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Final calibration
Well the Littrow is almost there. Just "tuning" the slit and grating alignment and found that it's a bit more fiddly than the Classic. The alignment of the collimated beam reflected from the grating is critical. The spectrum also tends to be slanted across the field of view, so if it's not corrected a zero image may be exactly on the centre of the CCD but the red image could be moved outside the pixel area of the CCD.
My grating is inclined at about 2.2 degrees to the axis of the collimator and I found I needed to "rotate" the grating on the mount support clockwise by 0.52 degrees to reduce the movement on the CCD from Zero to Red to within 0.1mm.
Also changed the grating to the Optometrics 1200 lpm and get about 0.55 A/ pixel with the Canon 350D, FWHM of 0.9A giving a resolution of R= 6005.
I'm about to order a 2400lpm grating to increase this resolution to R = 12000, this will give enough resolution to see the fluctuations in the Ha emission lines in the EB stars ( Eclipsing Binary).
Need a small 12V DC to 240V AC convertor; about 5W capacity. That way I can safely use the Neon from a 12V battery. Anyone seen anything like this? I've got a circuit diagram if anyone can build it ($$) for me.
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