Abstract: A chemical laser including a laser pump which is relativey lightweight with no moving parts is provided. This produces a low pressure, regenerable, closed system for treating laser cavity exhaust gases to remove (i.e., pump) them from the system.The exhaust gases which emerge from the laser cavity of the chemical laser are pumped by reacting them preferably with titanium, titanium-zirconium alloys, zirconium, tantalum, etc. These gases include hydrogen, deuterium and their halides, the halogens, oxygen, CO.sub.2, nitrogen and H.sub.2 O. This obviates the requirements for heavy equipment normally employed to produce a high vacuum in the laser cavity.

Abstract: An optics module for use in a holographic borehole instrument which is operable to determine the stress in the wall of a borehole by recording successively on the same holographic recording medium two holograms of a selected surface region of the wall and, in the interval between the two recordings, drilling a stress relief hole in the wall in stress relieving relation to the selected surface region to produce on the recording medium a double exposure hologram containing holographic information representing the stress. The optics module embodies a frame which adjustably mounts the optical elements of the holographic system of the instrument in a manner which facilitates initial alignment of the system and preserves the alignment during instrument operation.