perez (08/23/12)

       

      For more information contact: info@abrisatechnologies.com

       

      UV Blocking Glass Benefits for Dental Curing Lights

      Dental curing lights utilize coated glass filters, such as a UV blocking glass, to selectively emit specific bands of light. These curing lights are used to polymerize dental composites, sealants and cements that are often used to help repair or replace tooth material.

       

      During the tooth repair or replacement process, these composites are applied to the damaged area and sculpted to resemble the missing portion of tooth. At this point the Dental curing light tool is positioned and activated to emit the precise band of light that causes the composites to polymerize and harden. Afterward, other tools are used to grind, scrape and polish the material so that it properly resembles the original tooth.

       

      Originally, when these dental curing lights were invented, they were designed to emit UV light which interacted with the composites used at that time in order to polymerize them. Over the years since then it was discovered that there are composites which react to blue light in much the same way. Due to health concerns that go along with UV exposure to vulnerable tissue in the mouth, this new method was implemented.

       

      In the original design, the dental curing light utilized coated glass filters that would selectively reflect some of the light emitted from the lamp contained within the device. When these optical filters are properly angled and sufficient venting is utilized in the device, the desired band of light is directed toward the emission end of the tool and the undesired bands are directed away so that they do not interfere with the application. In the original design a UV blocking glass was used to direct the desired UV band toward the emission end of the tool. In the current designs for these devices it is likely that a UV blocking glass is used to direct the harmful UV radiation away from the emission end of the tool.

       

      Another difficulty discovered through the use of these tools is the incredible amount of heat generated by the lamp itself, but also by the composite material undergoing polymerization. In some rapid curing systems it has been noticed by Dental professionals that the polymerization process alone generates enough heat to be uncomfortable to the patient and sometimes it is enough to damage surrounding tissue. One way to limit the amount of heat exposure the tissue is experiencing is to utilize a UV blocking glass with an IR reflecting hot mirror. In combination with a band pass filter, the device would emit far less energy and the vulnerable tissue in the mouth would be less likely to overheat and become damaged.

       

      Through utilization of UV blocking glass filters, dental curing lights have made it much easier for dental professionals to provide realistic tooth repair and replacement solutions to their clients.

       

      To learn more about ZC&R’s UV blocking glass or to discuss how it may benefit your specific application, call 800.426.2864 or email us.

       

      UV Blocking Glass Solutions for Color Correction
      and Scattered UV Elimination in Photography.

      When dealing with any kind of photography, you are always dealing with light of some form or another. Photography by definition is the act of capturing an image on film or digitally through a lens or an aperture. Modern photography has become so precise and so amazingly beautiful that stunning images have really become the norm. However one of the challenges that photographers have still not been able to completely eliminate with technology, no matter how expensive the camera, is the effect of light that does not fall within the visible spectrum.

       

      Ultraviolet light is a significant factor when dealing with unfiltered light. While our eyes cannot see it, the camera does. What we refer to as visible light is light radiation that falls between 400 nm and 700 nm. When you look at a rainbow you can see the spectrum of visible light where the shorter wavelengths of light closer to 400 nm are blue and the longer wavelengths of light closer to 700 nm are red. When you look at the red and blue edges of a rainbow, you should notice that the color seems to fade a bit the farther out you go. This is not because the light isn’t there, it’s because your eyes aren’t capable of seeing those wavelengths.

       

      rainbowColor film photography presents an interesting problem when it comes to UV light. Color film essentially has three color sensitive layers, one of which is blue. The blue layer responds to blue light, but it also responds to UV light. When taking color film photographs in an area with unfiltered light, outdoors for instance, then you run the risk of overexposing the blue layer and ending up with photographs that have a distinctive blue tinge. Our eyes and brains tend to be trained not to see this blue tinge when we are used to seeing it, but then you see a photograph that doesn’t have it and it’s like seeing the world through new eyes. Using a UV blocking glass while taking color film photographs will drastically reduce the blue tinge effect.

       

      Digital Photography doesn’t really have the same problem that color film photography has, and while that is good news for digital camera users, there are still other problems to be resolved. One such problem is called “scatter”. This effect is most noticeable when photographing distant subjects and shows up as a bluish haze that reduces the crisp clarity often sought when photographing subjects like mountain ranges or cityscapes. Another difficulty with digital photography in relation to UV is “purple fringing” or PF. This most commonly occurs when a dark subject is backlit on a bright background, such as tree leaves against a clear sky. UV blocking glass filters also help to alleviate this problem.

