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 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 mirror enable it to withstand high temperatures of up to 350 °C, allowing its operation in high-energy lighting systems.
SIR hot mirrors are ideal for heat management in optical systems. They do not heat up as filters based on absorption because they deflect the warm infrared radiation 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. For example, it is often used as a detector trimmer optic 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 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 standard 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 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 hot mirrors 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.
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Thickness (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. |
Note: If you are looking for optics with the reverse functional characteristics of a hot mirror, please visit our cold mirror website. See our SEA-NIR, SEA-UV, and ITO-coatings datasheets if your application needs IR-reflection above the near infrared.
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: January 16, 2025