Hot Mirrors
Dielectric heat-reflection filters
SIR-Series
Special Properties
- High VIS-transmission
- Efficient heat control and thermal energy blocking
- Designed for an angle of incidence of 0°
- Excellent infrared reflectivity up to 1100 nm
- High color neutrality
- Metal-free layer design
- High operating temperature of up to 350 °C
- Borosilicate glass substrate
- High optical quality
- 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
- Fiber protection filters
- Detector trimmers
- Mirrors for eye-tracking systems
- Laser beam injectors
- Heat control in projectors
Related Optical Components
- Heat Absorbing Filters
(KG1, KG2, KG3, KG4, & KG5) - SIR-IR Series
(Hot mirrors with extended reflection range) - SHD-Series
(Dichroic cold mirror)
Hot mirrors reflect a significant portion of unwanted infrared radiation (IR) while transmitting most of the visible light spectrum. This selective dichroic reflection and transmission capability is achieved through carefully tailored optical coatings deposited on optical substrates. By effectively reflecting the IR wavelengths and allowing visible light to pass through, hot mirrors prevent the excessive heating of target objects or sensitive components within optical systems. Such hot mirrors work based 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.
Our SIR offers a decisive advantage over most standard hot mirrors and heat-absorbing filters. It provides a higher and more color-neutral optical transmittance for visible light, while reflecting thermal radiation in the near-infrared up to a wavelength of 1100 nm significantly more efficiently. The all-dielectric filter design and the thermally resistant borosilicate glass of our SIR hot mirrors enable them to withstand high temperatures of up to 350 °C, allowing their operation in high-energy lighting systems.
SIR hot mirrors are ideal for heat management in optical systems. They do not heat up as much as filters based on absorption because they deflect the warm infrared energy back to the light source instead of absorbing it. This way, the thermal energy is blocked and reflected before entering the optical system.
In addition to the applications described above, there are also purely optical tasks for our SIR hot mirrors. For example, they are often used as a detector trimmer optics in front of digital camera chips to prevent image sensor saturation caused by near-infrared light. Many CCD camera sensors have high sensitivity in this spectral range.
The non-metallic construction makes the SIR hot mirrors resistant to heat and humidity. We optimized the SIR's thin film for the maximum possible visible light transparency and maximum reflectivity in the near infrared range. We conceptualized it for a light incidence of 0°. However, when a slight shifting of the cut-off wavelength is acceptable, the SIR can also operate at an angle of 45°. It then still transmits most of the VIS spectrum, and the reflected IR image maintains good optical quality. Hence, many customers successfully utilize our SIR for eye-tracking or IR laser beam-injection. Using our SIR in such cases can drastically reduce costs, especially if only small quantities are needed because no expensive customization is required. If you want to operate our SIR hot mirrors at an angle deviating from 0°, please inquire by email or via our support form to obtain further information. We are happy to provide the typical curves of our SIR when used at 45° or other angles.
We can customize the SIR in terms of transmission and reflectivity by adding or modifying the coating layers. The same applies to the optics' optical cut-on and cut-off filter wavelengths. Please use our inquiry form to get a quotation for your individually designed custom optics conveniently.
Please choose a thickness from the table or use the button below to request a quotation for our SIR-hot mirrors with individual dimensions.
Specifications
SIR hot mirror
transmittance spectrum for i = 0°
Enlarge the curve to view details
Standard Thicknesses
Please click on a thickness to request a quote:| THK (mm) | Tolerance |  |
|---|---|---|
| 1.10 | ±0.10 | ✔ |
| 1.75 | ±0.20 | ✔ |
| 3.30 | ±0.20 | ✔ |
| Custom thicknesses are available per inquiry. | ||
| The thicknesses marked with "✔" are also possible within 48-hour express manufacturing. | ||
Construction
- Multilayer all-dielectric filter coating
- Designed for i = 0°
- Customized cut-on and cut-off wavelengths per inquiry
Substrate
- Heat-resistant BOROFLOAT® borosilicate glass
with a density of 2.2 g/cm3 (25 °C) - Other options are available on demand
Operating Temperature
- up to 350 °C (with uniform heating)
Optical Flatness
- Depending on glass and thickness
- Defined flatness per inquiry
Surface Quality
- Typ. 80-50 scratch & dig (MIL-0-13830A)
- Other on demand
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 optics with the reverse functional characteristics of a hot mirror, please visit our cold mirror website. Please refer to our data sheets on our SEA-NIR, SEA-UV, and ITO coatings if your application requires reflectivity beyond the near-infrared range.
All data and specifications given are average guide values and are not guaranteed. Moreover, please consider the “Notes on Specifications”.
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Last update: April 28, 2025