       

      There are other ways to alleviate all of these problems, either through photo manipulation after the fact, or by limiting your choices of subject matter to studio scenes where the light can be filtered at the source. In all of these alternatives, you are limiting the quality and choice of subject matter and not truly solving the problem of ultraviolet light filtering. The best pictures are taken with equipment that solves the problem up front so that quality of the photograph is not adversely affected in development or touch up.

       

      To learn more about ZC&R’s UV blocking glass or to discuss how it may benefit your specific application, call 800.426.2864 or email us.

       

      Using UV Blocking Glass to
      Protect Liquid Crystal Displays

      Liquid Crystal Display (LCD) technology and display quality continues to evolve, while prices for LCDs have declined dramatically in the last few years. These two factors have helped to increase demand for LCDs in a variety of new and challenging applications, such as outdoor displays, where environmental conditions such as high ambient light and heat build-up can affect display quality. This has created a need for unique solutions to help extend the lifetime and display quality of LCDs in these conditions. One such solution is the use of UV blocking glass.

       

      LCDs utilize organic components that are susceptible to ultraviolet degradation, which can manifest as a shift in color or a washed out look. Displays used in outdoor environments or in close proximity to Fluorescent black lights and other long wave UV emitters are at considerable risk of Ultraviolet degradation. Outdoor LCD devices are at high risk, but with more indoor UV emitter applications being developed it has become apparent that sunlight based ultraviolet radiation is not the only concern. Indoor UV emitter applications are being developed or are currently in use by medical and forensics groups for example.

       

      The atmosphere itself blocks a significant portion of sunlight Ultraviolet radiation up to 280 nm, which is the top end of the UV C range. Oxygen is the primary element responsible for the atmospheres filtering effect on UV C. Indoor UV C emitters are in relative close proximity to the LCDs they would potentially affect and thus are not likely to benefit as much from the filtering effects of the atmosphere. UV C is also damaging to people and so high intensity emitters use protective barriers to contain the UV C radiation. For this reason, LCDs within the application would need a protective UV Blocking Glass.

       

      UV B is less blocked by the atmosphere, but is still significantly blocked by ordinary glass (although this is not generally true for Silica or quartz glass). In situations where an application uses UV B radiation, it is recommended that the application be sealed to prevent excessive human exposure. Any application that needs an LCD to be exposed to UV B radiation regularly should utilize a UV Blocking Glass coating to ensure that the LCD does not degrade.

       

      While ordinary glass blocks a significant portion of UV B this still leaves a significant portion of the UV A range that permeates the front of an LCD. It is this UV A range that has often eluded efforts to prevent ultraviolet degradation. Its effects are often not as obvious, but can be seen in many everyday situations where carpet, drapes or other natural and synthetic polymer objects are left in a window for long periods of time. They fade, crack or disintegrate due to the unblocked UV A radiation that passes through ordinary glass.

       

      ZC&R’s UV Blocking Glass solutions act as a mirror to ultraviolet radiation. In combination with a hot mirror (IR Reflector), this coating helps preserve the performance of an LCD exposed to unfiltered broadband lighting while retaining the visibility and clarity of the display.

       

      For more information on ZC&R’s UV Blocking Glass solutions please call 800.426.2864 or email us.

       

      Using UV blocking glass to prevent skin and
      eye damage from entertainment or medical lighting.

      Throughout the past few decades, it has been established that people are being damaged by ultraviolet light from the sun, and so we are being encouraged by the medical industry to take protective measures to limit the effect the sun has on our skin and eyes. UV blocking glass is one such way we can protect ourselves from ultraviolet light damage as well as isolating UV light for specific uses.

       

      There are certainly other ways to protect us from low intensity ultraviolet light and new products come out all the time that offer this protection in various ways. Vast amounts of research and effort have been put into finding out just how dangerous UV light damage is and how to prevent it. Lotions, glasses and even clothing have been developed to prevent the carcinogenic effects of UV light exposed to our skin and eyes. These protection are effective when the source of the ultraviolet light is the sun, but what do you do when the sun is not the source?

       

      While the sun is widely recognized as the most significant source of UV light it is not the only source we must work to protect ourselves from. Ultraviolet light is known to emanate from many different man made sources like high pressure arc lamps and fluorescent lamps as well as incandescent lamps and solid state light sources (LED’s, OLED’s and PLED’s). In fact it is known that broadband or “white” light sources are almost guaranteed to produce at least some UV light along with the visible light intended.

