This is part of my holography apparatus... It was looking cool.

There are three lasers on the left, red (closest to the camera), blue, green (furthest from camera). The red beam is going from left to right, there is a red dot on the left where it is. The two black things on either side of the aluminum bar with the holes hold dichroic mirrors, which pass a long wavelength, but reflect a short wavelength. The first one merges in the green beam (pass red, bounce green), the second one merges in the blue (pass red, green, bounce blue). There is then a beam splitter off camera right, which bounces a beam to a spatial filter which is the bright thing on the right. The two rotating stages (with degree marks) hold half wave plates which rotate the angle of polarization, which changes the ratio of the beam splitter individualy for each wavelength.