Test of grating for infrared

These days I tested the grating we will use for separating green and infrared.

I use the holes on the bench to estimate the incident angle. The test are divided by two sorts. For the first one, the incident beam is aligned with the arrow on the grating. For the second one, it is opposite.

I also test it by using a wave plate. It is used to see if polarization can affect the diffraction and if so, how it can affect.