       

      Among all the light sources that we use just to see the world around us, there are also light sources that are used for other purposes. For a while now, Medical research and care facilities have been using light to treat patients as well as conduct experiments. One such treatment is light therapy used on the skin of someone who has acne vulgaris or a child that has neonatal jaundice. Other skin conditions that can be treated specifically with UVA (315 – 400 nm) or UVB (280 – 315 nm) light are psoriasis and eczema. Light therapy is also used by directing light into the eyes in order to help treat circadian rhythm disorders such as delayed sleep phase syndrome and can also be used to treat seasonal affective disorder. Another medical application for light is during surgery, where light from a high intensity arc lamp is funneled to the surgical site through optical fibers. It is critical to use UV and IR filtering in this application so that the unprotected internal tissue is not damaged by the light needed to see what the surgeon is doing.

       

      Other medical uses for ultraviolet light are for protein analysis through UV-visible spectroscopy, DNA sequencing, drug discovery and medical imaging of cells. Through these applications, UV light becomes a valuable resource and a tool for accomplishing important tasks that not only help researchers find the source of health problems, such as errors in DNA but UV light is also being used to help correct health problems through development of new drugs and other medical technologies. In all of these tasks it is important that the UV light be contained or isolated through the use of UV blocking glass.

       

      Just like fire and many other forces harnessed for use as tools, ultraviolet light must be used with knowledge, caution and protection. While there are many ways to protect ourselves from the damaging effects of UV light, it is most important to recognize that protection is needed. Once that is determined, then the appropriate form of protection can be acquired and implemented. ZC&R’s UV blocking glass is an excellent example of a form of protection that filters the light at the source, or through isolating UV light so that it is directed to the appropriate point of use without adversely affecting unintended tissue.

       

      To learn more about ZC&R’s UV blocking glass or to discuss how it may benefit your specific application, call 800.426.2864 or email us.

       

      How to Protect Museum Quality
      Artwork with UV Blocking Glass

      UV Blocking Glass acts as a mirror with regard to Ultraviolet light wavelengths (400nm and shorter). UV rays are one of the most significant sources of degradation in museum artwork. As such it is a problem that has prompted much consideration. Since artwork is intended to be seen, it is important that any solution to this problem not obscure visible light (400 – 700nm) wavelengths significantly while blocking or reflecting UV light. Adding an Anti-Reflection coating allows greater clarity in the visible light spectrum by helping to alleviate any inherent reflection in the glass.

       

      Many UV Blocking Glass solutions are said to provide a certain percentage of protection from UV light, often ranging between 96% and 99.9%. It is important to note that there are different kinds of UV light and the amount of protection provided for each kind of UV light is as important as its overall protection against UV. UV B and UV C radiation for instance are significantly blocked by regular glass, but UV A radiation isn’t significantly blocked. If an overall rating were given to regular glass it might deceive someone into thinking that their artworks were perfectly fine behind regular glass, when in fact UV A radiation can be virtually unhindered as it passes right through regular glass. Taking this into account means knowing that the UV Blocking Glass you’ve opted to use doesn’t just protect versus UV in general, but is specifically blocking significant portions of the entire range of ultraviolet radiation.

       

      In addition to utilizing UV Blocking Glass it is also important to adhere to the following guidelines when displaying valuable artwork:

      • Use just enough light to display the artwork as intended. Even though implementing a UV Blocking Glass solution, it is important to reduce light levels in the display area because the small amount of UV that does pass through adds up over time. Reducing light levels reduces the amount of UV the artwork is exposed to.
      • Do not expose artwork to direct sunlight. The sun is a significant source of UV B and UV A (most of the UV C and shorter wavelengths are blocked by the atmosphere). It is also a high intensity light source that conveys much higher levels of UV radiation than regular artificial light sources.
      • Use Incandescent, not fluorescent light sources. Fluorescent lights produce much more UV light than incandescent lights do.
      • Other environmental concerns can hazardously affect your artwork as well. Any museum quality artwork should be contained in a controlled environment. Humidity and oxygen are traditional culprits for artwork degradation. In these situations it may be ideal to use a hermetically sealed viewing case.
      • Do not allow the use of flash cameras. The intense and unfiltered light from a flash camera adds up over time. Allowing artwork to be exposed to hundreds of thousands of flashes will likely have a perceptible effect on the piece.

