I used the SolidSpec3700 spectrophotometer at ATC to measure the transmission spectrum of the Crystalline coating from CMS.

We have 2 samples, one is AlGaAs transferred on a silica substrate and the other one is transferred on a sapphire substrate.

The settings of the instrument are: 

- Slit width = 2nm

- Sampling = 0.5nm

- Range 1400nm - 600nm

- Lamp switch point: 840nm

There are some little differences between the two samples:

- they are shifted by about 3nm 

- silica substrate sample has larger side oscillations