Reflecting defraction grating

[Merlin66]

I'm looking for a 1200 l/mm reflecting grating, minimum 25 x 25, prefer 40 x 40mm. Only one I can find so far is from Edmunds and looks VERY expensive.

Anything available in Australia?? I can trade plus difference for similar glass gratings.

[Stu]

I'll get you one. What are you using it for?

[Merlin66]

I've built a couple of spectroscopes using 1200 lpm gratings based on an old BAA design and now want to uprade to a Littrow design based around a 200mm photographic lens, similar to the WPO design of Maurice Gavin. This design really needs a 40 x 40mm reflecting 1200 lpm grating.

See http://www.astroman.fsnet.co.uk/newspec.htm
and http://users.erols.com/njastro/faas/