Heat Absorbing Filters

SCHOTT KG1, KG2, KG3, KG4, & KG5 filter glass

Special Properties

Broadband heat blocking range
Absorbs IR-energy
Transparent for visible light
Almost angle-independent transmissivity
Can be thermally hardened for higher operating temperatures
Largely color neutral
High optical density for infrared radiation

Typical Applications

Heat absorbing glass filters in lighting systems
Sensor technology
Standard IR-absorbers
Heat protection filters
Protective filter for projector optics

Related filters, coatings, and information

SCHOTT Filters (Filters made of SCHOTT color glass)
SIR-Series (Dielectric hot mirrors)
SIR-IR Series (Heat reflection filters with extended blocking range)
SCHOTT-filter calculator (Calculation of filter curves)

Request for Quotation

Heat absorbing filters made of KG1, KG2, KG3, KG4, and KG5 filter materials allow to remove heat energy from an optical system in a targeted manner. Due to their high optical density in the infrared wavelength range, such filters are referred to as heat-absorbing glass. This kind of glass filters is often used in lighting systems to absorb the thermal energy emitted from a light source. While absorbing heat, the glass filters also offer a high, relatively color-neutral transmission of visible light.

Heat-absorbing filters in lighting systems warm up during operation. Therefore, the heat can efficiently be dissipated from an optical system by direct cooling or ventilation of the absorbing filter glass. Whenever heat-absorbing filters must withstand increased operating temperatures, it is recommended to thermally harden the filters after the polishing and shaping processes.

KG-Filters are not only used for lighting applications. Many other optical systems profit from the unique properties of these standard SCHOTT glass filter materials. As the KG-absorption glasses have the advantage of a much more broadband blocking of the infrared wavelength range compared to coated filters (Hot Mirrors) they represent a better solution whenever a wide IR-spectrum should be blocked.

Our high-quality KG glass filters are fabricated from original SCHOTT filter glass which exists as unpolished raw material squares or rolled sheet materials. The heat absorbing filter optics are ground, polished, and shaped to customer's specifications. Please use our inquiry form to request a quotation for your custom-made heat-absorbing filters. For further details and specifications, please email us.

How can I order the heat absorbing filters?

All polished optical glass filters at dimensions up to 50 mm x 50 mm or up to a diameter of 49 mm and at filter thicknesses of 1,00 mm, 2,00 mm or 3,00 mm typically ship within one working week. Other dimensions up to 160 mm x 160 mm are of course possible too.

To get a quotation for a KG-heat absorbing filter, please click the button below:

Request for Quotation

NEW! Our SCHOTT-Filter Online Calculator

Use our online SCHOTT-filter calculator for the analysis of the transmission of all available color glass filters made of SCHOTT filter material. You can use our online calculator free of charge. The calculator allows to compute individual filter transmission curves and to choose to display the internal transmittance or the external transmittance of the glass filters including surface reflection losses. All KG-heat absorbing filters can be analyzed with our SCHOTT filter app.