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Hot Mirrors

Dielectric heat reflective coatings


Special Properties

  • High visible optical transmission
  • Efficient thermal energy blocking
  • Designed for an angle of incidence of 0°
  • Excellent infrared reflectivity up to 1100 nm
  • High color neutrality
  • Metal-free coating
  • High operating temperature up to 360 °C
    (with uniform heating)
  • Borosilicate glass substrate
  • Reverse operating principle of dichroic cold mirrors

Typical Applications

  • IR cut filters for CCD camera chips
  • Heat protection filters for light sources
  • IR-reflective optics in lighting systems
  • Mirrors for IR-laser diodes
  • Measurement and Sensor Technology
  • Lighting applications in the automotive industry
  • Detector trimmers
  • IR-reflector optics for eye-tracking systems
  • Laser injectors
  • Heat-filters in projectors

Related filter optics

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Hot mirrors are dichroic filter optics that remove thermal energy from a light beam by reflecting IR-light and simultaneously transmitting the visible spectrum. Such optics base on the opposite optical function principle of cold mirrors. Since they reflect infrared light and filter it out of the beam path, they are called hot mirrors, heat-reflecting filters, or heat reflection mirrors. All these designations are correct and customary.

CNC-shaped SIR hot mirror

Our SIR offers a decisive advantage over most standard hot mirrors and heat-absorbing filters. It provides a higher and more color-neutral optical transmission of visible light while it reflects the thermal radiation significantly more efficiently in the near-infrared up to 1100 nm. The all-dielectric optical coating design and the thermally resistant BOROFLOAT® substrate glass of our SIR hot mirror enable it to withstand a high temperature of up to 360 °C allowing the operation in high-energy lighting systems.

SIR mirrors do not get as hot as filters based on absorption because they reflect the warm infrared radiation to the light source instead of absorbing it. This way, the thermal energy is blocked and reflected before it can enter the optical system.

In addition to the applications described above, there are also purely optical tasks for our SIR. For example, it is often used as detector trimmer optics in front of digital camera chips to prevent the image sensor from saturation caused by the near-infrared light. Many CCD camera sensors have a high sensitivity in this spectral range.

The non-metallic optical coating construction makes the SIR resistant to thermal load and humidity. We optimized the SIR's thin film for maximum possible optical transmission of visible light and maximum reflectivity in the NIR range. We conceptualized the SIR for a light incidence of 0°. However, in cases a slight shifting of the cut-off wavelength is acceptable, our standard SIR can also operate at an angle of 45°. It still transmits most of the visible spectrum at this incidence, and the reflected IR image keeps a good optical imaging quality. Hence, many customers successfully utilize our SIR mirrors for eye-tracking and IR laser beam-injection applications without modification. Using our standard hot mirrors in such cases can drastically reduce costs, especially if only small quantities are needed because no expensive customized coating is required. If you want to operate our SIR mirrors at an angle deviating from 0°, please send us an inquiry by e-mail or via our support form to obtain further information. We are happy to provide typical optical transmission curves of our hot mirrors when used at 45° or other angles.

Please note that we can adapt all of our optical hot mirror coatings regarding transmittance and reflection ranges by adding or modifying coating layers. The same applies to the optical cut-on and cut-off filter-wavelength of the optics. Please use our inquiry form for custom optics to conveniently request your individually designed optics.


To get a quotation for our standard SIR-hot mirrors with individual dimensions, please choose a thickness from the thickness table or click the button below.


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48h-Express Service for customized optics, logo Also available in 48 h Express-Service


SIR hot mirrors
transmission spectrum for i=°0

SIR, optical transmission curve
Enlarge curve to show details

Standard Thicknesses

(Please click on a glass thickness to request a quote)

Thickness (mm)


48h-Express Service
1,10 ±0,10
1,75 ±0,20
3,30 ±0,20
Custom thicknesses on request
The thicknesses marked with "" are also possible within 48–h Express Service.

Coating Construction

  • Designed for an angle of incidence of 0°
  • All-dielectric, multilayer filter coating
  • Customized cut-on and cut-off wavelength per inquiry

Glass Substrate

Operating Temperature

  • up to 400 °C (with uniform heating)

Optical Flatness

  • Depending on glass thickness
  • Defined flatness per inquiry

Surface Quality

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

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 optical mirrors with reverse functional characteristics, please visit our cold mirror website. If your application needs IR mirrors, please see our SEA-NIR, SEA-UV, and our ITO-coatings datasheets. ITO with higher film thicknesses is capable of reflecting infrared light.


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

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