Stray Light (Black) Absorbers

For many applications, it is useful to have surfaces that can absorb any light that falls on them. For instance, on the inside of optical instruments, this type of surface would be used to minimize the amount of stray ambient light that reaches an exit slit or optical detector. In the visible wavelength range, this type of surface would look black, hence the name “black” or “stray light” absorber.

Iridian’s stray light absorbers work using the principle of optical interference and can be designed for almost any wavelength range and over different angles of incidence. These coatings are made of metal and oxide materials making them especially robust with low out gassing properties.


Iridian’s black absorbers have been used in space applications for many years to provide high contrast surfaces. In addition, they have been used for the inside of optical instruments to reduce stray light. These absorbers can be deposited onto metal foils, cut up and applied to different surfaces or applied directly onto an optical component and patterned.

Example of black absorber coating with a reflectance < 3.5% from 300 to 1700 nm:

Black Absorber Coating


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