D-644  ADJUSTABLE REFERENCE MIRROR
Enlarges autocollimator effective aperture Gives large mirror coverage on a small mounting base Usable in either horizontal or vertical position Flatness certified traceable to NIST

Model D-644 transfer mirrors are used when two or more surfaces are too far apart to be aligned and must be observed through a single autocollimator with reasonable aperture size.  The cost of autocollimators with an aperture large enough to cover a comparable area are exorbitant, but this function can be performed inexpensively by aligning one moderately priced autocollimator to the large D-644 reference mirror.  By sharing the aperture of the autocollimator, the D-644 allows any number of optical surfaces to be aligned within 1 arc second by simply repositioning the autocollimator.

These rectangular mirrors also find use when space is too limited for the larger base and diameter of a mounted circular mirror.  The D-644s have bases less than 4 inch (102 mm) square.  Exceptionally fine azimuth and elevation screws (120 threads per inch) provide precise adjustment when positioned either horizontally or vertically.

Model D-644-101: Coating on front surface only.

Model D-644-106: Both sides coated and plane parallel to 1 arc second or better.

Specifications: