proms May 15th and 16th with spectro in Littrow mode

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ChrisHalpha2017
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proms May 15th and 16th with spectro in Littrow mode

Post by ChrisHalpha2017 »

Hello,

i've been working on a problm that's been nagging me for years! Why my images were a bit "shrunk" ?... I finally found the answer. in 1868 they were using prisms and the way they used it introduced no deformations. Diffraction had not been invented yet. Diffraction gratings used in a "classical config" produced whats called anamorphosis : the image is magnified or shrunk in the direction of the spectrum. Still, there is one way to use a grating without this problem : The Littrow design...

Here are the results...
littrow 1200 tm  3_20220515_155542.998_UT +++++++++.jpg
littrow 1200 tm 3_20220515_155542.998_UT +++++++++.jpg (118.92 KiB) Viewed 148 times
1200 tmm littrow spicules_20220515_155518.753_UT comparaison anamorphose.jpg
1200 tmm littrow spicules_20220515_155518.753_UT comparaison anamorphose.jpg (184.69 KiB) Viewed 148 times
image 1_20220516_121432.332_UT.jpg
image 1_20220516_121432.332_UT.jpg (25.04 KiB) Viewed 148 times
2022-05-16-1437_4-CI-R-Sun_Halpha++++_F1647-1784  restacked  annotée.jpg
2022-05-16-1437_4-CI-R-Sun_Halpha++++_F1647-1784 restacked annotée.jpg (306.63 KiB) Viewed 148 times
1800 trmm  mode littrow ++ grand   best++++++++ annotée.jpg
1800 trmm mode littrow ++ grand best++++++++ annotée.jpg (204.37 KiB) Viewed 148 times
600 tmm Littrow  +++ annotée.jpg
600 tmm Littrow +++ annotée.jpg (173.53 KiB) Viewed 148 times
600 tm littrow  grosse protubérance + best_  mode coro.jpg
600 tm littrow grosse protubérance + best_ mode coro.jpg (279.19 KiB) Viewed 148 times
Chris


spectro-coronographe ,Bresser 127/1200 ; Bresser 102/1350 , ASI 178MM
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Carbon60
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Re: proms May 15th and 16th with spectro in Littrow mode

Post by Carbon60 »

Great results, Chris.

Stu.


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Re: proms May 15th and 16th with spectro in Littrow mode

Post by marktownley »

Interesting images and method Chris!


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Re: proms May 15th and 16th with spectro in Littrow mode

Post by Montana »

Fascinating and great shots!!

:bow :hamster:

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fulvio.mete
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Re: proms May 15th and 16th with spectro in Littrow mode

Post by fulvio.mete »

Yes, Chris, i totally agree.I've been using a modified Littrow configuration in all my solar Hires spectrograph and had no problem at all in spectroheliography!


ChrisHalpha2017
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Re: proms May 15th and 16th with spectro in Littrow mode

Post by ChrisHalpha2017 »

@ Fulvio

thanks very much ; I noticed that anamorphosis was getting stronger and stronger when the number of gr/mm and whrn the incidence angle augment in a classical design. Anamorphosis is good in spectroheliography but not with my technique . That's why i tried the Littrow design.

Mine isnt yet a 100% Littrow but its getting quite close and the shape that the diffracted light beam forms on the grating is almost identical than that of the incident beam wich is a sign that both angles are almost identical.


spectro-coronographe ,Bresser 127/1200 ; Bresser 102/1350 , ASI 178MM
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