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...
Chris
proms May 15th and 16th with spectro in Littrow mode
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proms May 15th and 16th with spectro in Littrow mode
spectro-coronographe ,Bresser 127/1200 ; Bresser 102/1350 , ASI 178MM
- Carbon60
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Re: proms May 15th and 16th with spectro in Littrow mode
Great results, Chris.
Stu.
Stu.
H-alpha, WL and Ca II K imaging kit for various image scales.
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
Fluxgate Magnetometers (1s and 150s Cadence).
Radio meteor detector.
More images at http://www.flickr.com/photos/solarcarbon60/
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Re: proms May 15th and 16th with spectro in Littrow mode
Interesting images and method Chris!
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
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Re: proms May 15th and 16th with spectro in Littrow mode
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!
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Re: proms May 15th and 16th with spectro in Littrow mode
@ 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.
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