flat field concave imaging gratings?

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Hamish Barker
Posts: 226
Joined: Thu Jun 20, 2019 12:11 am

flat field concave imaging gratings?

Post by 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
Posts: 1926
Joined: Mon Sep 26, 2011 4:41 pm
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Re: flat field concave imaging gratings?

Post by 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
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Hamish Barker
Posts: 226
Joined: Thu Jun 20, 2019 12:11 am

Re: flat field concave imaging gratings?

Post by Hamish Barker »

Thanks robin. I forgot about the sx.
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