Laser Alignment: Is the Laser Perpendicular?
Since there were a few threads on enlarger alignment I thought I'd show this image that explains the how you can tell if your enlarger is out of alignment, or if your laser light is not perpendicular. The people that sell the laser light don't show you this because 'the laser light will always be perpendicular...'
When you take you alignment reading, rotate the laser and watch the reflected beam.
A) If the reflected beam stays centered on the target, this indicates the laser is perpendicular and the baseboard is parallel to the reflecting surface
B) If the reflected beam is not on center and it does not move in relation to the enlarger as the laser is rotated, this indicates the laser beam IS perpendicular and the reflecting surface is NOT parallel to the baseboard.
C) If the reflected beam is not on center and it follows the laser unit as it is rotated, that is, it always reflects back to the same point on the laser faceplate, this indicates that the laser beam is NOT perpendicular and the reflecting surface IS parallel to the baseboard.
D) If the reflected beam is not on center and it follows the path of a circle with a center that does not rotate around with the laser faceplate, this indicates the laser beam is NOT perpendicular and the reflecting surface is NOT parallel to the baseboard. If you adjust the laser beam closer to parallel, the circular path of the beam gets smaller and smaller until it matches condition B. If you align the reflecting surface to be more parallel to the baseboard, the path of the beam will become concentric with the laser orifice and it will approach condition C.
BOTTOM LINE: Good enlarger alignment can be indicated by both diagrams A and C below.