      ZC&R UV Blocking Glass is a high quality solution at a good price. If unique and irreplaceable artwork is to be preserved in a viewing area with minimal exposure to irreparable ultraviolet degradation, then our UV Blocking Glass solution is the right way to go.

       

      For more information on how UV Blocking Glass is used to preserve artwork and museum pieces, please call 800.426.2864, email us or visit our heat control page at abrisatechnologies.com/heat-control/.

       

      What is a Transparent Heater Window?

      Transparent Heater Windows are used for widely differing purposes from keeping food hot or cold to preventing aircraft windows from frosting over. In essence a Transparent Heater Window is a pane of glass with an application of transparent semiconductor coating that has electric current passed through the coating. The electrical resistance of the coating creates heat energy which heats the glass, which then radiates heat.

       

      Transparent Heater Windows were originally developed during World War II for use on the windshields of aircraft. Certain aircraft were deployed to high altitude or cold weather environments and were susceptible to frost forming on the windshield which obscured the vision of the crew.

       

      Several different types of Transparent Heater Windows exist. The most common form can be seen used in the rear window of an automobile as a de-fogger. The obvious flaw in using that particular iteration of the technology is the fact that it has visible lines which can obscure vision. For that reason Transparent Conductive Oxide coatings are used. TCO’s come in several forms, but the three most common are Fluorine-doped Tin Oxide (SnO2:F), Indium-Tin Oxide (ITO), and thin stacks of oxides and metallic silver. ITO coatings are robust and suited for a variety of industrial uses.

       

      Using a TCO in a transparent heater window also has another note worthy property. The metal oxides used not only conduct electricity, but also reflect heat. Without a TCO the glass surface absorbs heat as a high-emissivity material. Adding the coating allows the glass to reflect heat as a low-emissivity material.

       

      Transparent Heater Windows are used in a wide variety of applications today. They are used in supermarket freezers and cold item displays to reduce the amount of environmental heat that reaches the contents while allowing customers to view what is inside. These windows are also used in outdoor security camera housings to prevent frost from forming and obscuring the view of the camera. Please call us to discuss how this technology is, or could be, used in your application.

       

      For more information about transparent conductive oxide coatings or LuxVu Transparent Heater Windows please call 800.426.2864 or email us.

       

      Some ways to improve the
      performance of an EMI Shielding Window.

      Once you’ve determined what kind of EMI shielding window is appropriate for an application, you then have to take into consideration any modifications that may be needed for implementation. One environmental concern that may cause the application to perform inadequately is use outdoors during peak daylight hours. In this situation you have an abundance of ambient light which is likely to reflect off an EMI shielding window to some degree and overpower the light emanating from the display behind the window. This particular window may function as intended for the given application while located in a more controlled environment, but changing the conditions in which the window is used risks changing its performance.

       

      There are many situations where an EMI shielding window may need contrast enhancement. Varying conditions often require different solutions. Several regularly used solutions are; anti-reflection coatings, matte finishes, optical color transmission filters or special laminates such as polarizers. Anti-reflection coatings drastically reduce the amount of light reflected off the window, and allow it to pass through. This can reduce the amount of glare, and increase the readability of the display. Other solutions, such as matte finishes or circular polarizers can be used with varying results.

       

      One concern that may arise with an EMI shielding window is the need to clean it on a regular basis and how that potentially abrasive cleaning process might affect the window. An ideal cleaning process would be one that does not leave residue that might interfere with the windows performance. When using a cleaning process like this for an extended period of time the window may start to degrade from the abrasiveness of the cleaning process. This is more noticeable in situations where an optical coating is used on the viewer side of the window. In this case it may become necessary to use an abrasion resistant coating that would help protect the EMI shielding window from damage while allowing the window to be cleaned and maintained. ZC&R’s LuxVu IMITO films include ion-assisted scratch resistant surfaces for high durability requirements.

       

      For more information about anti-reflection coatings or LuxVu IMITO EMI shielding windows please call 800.426.2864 or email us.

       

      What is an EMI Shielding Window?

      An EMI shielding window is an optically transparent, electrically conductive barrier that significantly reduces the amount of electro-magnetic radiation that might pass through it. These shielding windows are commonly surrounded by non-transparent barriers that are more effective EMI shields, but do not offer the optical transmission needed to allow visible light to pass through the barrier. Between the EMI shielding window and the non-optically transparent barrier there is often a conductive busbar made of a highly conductive coating, such as an epoxy based paint that is highly filled with conductive silver particles, or a deposited metal film.

