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Heat Absorbing Filters KG1, KG2, KG3, KG4 & KG5


Special Properties

  • Very broadband infrared blocking range
  • Absorbs infrared energy
  • Transparent for visible light
  • Almost angle independent transmissivity
  • Can be thermally tempered for higher
    operating temperature
  • Largely color neutral
  • High density for infrared radiation

Typical Applications

  • Heat absorbing filters in lighting systems
  • Sensor technology
  • IR-Absorbers
  • Heat absorbing filters for projectors
  • Projector optics

Glass filters made to absorb thermal energy

SCHOTT KG1 - KG5 heat absorbing filters have a high density for infrared light. The optical color glass filters are often used in lighting systems to absorb heat emitted from a light source. At the same time, the glass filters offer a high, relatively color neutral visible light transmission. The filter optics heat up during operation caused by absorption of heat energy, so it is removed from the illumination-system by cooling or ventilating the glass filter. When a heat absorbing filter must withstand very high operating temperatures, it is recommended to thermally harden the filter glass, after it has been polished and shaped.

Our KG-optical glass filters are fabricated from original SCHOTT raw filter materials which exist as unpolished raw filter-squares or as unpolished rolled filter materials. All heat absorbing filters are ground, polished and shaped to customer's specifications. Please use our inquiry form to request a quotation for your custom-made heat absorbing filter.


How can I order the filters?

All polished optical glass-filter optics at dimensions at up to 50 mm x 50 mm and below and at thicknesses of 1,00 mm, 2,00 mm or 3,00 mm typically are shipped within one working week. To ask for a quotation for a KG-heat absorbing filter, please click the button below:


Request for Quotation



NEW! Our SCHOTT-Filter Online Calculator

Visit our online SCHOTT-filter calculator for the calculation of the transmission of all available color glass filters made of SCHOTT filter material. The calculator is online at your free disposal. You can compute individual filter transmission curves and choose to see the internal transmittance, or the external transmittance of the glass filters including surface reflection losses.




Show transmission of KG1, KG2, KG3, KG4 and KG5
IR-absorbing glass filters at 200-1100 nm

Show internal transmission at 1000-4600 nm


Product Code

  • KG1-KG5


  • Original SCHOTT KG1-KG5 filter glass material


Thermal Tempering

  • minimum thickness for full thermal filter tempering = 3 mm


  • Depending on material and thickness of the filters
  • Other on request

Surface Quality

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

Max. Dimension

  • 164 mm x 164 mm (square filters)
  • ø 150 mm (diameter filters)
  • larger sizes possible at large quantities

Further detailed information about this product is available on request.


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