BragGlass™

Absorption spectrum of BragGlass™

Proprietary technology of high efficiency diffractive optical elements manufactured at OptiGrate is based on a linear photosensitivity in a BragGlass™ (so-called photo-thermo-refractive or PTR glass) which is a silicate glass doped with cerium, silver, and fluorine. The precipitation of a minor crystalline phase after UV-exposure and thermal development induces a refractive index change to create a holographic phase pattern throughout the whole glass volume.

BragGlass™ properties:

• Photosensitivity ranges from 280 to 350 nm
• Transparency from 350 to 2700 nm
• Absorption in the near IR region below 0.0001 cm-1
• Refractive index 1.49
• Abbe number 60
• Photo-induced refractive index increment up to 1200 ppm
• Spatial frequencies from 0 (zero) to 10,000 mm-1
• Phase pattern cannot be erased by any type of optical or ionizing radiation