       

      EMI Shielding Windows are utilized in many different applications that require electro-magnetic separation between two regions while maintaining at least a minimum optical transmission. There are a number of reasons why you would do this. In emergency medical environments where EMI sources are not guaranteed to be denied entry, it is imperative that EMI sensitive equipment be shielded properly to ensure that they function as intended. To prevent equipment malfunction on the battlefield, many different pieces of EMI sensitive military equipment must be shielded from known and unknown EMI sources. Many different kinds of equipment need to be shielded either so that they can be protected from external EMI sources or so that their internally generated EMI does not interfere with external equipment, or cause harm to people.

       

      There are three generally accepted types of EMI shielding windows. The three different types each have their own strengths and weaknesses. There are knitted wire mesh screens, woven mesh screens and transparent conductive coatings. All three types generally use either clear plastic or glass sheets as the substrate. Both the knitted and woven wire mesh screens rely on small diameter wires (between .001” and .0045” diameter) combined with typically 10 to 30 openings per inch for knitted wire mesh or 80 to 150 mesh (wires per inch) for woven wire mesh to determine the optical transmission of the EMI shield. The third type of coating is referred to as an Electrically Conductive Transparent Coating (ECTC) and does not use wires. ECTC’s utilize deposited electrically conductive material onto the surface of an optically transparent substrate.

       

      For more information about EMI Shielding Windows please call 800.426.2864 or email us.

       

      How does a Front Surface
      Mirror help a Rear Projection System?

      Rear projection systems ideally use a front surface mirror (or first surface mirror) instead of a second surface mirror for image clarity.

       

      Image clarity is often determined by taking into account two primary indicators. Amount of ghosting is the first and is a condition where an image is displayed two or more times with the secondary images being offset on the display. The secondary images typically have a decreased intensity. In the case of the use of a second surface mirror the ghosting images are at about one tenth of the intensity of the primary image when the angle of incidence is around 65 degrees.

       

      The second indicator is contrast. This is measured as the minimum light intensity level in the image subtracted from the maximum light intensity level. This is then divided by the maximum light intensity level added to the minimum light intensity level. In essence this means that a projected image with an effective minimum light intensity level of zero and a maximum light intensity level higher than zero will have a contrast ratio of one. As the minimum intensity level becomes brighter, the image’s contrast level decreases and the overall picture quality decreases. If the minimum and maximum levels are the same value, then the contrast is zero and the image will look washed out.

       

      With a first surface mirror, only the aluminum surface on the front of the mirror reflects the incident light. This means that any ghosting produced by the mirror is entirely eliminated and the contrast ratio of the incident light is unaffected by the reflecting surface.

       

      For more information about first surface mirrors and their benefits in rear projection systems please call 800.426.2864 or email us.

       

      What is a Front Surface Mirror?

      First let us define what a mirror is and then we can explain what a front surface mirror is.

       

      A mirror is any specularly reflecting surface, and in most large volume applications this reflective medium is aluminum coating. A back surface mirror has the reflective coating on the surface opposite the viewing surface, so it’s imperative that the substrate be transparent. In most cases the substrate is glass and the aluminum based coating has a protective coating over it that helps to protect it from damage it might receive during transport or installation.

       

      Back surface mirrors are very useful for reflecting light in commercial applications such as a mirror mounted on a wall for personal grooming. These are considered low precision mirrors because they actually have two reflecting surfaces. The first reflecting surface is the initial surface on the pane of glass where a small percentage of light is reflected off the surface. The second reflecting surface is the aluminum coating where a high percentage of light is reflected off the surface.

       

      This dual reflection effect of a low precision mirror causes a loss of contrast and image distortion that is undesirable in high precision applications like rear projection systems, scanners and reflecting telescopes. In these cases good image quality is highly preferred, and this is where a front surface mirror is desired for clarity and single image reflection.

       

      A front surface mirror is similar in construction to the previous mirror described except in a few key ways. The first way is that the reflection coating is on the first surface of the glass pane (or possibly other substrates). The second way is that the reflection coating does not have an obstructive protective coating, but instead incorporates a protective aspect within the reflection coating.

