Whether scanner, IR transmitter, infrared camera ...
we will find the optimal optical filter
One of the primary goals in the development of image processing components or HMI (Human Machine Interfaces) is to achieve the best possible image contrast. Attempting to increase system performance in this regard by upgrading the "lighting" or "lens" components can significantly increase the cost of such a system. However, when the spectral characteristics of the object to be imaged are taken into account, it is found that optical filters can improve image quality with minimal impact on other design elements.
Transmission curves define optical filters
There is a range of filter types that are essentially defined by the structure of their transmission curves. Optical filters are devices that selectively transmit light of different wavelengths. Usually a glass or plastic window is installed in front of an electronic display or in the beam path. The panes are either dyed or coated to achieve the desired properties.
An optical filter can selectively transmit light in a specific wavelength range (colours), blocking or eliminating all other colours.
Ready to get specific?
Stephan Zuber
executive director
All kinds of optical filters - finding the right one for every application
The following types of optical filters in particular are used in industrial applications:
- Absorbent
Absorbent filters are made of glass, PMMA or polycarbonate, to which various organic or inorganic additives have been added. These additives absorb the light of certain wavelengths while tranmis others. - Monochrome
Monochromatic filters made of colored glass, acrylic or polycarbonate allow light transmission only in a very narrow frequency or wavelength range (only one color).
ttv offers a wide range of colour filters for use in front of electronic displays
In cast acrylic (LUXACRYL®, ANTIFLEX-AC®) and Polycarbonate).
- Infrared
The term "infrared filter" can be ambiguous, as it can be used for filters that transmit infrared light (and block other wavelengths / visible light) or absorb or reflect infrared light and transmit visible light.
When we talk about IR filters in our product documentation, it is always the former, i.e. filters that transmit infrared light and block the visible part of the light. (see LUXACRYL-IR)
Laser scanners and sensors require reduced light reflection, increased transmission and elimination of ambient light influences in order to optimize measurement and reading results. Likewise, open measuring and sensor units can be exposed to mechanical loads or aggressive substances that can have a lasting negative effect on their function.
ANTIFLEX®-2MC-AFP (crystal clear or in various shades of red) offers the perfect solution for high-quality scanner glass with maximum transmission and lowest residual reflection. This is precision cast acrylic with a multicoating on both sides that provides very low residual reflection and maximum transmission without compromising contour sharpness.
In addition, ANTIFLEX®-2MC-AFP is hard-coated on both sides with surface hardness increased to about 6-8 H. The front side has an anti-fingerprint coating to reduce fingerprints and facilitate cleaning.
ttv offers one of the world's largest portfolios of optical filters (glass, acrylic and polycarbonate) and most likely the right solution for the requirements of your specific application, too.
Ready to get specific?
Stephan Zuber
executive director
Frequently asked questions:
When do I need an optical filter?
Optical filters are useful, sometimes even required, if you want to improve the optical properties of an electronic display or HMI. This can be an improvement in terms of contrast, scratch resistance, glare and reflections, EMC or ambient light shielding, etc.
How do I find out what kind of optical filter is suitable for my application?
Our product portfolio is very extensive and we recommend that you contact us regarding your application-specifics so that we can define a tailormade solution.
What types of optical filters are there?
Our acrylic glass filters can be divided into two large groups: LUXACRYL is a shiny / glossy material and ANTIFLEX-xx is a diffuse matt or optically anti-reflective material. In more detail, a distinction is made between further material properties.
How can I install or attach an optical filter?
There are basically the following options for installation:
- Liquid adhesives (e.g. silicone) via flange milling
- circumferentially applied adhesive frames made from common double-sided transfer adhesive tapes, e.g. from 3M
- Screwing or clamping via drill holes, also with countersinks
- Ultrasonic welding on acrylic surfaces without hard coating.
Which material is suitable for infrared applications?
All acrylic glasses are transparent up to a wavelength of approx. 2000 nm (except when colored white). The color determines the point at which transmittance or transmission is given. LUXACRYL®-IR, a black colored acrylic glass, is suitable for pure IR applications. This blocks the visible wavelength range, but offers transmission in the near IR range up to approx. 1800 nm. LUXARYL-IR can also be produced with an optical anti-reflective coating (multicoating). This increases the transmission to over 98% in the near infrared range up to approx. 1100 nanometers.
Which cover lens do you recommend in front of scanners and sensors?
Our ANTIFLEX®-2MC-AFP offers the highest possible transmission (>98%) combined with the lowest possible reflection (<0.5% per side) to increase the accuracy of sensors and scanners and to minimize interferences.
For wavelengths > 630 nm, we also offer red-coloured ANTIFLEX-2MC-AFP to minimize visible light interference in particular.Is a UV filter the same as an optical filter?
Our acrylics, by definition, contain a UV blocker, thus making it UV-stable and at the same time providing UV protection and weather resistance. The use of LUXACRYL® provides protection against UV radiation for the areas behind it. A UV filter is therefore also an optical filter.
What is the best way to clean optical filters?
The best way to clean our materials and optical filters made from them is with a soft cotton cloth and alcohol (isopropanol). It is also often sufficient to lightly dab and wipe with a soft cotton cloth. Under no circumstances should a microfiber cloth or paper towel be used for sensitive plastic surfaces, as these quickly lead to scratches.