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Heat Absorbing Filters

Filters made of SCHOTT KG1, KG2, KG3, KG4 & KG5 heat absorbing glass


Special Properties

  • Very broadband blocking range
  • Absorbs infrared energy
  • Transmits visible light
  • Transmittance is independent of angle of incidence
  • Can be thermally tempered
  • High thermal stability
  • High density for infrared radiation

Typical Applications

  • Heat absorption in lighting systems
  • Sensor technology
  • Absorption of infrared radiation
  • 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. They glass filters are mainly used in lighting systems to absorb heat, which is emitted from a light source. At the same time, the filters offer a high, relatively neutral visible light transmission. The filter optics can heat up during operation due to the absorption of heat energy. The heat can then be removed from the illumination system by cooling or ventilating the glass filter. When a heat absorbing filter must withstand high operating temperatures, it is highly recommended to thermally temper the filter glass, after it has been polished and shaped. Our KG-glass filters are fabricated of original SCHOTT raw materials. These raw filter materials come as unpolished raw filter squares or as unpolished rolled filter glass materials. All filters are ground, polished and shaped to customer's specifications. Please use our inquiry form to request your custom made filter.


How to order the filters

All filter dimensions at 50mm x 50mm and smaller and at 1mm, 2mm or 3mm typically ship within 1 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 is online and at your free disposal. Using our calculator, you can compute individual filter transmission curves. You can 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 200-1100nm

Show internal transmission at 1000-4600nm

Product Code

  • KG1-KG5


  • Original SCHOTT KG1-KG5 glass filter raw material


Thermal Tempering

  • min. thickness for full filter tempering = 3mm


  • 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

  • 164mm (square filters)
  • 150mm (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"