An injection locking type or MOPA type of gas laser device which requires only a small installation area and allows easy maintenance. A hook member is adjustably connected to a cam device having a generally smooth half mooned shaped surface that is configured for engagement with a generally flat topped pin that can be alternatively engaged and released so as to allow a desired adjustment of the hook and the cam to be obtained. Non-designated cover cells and other geometric data are flattened into the designated cover cells. The armature and engaging plate engage together when the armature rotates in one direction by a predetermined angle relative to the engaging plate. A video encoder performs corresponding signaling. This invention also relates to an apparatus for adjusting temperature that operates a vapor compression cycle.