Telescoping CCD focuser

The CCD needed to be moved 66mm outwards from the spectrograph wall to
be at the 460mm focus point of its Czerny-Turner focus mirror.
After this change, the spectral peaks became razor sharp and 
the numeric processing functions' parameters have to be changed 
to accomodate this new sharpness. The scalloping/sawtooth problem
however still persists and needs to be isolated...




Strip plot- Neon spectrum


(click on image to enlarge)

632.8nm HeNe laser line is marked with a blue line. The Raman notch filter is currently centered just to the 
right of that line so Neon peaks in that area are attenuated or absent up to about 150cm⁻¹ 



(click on image to enlarge)

This Neon plot is without the Raman (Rayleigh) filter. The 633nm Neon peak is more clearly visible.
The 640nm Neon line was also attenuated by the Raman filter. It's Raman shift is 187cm^-1 which is 
further out than desired. The Raman filter's notch can be somewhat adjusted and should be moved 
closer to the laser line. The expected minimum resolvable shift is 150cm^-1 but I think I have
pushed it closer on occasion. The problem with this Raman filter is that it seems to be old and
its optimum angular position has shifted out of convenient mechanical range of the mount.
This presents a problem if the other OEM filter (785nm) cannot be simultaneously mounted on the turret
with the same angle.  The whole turret might need to be scrapped and replaced by a more conventional
configuration. This type of Raman filter has been nothing but trouble. Every small change in the 
beam line has required numerous other changes to compensate because of this filter 
which is operates as both a dichroic beamsplitter and a Rayleigh filter. 
Supposedly this dual-purpose filter can resolve lower Raman shifts
but there are other methods that are probably much easier to maintain: