This mirror was removed from a SPEX Czerney-Turner monochromator. It is believed to have a focal length of meter. The mirror diameter is 85mm and is held on an aluminum bracket with adjustments for collimation angle. Focus is achieved using a guide bar within the monochromator housing that fits a channel in the base plate. Motion is imparted to the holder by a special lead screw with a groove that sits in a fixed aperture within the monochromator (see third photo).
Dimensions of the baseplate are 4 inches wide and 5 inches deep. The front mirror surface is approximately 2.5 inches in front of the rear edge of the base. The optic axis is approximately 2.75 inches from the base.
The mirror is aluminum coated, and appears to be free of blemishes with two minor exceptions. There is a very faint smudge near the center of the mirror which we did not attempt to clean (it was too faint to show in the photos), and a very fine hairline scratch in the coating. This is visible just above the hold down clamp in the last photo.