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Infrared filters (IR-filters)
Different versions of IR filters are possible depending on the application
Infrared (IR) filters can have a variety of properties depending on their purpose. One type is the IR transmission filter, which allows infrared radiation, including thermal radiation, to pass through while blocking unwanted radiation in the visible (VIS) and ultraviolet (UV) ranges.
On the other hand, IR blocking filters, also known as IR blockers or infrared cut filters, block infrared radiation, specifically light with wavelengths longer than 780 nm. These filters can be designed to target specific ranges of infrared radiation, such as the near-infrared (NIR) range. IR blocking filters are also referred to as "hot mirrors" and are commonly used in front of image sensors in digital and video cameras to prevent infrared radiation from affecting image quality. IR cut filters are typically interference filters or dielectric (also known as dichroic) filters.
Another type of infrared filter is the thermal protection filter, which reflects IR radiation to reduce thermal stress, often serving as a protective layer for displays or other sensitive components.
Heat protection filters
Heat protection filters, also known as warm light mirrors, heat absorption filters, or "IR cooling glass," are used in technical components to reduce disruptive heat buildup by providing high reflection in the infrared (IR) spectral range. This capability makes them effective at blocking infrared radiation while maintaining high transmission in the visible spectrum. As a result, these filters offer excellent visual transparency without introducing excessive thermal stress into the system.
Heat protection filters are particularly valuable in applications that require light sources with high luminance and significant heat generation. These filters are designed to reflect infrared radiation while allowing visible light to pass through, ensuring that the structure is not subjected to increased thermal load.
We offer custom-manufactured heat protection filters tailored to specific customer requirements. For example, we can design filters to provide high reflection in the near-infrared (NIR) range, effectively blocking heat radiation up to wavelengths of around 1100 nm.
Heat protection filters IR1, IR2, IR3
Heat protection filters are employed in lighting systems to alleviate the thermal burden resulting from infrared radiation. Tailored to the spectral characteristics of the light source, these filters effectively decrease the heating of illuminated objects and mitigate the thermal strain on individuals working under spotlights.
Heat protection filters IR4, IR5
Class IR4 and IR5 heat protection filters are primarily used in surgical lights where high illumination levels and colour rendering are crucial. These filters are specifically optimised to suppress IR radiation emitted by sources such as halogen lamps while maintaining a high colour rendering index. By minimising the heat load on patients, including tissue in the operating theatre, these filters enhance safety and comfort. Simultaneously, they ensure optimal colour reproduction for the surgical team.
We can adapt our heat-reflective coatings to meet specific customer and component requirements, including precise control over optical transmission and reflection values (across selected wavelengths). Additionally, we can fine-tune the edge characteristics (cut-on and cut-off wavelengths) and adjust the reference angle of incidence to suit the application.
Infrared mirror on copper
Copper optical mirrors offer enhanced reflection thanks to dielectric and/or metallic coatings, and are custom-manufactured to meet specific customer requirements. Glass mirrors with a copper coating provide high mechanical stability and effectively dissipate excess heat.
Additionally, copper mirrors offer a cost-effective alternative to mirrors coated with silver or gold, making them a budget-friendly option without compromising performance.
Advantages and applications of infrared filters
Advantages of infrared filters
- Targeted blocking or transmission of the infrared spectrum possible, also adjustable to specific IR ranges such as near infrared (NIR)
- Good options for adjustment to specific wavelengths
- Depending on the filter, high reflectivity in the IR and simultaneously high transmission in the visible range (VIS)
- IR mirror with high reflectivity (98%)
- Reduction of thermal load / temperature load
- Cost efficiency compared to silver or gold
Application examples for IR filters
- Image sensors of digital and video cameras to avoid disturbing influences of IR radiation on the image quality of the sensors
- Infrared drying (e.g. in industrial applications such as the curing of adhesives or drying in 3D printing)
- Thermal protection filters in technical / industrial applications
- Thermal protection filters in lighting systems
- Thermal protection filters in medical technology applications (surgical lights)
- IR laser mirrors
