Bausch & Lomb (B&L) 35-53-06-89  Precision Grating, 150 Groove / mm, Excellent Condition

I do not recognize the grating holder that is fitted to this Bausch & Lomb precision grating. Much of the following information was taken from the nomenclature label fixed to the back of the grating substrate.

Grating size - 55 x 55 mm
Focal length - infinity
Grooves / mm - 150
Blazed angle - 36 degrees, 52 minutes
Catalog number 35-53-06-89
Part number 350-9-3-1
Coating - Al (?)

The grating has a small scratch very near one edge. It also has a 'zoned' appearance that seems to be the way it came from the factory. Overall appearance is very fine.

Photo set 1653