Product Description
This is a very unusual item. It consists of two components. The first is a rotary graduated mounting with a keyed sleeve. The second part is a calcite prism polarizer (appears to be a Nicol type) in a sleeve with an index for correct orientation in the graduated mount.
I am not sure of a manufacture date, but I would hazzard a guess it was either the 1960's or 1970's. The assembly is in very fine condition. Rotation is very smooth, and there is a vernier reading to 6 minutes of arc in either direction. The outer scale is numbered in degrees from 0 to 90 to 0 to 90 back to 0.
Dimensions of the assembly are as follows.
4.75" outside diameter of fixed graduated support
1.375" bore with clamping collar on upper side (with scale) for reception of accessories. This is the bore that rotates along with the vernier. I believe accessories for this may have included such items as Babinet compensators.
1.250" bore on the lower tube which carries the cell with the prism polarizer.
3.00" overall length including the polarizer.
Prism dimensions are roughly 0.75" on the diagonal and appoximately 1.5" long. The prism is in excellent condition - no bubbles or degradation of the cement layer. One face may be covered with a glass cover slip, but I am uncertain about that. That face is flawless. The other face clearly does not have a coverglass and at the very corner of the prism there are a few flaws, but they are only at the very corner. This is a very nice prism
Gaertner is a highly regarded US manufacturer of metrology equipment including research optical benches, alignment telescopes, measuring microscopes, cathetometers, and ellipsometers. Past production programmes included elaborate monochromators, research spectrometers, and goniometers. It is possible this item was an accessory to a spectrometer.
Location MB 30-4
Photo set 260