Aligning the Mirrors...

start without a lens near the laser.

Here is the same picture, enhanced:

Adjust the side mirror until the two

brightest dots are coincident.

Then place the lens in the lens holder.

Here is the same picture, enhanced:

The micrometer on the side can be used

to measure the change in position of the

back mirror. The units are in hundreds of microns.

The micrometer is currently

indicating a position of:

 1 + 0.5 +0.13 = 1.63 (x 100 microns).