for mating with notch 63c in head 63b to rotate screw 63 rotation of screw 63 in one direction or the other will move substrate 61 and thus laser diode 7 either toward the lens system or away from the lens system fig7 illustrates in cross section a structure similar to that disclosed in fig1 wherein screw 4 is threaded through support structure 6 rather than through spacer 3 rotation of screw 4 results in laser diode 7 moving away from or toward lens system 1 in the same manner as described above in conjunction with fig1 fig8 illustrates an alternative embodiment of this invention wherein a set screw 4 passes through an opening in support 2 and is threaded through an opening 3a in spacer 3 the end 4a of screw 4 contacts diaphragm 5 and allows diaphragm 5 to be pushed away from lens system 1 thereby adjusting laser diode 7 in the same manner as described above in the embodiment of fig1 and similar structures lens 1 is inserted into opening 2a in lens support structure 2 such that annular flange 1a presses against the bottom surface of support 2 a small amount of an appropriate adhesive such as 34 loctite 34 then firmly secures lens system 1 in support structure 2 fig9 illustrates an additional embodiment of this invention using a screw 4 with differential threads formed thereon in the structure of fig9 screw 4 has a stem of two parts each with a different diameter portion 4d has a smaller diameter than portion 4c portion 4d is threaded with threads having a first selected pitch while portion 4c is threaded with.