flat field concave imaging gratings?

[Hamish Barker]

I have seen so called "flat field imaging gratings" "aberration corrected concave spectrograph flat field gratings".

http://www.horiba.com/us/en/scientific/ ... -gratings/

could these be applied in astronomical use? they seem to be rather fast f# (2.7) so either a focal reducer on an already fast telescope would be required or other extreme measures if a good f# match.

The simplicity of one optical component does sound appealing! Has anyone tried one?

Cheers,
Hamish

[Robin Leadbeater]

Hi Hamish,

The Starlight Xpress spectrograph uses one (not sure if it is this actual one though)
https://www.firstlightoptics.com/starli ... amera.html
https://www.sxccd.com/handbooks/Handboo ... ograph.pdf
I have not seen any serious results from it (There don't seem to be many out there) but from what I have seen it does show severe astigmatism. Not a show stopper but it must decrease sensitivity to some degree and it would not be any good for imaging spectroscopy. Perhaps it might work better with a cylindrical corrector lens like the UVEX ?

Cheers
Robin

EDIT: I see Horiba claim this one is astigmatism free and can be used for imaging so different from the SX one by the looks

[Hamish Barker]

Thanks robin. I forgot about the sx.