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FAQs Your question answered.

The most frequently asked questions from our customers.

For any questions not answered here, please do not hesitate to contact us by phone or email.

How do I find the correct SCHOTT glass filter for my application?
  • 1. Select the spectral characteristics for the filter (longpass, shortpass, bandpass, neutral density)    Description: Optical Filter Glass Catalogue-2013, 3.6
  • 2. Define the required wavelength for the application. Which wavelengths should be absorbed and which wavelengths should pass through?
  • 3. Choose the required dimensions (including thickness and tolerances) and the mechanical specification (i.e. unpolished, polished or toughened).


Are neutral grey filters suitable for absorbing visible light in defined steps?

Yes, through the use of neutral density (ND) filters which cover the visible spectrum (400-700 nm).


The filters are available individually or as a set consisting of 16 filters covering the range of optical density from 0.15-5.0 (at 546nm).


ND-filters are additive. For example, when a filter with an optical density (OD) of 1.3 is combined with a filter with an OD of 2.6, you arrive at a final OD of 3.9. Therefore, the standard filter set is able to cover more than 16 steps of OD.

ND-filters are typically designed to work with the wavelength of 546nm. Can other wavelengths be specified?

Yes, within the range 400-1100nm other wavelengths can be specified. However, we are not dealing any more with a standard filter; rather, grey glass with a custom density.


Please note that ND-filters within and especially outside the visible range do not function entirely linearly. This means that we can only guarantee the OD for a specific wavelength (e.g. 1060nm / 546nm etc.)


Due to the production tolerances in the material thickness of +/-0.05mm, there are variances in the expected density / transmission.

Are the optical glass filters described in the catalogue available in different sizes, round or square, >50mm?

Yes, upon request.

Do all glass filters have a chamfer?

Dimensions < 50mm (round or square) are without a chamfer. A chamfer can be applied upon request.


Dimensions > 50mm are delivered with a chamfer as standard.

Does ITOS GmbH supply color glass filters from other manufacturers?

No, as an exclusive SCHOTT AG distributor we only supply their products.

Is the glass in the KG range (i.e. KG1, KG2, KG3, KG5) suitable for use as laser protection glass? Can I build my own laser safety eyewear using these filters?

No, definitely not!


The European standard for laser safety eyewear is defined by EN207/208/60825. Not only is the protection with OD defined, also the laser damage threshold. Protection that is defined by the OD alone is not sufficient. Light absorbing glass filters must in this case be combined with a shatter protection layer.


Should you be looking for protection from laser light, please contact a manufacturer of laser safety eyewear and related products.