How do you turn your grayscale CCD to a two-color camera? Filters and fun! Here’s a diagram looking down at the dual-viewer setup on my table:
Figure 1. Diagram of setup (viewed from above)
M1 and M2 are mirrors, F1 and F2 are long- or short-pass filters, and DC1 and DC2 are identical dichroics. DC1 reflects short wavelengths and pass long wavelengths, the filters clean up the two paths, the mirrors bring the paths back together, and DC2 combines the two channels. If the channels are offset a little, then short and long wavelengths are split into two copies of the image onto the CCD.
Here’s a pic of the setup:
Figure 2. Picture of the setup with channels drawn
In other words, the dichroics split the green light off the output and move it to a different region of the CCD. You can recombine the two copies and add color using ImageJ, like this:
Figure 3. The right side is an overlay of the red and green channels in false color