This is a certified precision Bausch & Lomb optical grating. Much of the following information was taken from the nomenclature label fixed to the back of the grating substrate.

Grating size - 30 x 30 mm, 10mm thick
Focal length - infinity
Grooves / mm - 2000
Blaze angle - 20 degrees
Catalog number - 35-63-04-190
Coating - Al (?)

This grating appears to be in very fine condition and includes a special protective plastic cover. It is marked 'EUV Grating' on the box.

Photo set 1657