       

      Another key difference is the quality of the aluminum base coating that is used for the reflection surface. Front surface mirrors commonly use a much higher quality material that has a relatively high reflectance across a broad spectral band (visible). ZC&R front surface mirrors not only provide high quality and high reflectance, but are also comparably low cost and durable. ZC&R front surface mirrors pass humidity, adhesion, salt fog and cheesecloth abrasion tests.

       

      For more information regarding Front Surface Mirrors please call 800.426.2864 or email us.

       

      Reduce LCD panel failure
      from excessive IR and UV light.

      One way to help prevent IR and UV radiation damage which causes LCD failure is to implement a hot mirror with a UV blocker.

       

      Before we get into specifics about how this would work, it is important to understand that liquid crystal display panels and polarizers utilize organic compounds that are susceptible to high heat and light energy stress. These organic compounds will eventually break down if deployed in high stress environments. One such contributing factor to LCD panel failure is the use of a high energy unfiltered illuminator. The near IR and shorter UV wavelengths not only add excess heat that may overheat the liquid crystal and prevent them from working properly, but they also add UV band energy that is destructive to organic compounds.

       

      Over time the UV and IR will degrade and damage the LCD panel and polarizers to the point that they produce an unacceptably poor performance. In most applications this is observed to be color shift, washed out images and an observable raise in the darkness levels produced by a damaged LCD panel.

       

      In order to help prolong the onset of such damage a set of UV and IR band filters and mirrors can be used to minimize the amount of harmful energy that is conveyed to the LCD panel from the illuminator. In order to determine what combination of filters and mirrors are best for any particular application it is important to know how each material reacts to the various intensities of bandwidths emitted by your chosen illuminator.

       

      Frequently the Illuminators used in LCD systems are gas discharge lamps such as xenon arc lamps and metal halide light sources. A standard hot mirror that reflects energy between 750 and 1200 nm can be used to mitigate the majority of IR energy being conveyed to the LCD panel. In addition a UV blocker can be used to mitigate the damage from energy below 400 nm.

       

      Other thin film coatings and substrates can be utilized to reduce the IR and UV damage to an LCD panel. Any solution must be well researched to minimize concerns so that a sufficient cooling mechanism is planned and allowed for in the application.

       

      For more information about hot mirror and UV blocker thin film coatings used to protect LCD panels and polarizers, please call 800.426.2864 or email us.

       

      Protect liquid crystal displays from sunlight damage.

      LCDs used in outdoor situations have many concerns to deal with in addition to any that they might normally encounter during indoor use. Initially some concerns are weather related such as moisture in the air or extreme temperatures. Another concern that is often not understood or just not known about at all is sunlight damage.

       

      Liquid crystal displays use organic components that are susceptible to UV (<400 nm) and IR (>750 nm). These bandwidths of radiation have an observable impact on the organic components in LCDs. Extended exposure has been known to cause a color shift and a washed out look to images displayed with the LCD.

       

      Over time the UV and IR radiation degrade the organic components causing them to fail to function properly. The amount of time it takes can vary depending on brand and model as well as specific weather conditions the display has been exposed to. For instance some atmospheric disturbances can reduce the amount of Ultraviolet that is transmitted to the display.

       

      In any case it is important to protect your display from the elements, especially if it is going to be exposed to harsh environments not intended by the manufacturer. One way to do this would be to utilize a Hot Mirror with a UV blocker. This will significantly reduce the amount of IR radiation between 750 nm and 1200 nm, as well as the UV radiation below 400 nm. If the LCD is going to be used outdoors for extended periods then an extended hot mirror may be necessary, which extends the bandwidth protection out to 1600 nm and will help reduce some of the longer wavelength IR damage.

       

      Another concern with liquid crystal displays are their susceptibility to overheating due to excess IR radiation. The LCD is intended to operate within a certain range of temperatures according to the manufacturer’s instructions and outdoor use can lead to higher than normal temperatures. The display being exposed to excessive heat can cause the crystal to become isotropic and fail to perform properly. A hot mirror can help alleviate these concerns as well by reducing the amount of infrared radiation that heats the display.

       

      If you would like to know more about hot mirrors and UV blockers, then please email us or call 800.426.2864.

       

      Hot Mirror applications
      for use with digital photography

      Digital photographers use many filters to achieve varied effects or solve problems, such as using a hot mirror filter to reduce the effect of the near IR on visible light images. One particularly telling issue is taking images of people with a digital SLR. There are several other issues related to near IR bleed, but the most noticeable coloration differences are really the biggest reasons to use a hot mirror filter.

