Stab in the dark, but looking at the last picture there appears to be some colour bands. Could this be a diffraction grating?
Not looked at any schematics, but I guess this is potentially what determines what wavelength of laser is being pointed in there before feeding back into the circuitry for the readout?
Have you tried shining a white light source on/through the 'glass' to see if it diffracts?
Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.”... Douglas Adams 1952 - 2001