The SGM-TL is an uncooled, inverted SGM produced at PSL. It incorporates precision UHV mechanism design to promote ease of use and accuracy in an economical instrument. The rectangular, open-top chamber is decoupled from the mechanism so that barometric pressure changes do not affect the mechanism's accuracy. Gratings may be scanned under computer control and manually indexed while at any scan angle. Grating fine pitch, fine roll, fine yaw, and elevation may be adjusted under vacuum. Special UHV low-friction bearings designed for zero radial and thrust play are used for the scan angle rotation. PSL built the first of this type of SGM in 1992.

Features