       

      One issue noted by photographers is how infrared radiation can penetrate skin layers a bit deeper than visible light, and then will pick up a blotchy discoloration that the camera interprets in the visible spectrum. The IR radiation can also pick up sub-dermal features such as veins. This particular effect can lead to the need to edit images with software designed for that purpose, but can be quite time consuming. Adjusting these images with software can also lend toward an airbrushed look that is sometimes less than desirable.

       

      Another issue that can be quite cumbersome is how artificial light sometimes gives imagery a greenish tint. This can cause otherwise good pictures to lose their color neutral tone. This is especially noticeable when dealing with white or near white backgrounds within indoor settings. Staged indoor environments like motion film lots or live theater are good examples of situations where a photographer or filmographer might want to reduce the amount of color variance due to infrared bleed.

       

      Essentially solutions for this problem break down into two types, post capture and inline. Post capture solutions, such as software used to “color correct” images are time consuming and often less perfect than desired. These solutions also tend to lead to other problems where desired hues are lost or adjusted in negative ways, such as lips turning paler to match skin color, or eyes turning from hazel to blue while trying to correct for greenish tint. Inline solutions range between high end digital cameras that auto-correct for color variance due to near IR bleed, or lenses that adjust for the color variance. Some of these solutions are better than others, and as technology improves and high end cameras become better at correcting for things like this it becomes less of an issue. Ultimately, preventing the near IR from ever affecting the image in the first place is ideal. This reduces the amount of time and technology needed to prevent this problem. In order to do that you would use a hot mirror filter that blocks the near IR from entering the camera.

       

      ZC&R creates hot mirror filters for just this purpose. Please email us or call 800.426.2864 for more information.

       

      What is a cold mirror useful for?

      Referencing our recent post on hot mirrors can help greatly in understanding how a cold mirror functions as they are both heat control coatings.

       

      Cold mirrors are much like hot mirrors in that they are used to separate IR from the non-IR. The major difference between the two is that cold mirrors transmit IR bands and reflect one or more non-IR bands. As can be seen in our UV Cold Mirror graph, the coating represented is specially designed to reflect more than 95% of UV rays from 350 to 450 nm while transmitting more than 90% between 550 and 1200 nm at 45 degrees angle of incidence. This means that you can use this coating to split a beam and have the longer bandwidths (550 to 1200nm) transmitted while UV rays (350 to 450 nm) are reflected and sent another route. This can help isolate bands that are needed for a particular application while unneeded or possibly harmful bands can be isolated and removed from the application.

       

      One particularly useful application for this kind of dichroic filter we’ve discussed before is in reference to optical fiber. Optical fiber can be damaged by Ultra-Violet and Infra-Red radiation. When a cold mirror is used in conjunction with a hot mirror you can isolate application specific visible light from harmful UV and IR bandwidths such that the visible is transmitted to the optical fiber to be used and the UV/IR are reflected away from the fiber where they will not damage or harm the application.

       

      Cold mirrors are often used in lighting applications where excess heat is not desired and IR radiation is not helpful. In these applications the visible light is reflected to the application and the IR is transmitted away from the application.

       

      For more information about Cold Mirrors and other Heat Control Coatings call 800-426-2864 or email us.

       

      What is a hot mirror?

      A hot mirror is in essence a thin film coating applied to substrates in effort to reflect infra-red radiation either as a means to harness the reflected wavelengths for an application or to remove them from an application.

       

      Hot mirrors are often misunderstood due to their name and understandably so. Judging by the name it would be reasonable to believe that these kinds of coatings reflect heat by reflecting the infrared spectrum. Along that line of thought it would seem that objects illuminated by visible light passing through a hot mirror would be cold, however that is not entirely the case.

       

      It’s true that a hot mirror reflects a significant amount of heat through it’s effect on the infrared spectrum. There is still a measurable amount of heat generated through high energy visible light photons. These shorter length visible light photons actually carry more energy than those in the IR band. This means that if you implement a hot mirror and measured the temperature of the illuminated subject, you would still see a rise in temperature, albeit less of one than if you were to forgo the use of the hot mirror.

       

      So this shows us that it’s not actually heat that they reflect, but the IR band and sometimes the UV band. As demonstrated by our HM-VS-1600 Hot Mirror which specifies that the average transmission is to be more than 85% from 425 to 675 nano-meters (nm) and the average reflectance is more than 90% from 750 to 1150 nm and 80% from 1150 to 1600 nm, but also indicates a high reflectance under 375 nm shown by the graph.

