Goal: Make the 2 dots shot from the middle-left and the middle-right overlap.
1. Take a piece of double-sided tape and put it on the metal ring in front of the third mirror.
2. Move the laser head to the mid-left position manually. Close the door and press "Laser Pulse".
3. Open the door and check the position of the dot. This dot shot from the middle-left corner is the reference point when adjusting the mirror. The shot made on other positions should be adjusted to move toward the reference point.
4. Move the laser head to the middle-right position manually. Close the door and press "Laser Pulse".
5. Open the door and check if the second dot is overlapping with the first one on the same position. If not, adjust the screws behind the first mirror.
If the dot shot from the middle-right corner is not found on the tape, it means the optical path is very much misaligned. Please try the middle-middle position instead of the middle-right position. Make sure the shots of the middle-left and the middle-middle can overlap and then go back to the original middle left and middle-right adjustment.
6. The screws behind the second mirror control the mirror angle which shows in the picture below. Release the nut on the screw, rotate the screw for the desired direction and test the shot position until the two shots can overlap. Tighten the nut slightly back to its position when the adjustment is done.
7. Put on a new tape and run the test again.