Filters picture


Hot mirrors

Special Properties

  • High and neutral optical transmissivity
  • 100% dielectric coating design
  • Very high infrared reflection up to 1100 nm
  • High operating temperature range (up to 400 °C)
  • Works the opposite way of dichroic cold mirrors

Typical Applications

  • Color neutral and efficient separation of
    thermal energy and light
  • Optical reflector for infrared laser diodes
  • Heat filters for light sources
  • Optical CCD-filters for camera chips
  • Sensor- and measurement applications
  • Automotive lighting technology
  • Detector trimmer optics
  • Heat reflection mirror in lighting systems
  • Eye-tracking optics
  • Laser injector devices
  • Projectors

Request for Quotation

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Hot mirrors are dichroic heat-reflection optics which can filter out heat energy from a light beam. This is done by reflecting infrared light and simultaneously transmitting the visible spectrum. A hot mirror is based on the opposite function principle of a cold-mirror. Since it reflects infrared light and because it filters the infrared wavelengths out of the beam path like a filter it can be referred to as "heat reflection filter" as well as to "heat reflection mirror". Both terms are correct.

CNC-shaped SIROur SIR offers a decisive advantage over ordinary heat-reflection coatings or absorbing filters. Their optical transmission of visible light is higher and more neutral in color, while the thermal radiation in the near infrared up to 1100 nm is reflected significantly more efficiently.

Because of its 100% dielectric design and the temperature-resistant quality BOROFLOAT® substrates, the SIR mirrors withstand a high thermal load. The filters can be operated at temperatures of up to 400 °C which allows the use in lighting systems. Furthermore, an SIR mirror does not get as hot as heat absorbing filter optics, because the warm infrared radiation is reflected back instead of being absorbed.

But there are also purely optical applications for our SIR hot mirror. For example, the SIR can work as a detector trimmer in front of a digital camera chip. This prevents the optical image sensor from saturation caused by near infrared light for which many CCD camera sensors are very sensitive.

The non-metallic coating design makes the SIR mirror resistant to thermal load and humidity. The coating is optimized for maximum possible transmittance of visible light and at the same time for maximum achievable reflectivity in the NIR-range. The angle of incidence the SIR hot mirrors are designed for is 0°. However, if a slight shifting of the cut-off wavelength is acceptable, already our standard SIR mirror can also be used at 45°. With this angle most of the visible spectrum is still transmitted and the reflected IR-image keeps a good optical imaging quality. Hence, the SIR mirrors are often found as optics in eye-tracking-systems or in IR-laser injection systems without modification. This can reduce the cost compared to a customized optical coating drastically, especially if only small quantities are needed. If you want to utilize our SIR mirror at incidence angles that differ from 0° please send us an inquiry by email or simply open our support form to ask for further information. Typical optical transmission curves of our hot mirrors when operated at 45° or at other angles of incidences can be obtained on request.

Please take into account that all of our heat reflecting mirror coatings can be modified regarding transmittance and reflection wavelength ranges. Same applies to the optical cut-on and cut-off filter-wavelength and for the angle of incidence. Please use our custom optics inquiry form to conveniently request a quote for custom coated hot mirrors. You are invited to contact us by email for help, further information, and more details.


To receive a quotation for our SIR hot mirrors with individual dimensions please click the button below:


Request for Quotation



SIR, optical transmission curve

View optical transmission curve of our SIR hot mirrors

Product Code

  • SIR hot mirror


  • Temperature resistant BOROFLOAT,
    substrate density 2,2 g/cm3 (25 °C)

Other substrate materials available on demand


  • 100% dielectric multi layer mirror / filter coatings
  • Designed for an angle of incidence of 0°
  • Customized cut-on and cut-off wavelength per request

Operating Temperature

  • up to 400 °C

Optical Flatness

Surface Quality

  • typ. 80-50 scratch & dig (MIL-0-13830A)
  • Other on request

Standard Thicknesses

Other Properties

  • Adherence according to MIL-C-675 C (tape test)
  • Abrasion resistant according to MIL-M-13508 C

Note: If you are looking for an optical mirrors with reverse functional characteristic, please take look at our cold mirror web site.


All given details and specifications are mean reference values and are not guaranteed. In addition please consider our "Notes on technical specifications"