N-BK7 and special glasses

Standard substrates


Transmission curve of N-BK7®
Transmission curve of N-BK7®

Low expansion glasses

If applications require low thermal expansion and FS will be too expensive, commonly the following materials are used: Boro­float®, Duran®, Pyrex® (Corning 7740). Glass materials with a thermal expansion coefficient lower than FS and close to zero are for example ULE® (Corning 7972) or Zerodur®. But all glasses have a limited transmission range (see table "Characteristics of the most common substrates").

Glasses with special refractive index

LASEROPTIK can supply all sizes of nearly all common substrate materials, like all types of flint glass or crown glass. For these normally we use optical glasses from Schott, Ohara or Hoya. On customer request we can of course also work with the material of other manufacturers. We can for example provide a refractive index between nd = 1.487 (S-FSL5) and nd = 2.00 (S-LAH 79).

Optical filter glasses

We can also supply and/or coat on optical filter glass (mainly from Schott), which works as na­tural filter, for example as band-, long- or short-pass filter. A number of different colorants and concentrations can be provided on request.