Temperature compensated laser focusing optics

A laser source assembly, comprising:

• a housing having an interior space with a length extending between first and second ends, said housing being made of a first material;
• a first unit comprising a focusing lens mounted within said interior space near said first end;
• a second unit comprising a source of laser light mounted within said interior space in spaced relationship to said first unit;
• a spacer mounted within said space so as to extend between said first and second units and engaging both units so as to prevent relative lengthwise movement therebetween, said spacer being made of a second material having a lower coefficient of expansion than said first material;
• wherein an outer surface of the spacer and an inner wall surface of the housing are concentric over at least a part the length of the housing including the length segment extending from the first unit to the second unit;
• a resilient element mounted in said housing so as to exert a lengthwise force on said spacer, urging it towards one of said first and second ends;
• said housing being a case having a chamber formed by an inner wall for housing a subassembly constituted of said two units and said spacer therein;
• and
• a second means for preventing said subassembly from moving relative to said case in a first longitudinal direction, comprising a shoulder formed on said inner wall of said case and a lateral protrusion formed on said spacer for engaging with said shoulder, thereby preventing said spacer from moving relative to said case in said first longitudinal direction.