       

      Another aspect of hot mirrors to be aware of is that most hot mirrors are colored a light yellow. This can adversely affect some applications that require the light to be as white as possible. For this reason ZC&R includes color neutral hot mirrors in our standard line.

       

      For more information about Hot Mirrors and other Heat Control Coatings call 800-426-2864 or email us.

       

      Protect Fiber-Optic Cable from UV
      and IR damage with Hot Mirrors and Cold Mirrors.

      How are hot mirrors and a cold mirrors used to prevent UV and IR radiation from damaging fiber-optic cable?

       

      Recently we’ve been getting a few questions about the effects of UV and IR radiation on optical fiber that is often used in high speed local area fiber-optic communications equipment and image displays or lighting systems. So we thought it was about time we shared a basic synopsis of the effects and a few methods by which to prevent unwanted radiation from destroying costly equipment or delaying expensive projects.

       

      It’s important to understand what optical fiber is. Optical fiber is made of either glass, plastic or polycrystalline materials such as quartz and is intended to carry visible or infrared light from one end of the fiber to the other. The optical fiber is coated with a transparent cladding to enhance the refractive index of the fiber and is then surrounded by a buffer and a jacket for mechanical protection. The optical fiber functions by having light emitted from a source, such as a high energy arc lamp, diode laser or LED, coupled into the core of the fiber, which contains and directs the light to the other end of the optical fiber where it can be read as data or displayed as an image.

       

      The various compositions of optical fiber have different strengths and weaknesses. For instance optical fiber used in long distance communication, such as those making up the backbones of the internet, are very likely composed of germanium dioxide doped silica glass, which has the benefit of a lower optical attenuation, but is often very expensive to implement when compared to Plastic optical fiber (POF) due to the special handling and installation techniques required.

       

      Optical fiber has many practical applications from medical surgical headlamps to high end communications channels. For some industrial, medical or sensing applications where larger cores are needed than in standard data communications, a plastic-clad silica fiber or polymer-clad silica fiber (PCS) is used. Optical fiber is used in many different applications, many of which require that the light passing through the optical fiber be as bright as possible. This is often achieved through the use of high energy arc lamps.

       

      The low cost of implementation for POF and PCS make them preferable to glass optical fiber in many different applications. One thing that makes them less preferable is their susceptibility to UV and IR radiation damage. The damage from high energy UV photons takes the form of solarization of the core and/or cladding which can discolor the fiber thus causing signal degradation. Solarization can form physical defects in the fiber which can selectively absorb the visible light spectrum which adversely affect the transmittance efficiency of the fiber. In extreme cases, the fiber core face can be burned, all but destroying the fiber’s functionality.

       

      Quartz and glass optical fibers have an advantage of being more resistant to the effects of UV and IR damage, but are not immune to the effects of high irradiance levels of UV light. While arc sources are the brightest, they are also the most damaging. However, even lower power sources can cause UV and IR damage. There are a few ways to effect the prevention of this damage, but one of the most effective is to use a combination of hot and cold mirrors.

       

      26_G01-682 Standard Hot Mirror_smallHot mirrors can be used to protect the fiber by reflecting the UV and IR wavelengths away from the fiber while transmitting visible light. This will allow most of the desired light to be used in the application while the harmful UV radiation is prevented from damaging the fiber.

       

      23_G01-444 UV Cold Mirror_smallCold mirrors can also be used to protect the optical fiber by reflecting the desired visible light to the fiber and passing the harmful IR wavelengths on to a disposal method. Even better than using just one of these mirrors is to use both, as each kind of mirror is not perfect, using them in conjunction with each-other allows for a greater degree of protection, while retaining the light needed for the application.

       

      One way to achieve the use of a hot mirror and cold mirror is to set the cold mirror at a 45 degree angle to the light source such that the visible light is reflected toward the optical fiber and the IR wavelengths are passed through to an absorptive mechanism or a venting port. Then the hot mirror is placed between the cold mirror and the optical fiber so that the limited remaining harmful UV wavelengths are reflected away from the fiber.

       

      Another method by which the hot mirror and cold mirror can be used is to coat the reflective backing of the light source with a combination coating, causing the IR and UV radiation to pass into the housing where it can be absorbed or vented.

       

      For more information about Hot Mirror and Cold Mirror applications, please call our staff at 1-800-426-2864 or email us.

       

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