everything is off. I put a pass-green/reflect-red mirror at a
45 degree angle with the
green beam going through the
middle. I marked the holes,
then drilled and screwed the
mirror bracket to the
mounting board. The red laser
is mounted so that it aims at
Now, the adjustment
screws can aim the red laser
at the spot where the green
laser goes through, and then
the mirror’s adjustment screws can be used to line up the
dots projected on the wall or paper. The beam’s spots on
the mirrors are difficult to see at this low
intensity, so I didn’t wear the safety glasses for
As mentioned, extra caution should be
exercised for where the beams will hit so that
they don’t make contact with a shiny surface.
With everything screwed down, careful
placement will have the beams directed down
where they won’t hit anyone’s eyes.
Once you’re sure a beam can’t bounce
directly into an eye, there is a slightly brighter
setting that will help to see it better. Breathing
on the mirror will fog it up and allow you to
see where the beam is hitting. I placed the
blue-reflect mirror in the same manner. All
three beams are now aligned.
Once the glass disks are fastened onto the
motors, a cover (Figure 8) should be in place
so that everything inside is shielded from view.
A final focusing and aligning of the mirrors
can be done while looking at the patterns on
the wall. After the beams were aligned in the
mirrors, alignment adjustments are made only
with the mirrors, and not the lasers. Focusing
the laser on the glass disk is different from
focusing at a distance. The intensity is set at
dim with all lasers on (Program 13). A cover
over only the glass disks protects your eyes
from what bounces off the back of the disk.
A laser test circuit (Figure 9) was made to
get some of the details ironed out on how the
lasers worked. It’s not essential for this project,
This circuit is shown near the main circuit in Figure
May/June 2018 45
■ FIGURE 10. The circuit diagram.
■ FIGURE 9. The laser tester.