How does the Optical Alignment work?

The GEMINI Interferometer has a 10 mm clear aperture, and the light inside the device propagates in free space. The most efficient way to use the GEMINI is to enter with collimated light in free space. If one uses optical fibers, then it is possible to use fiber couplers before and/or after the GEMINI.
The optical alignment of the GEMINI is straightforward, as you just need to insert it into the beam path in your setup. There are 2 apertures (1 in the input and 1 in the output surface) with variable diameter, in order to facilitate the optical alignment in the center of the clear aperture; once aligned, the apertures should be completely opened to ensure the maximum throughput.