A spectrohelioscope is born!!!

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Re: A spectrohelioscope is born!!!

Post by Montana »

Well done! a great achievement :bow: the contrast on the filaments is amazing.

I can't help with the lines though ;)

Alexandra


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Re: A spectrohelioscope is born!!!

Post by marktownley »

Cool stuff!


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Re: A spectrohelioscope is born!!!

Post by Merlin66 »

Which camera are you using?
The processing/ camera combo I think is the issue.
Well done!
Onwards and Upwards!


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Re: A spectrohelioscope is born!!!

Post by swisswalter »

Hi Vincent

a great step forward


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: A spectrohelioscope is born!!!

Post by p_zetner »

Hi Vincent.

You're making great progress with the images! This is encouraging as I will be bringing my own spectrohelioscope into operation this summer ... soon, hopefully!

As far as the horizontal banding on your images goes, you could address the problem with image processing. The image processing package ImageJ has a Fast Fourier Transform (FFT) bandpass filter which allows very simple reduction / removal of stripes in an image. This would most likely go a long way to eliminating the problem ... but it doesn't address the source of the problem for which I can't make any suggestions at the moment.

Cheers.
Peter.


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Re: A spectrohelioscope is born!!!

Post by JoseACastro »

Wow!!!!!!!! Congratulations on a great looking gear. That's awesome!


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Re: A spectrohelioscope is born!!!

Post by p_zetner »

Hi Vincent.

Just for fun, I downloaded one of your latest images and processed it a little in ImageJ (and some PhotoShop).
Here is the result.


Cheers.
Peter.


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Re: A spectrohelioscope is born!!!

Post by DSobserver »

hey not too bad!

I found that it's a real processing issue coming from the soft. Could be that I found the solution, but my week end issue was the focus. I really need to improve this latest point!

What type of spectro are you going to build?


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Re: A spectrohelioscope is born!!!

Post by p_zetner »

Hi Vincent.

The design is rather typical, similar principle to yours, based on Christian Buil's ideas. In my case, I found a Czerny-Turner spectrograph which I have modified to use, basically as a grating holder! The basic components are:

Telescope: 100mm f/10 (Rubinar mirror-lens) with front mount ERF (UV-IR cut).
Collimator: 300mmfl telephoto (Pentax M42 mount)
Entrance Slit: 25 micron x 25mm long (Jarrel-Ash)
Grating: Edmund Optics 1800 or 2400 lines/mm, 30mm x 30mm.
Camera Lens: 135mmfl (Pentax M42 mount) (longer fl for higher magnification can be used)

I expect a resolution of 0.35 angstroms (2400 l/mm grating) or 0.47 angstroms (1800 l/mm) and a solar image diameter of 4.2mm (on a 1/3" ccd). Slit image on the ccd will be 11.25 microns, so slightly oversampled with 4.54 micron pixels.

Everything is constructed and nearly ready to go. I am waiting for one adapter (!) to assemble and test.
I'll post pictures once I begin testing.

Cheers.
Peter.


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Re: A spectrohelioscope is born!!!

Post by Merlin66 »

Peter,
A great project!
I've run your data through SimSpec V4....
A 30 x 30 grating will be vignetted with both the 1800 and 2400 l/mm.
Your dispersion looks like 0.2A/pixel, (depending on the camera) and resolution of 0.7A.
Look forward to seeing the set-up.

Attached files SimSpecV4_1c_peter.zip (20.4 KB)


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Re: A spectrohelioscope is born!!!

Post by highfnum »

great work


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Re: A spectrohelioscope is born!!!

Post by p_zetner »

Hi Ken.

Thanks for your comments and the spreadsheet!

You're right about the vignetting, but it is fairly minimal and will affect light throughput more than spectral resolution (for a 25 micron slit). With the 1000mmfl (f/10) telescope and the 300mmfl collimator, an exit pupil diameter of 33.3mm will be imaged on to the 30x30mm grating - not too much of a loss.

I've just begun to look through the spreadsheet and notice that the incident angle (57.2 deg) used there is rather large. My configuration is somewhat different than Buil's and will allow smaller incident / diffraction angles (and, consequently, an anamorphic factor closer to 1). Also, the camera in the spreadsheet has 6.45 micron pixels as opposed to the DMK camera's 4.54 micron pixels. These factors might account for the discrepancies between some of our numbers.

Cheers.
Peter.


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Re: A spectrohelioscope is born!!!

Post by Merlin66 »

Peter,
Re the vignetting...the height of the grating is close, but the width requirement (cell G24) is the one to watch. Obviously light loss is not a major factor for solar!
The total angle (G18) comes down to the spacing of the collimator/ imaging lens and when larger lenses are involved either increased distances to the grating or increased angles. Only a Littrow configuration (Like Fulvio Mete's layout) will give a balanced anamorphic factor.
The drop down list of cameras has the DMK listed - increases sampling but not resolution..
Onwards and Upwards


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Re: A spectrohelioscope is born!!!

Post by p_zetner »

Hi Ken.

As I mentioned in an earlier post, my spectrometer is built around a Czerny-Turner spectroscope, so maybe I shouldn't have mentioned Christian Buil. I've attached a schematic of the basic C-T portion. There are 3 (plane) fold mirrors to illuminate the grating and redirect the diffracted light. I don't have the same issue with physical interference of the collimator and imaging lenses that Buil's design has - not as severe, anyway.

Cheers.


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Re: A spectrohelioscope is born!!!

Post by Merlin66 »

Peter,
I think I now understand....
I assume M1,M2 and M3 are plane, front surface mirrors.
The 300mm collimating lens feeds M1
The dispersed beam from the grating reflects of M2 and M3 to the 135mm imaging lens.
Certainly the total angle is reduced - say, 10 degrees...
With the indicated spacing (200mm approx from grating to M2) M2 needs to be around 45mm and M3 about 55mm


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Re: A spectrohelioscope is born!!!

Post by thesmiths »

To Peter: normally you would not need a front mounted ERF for a spectrograph as the slit would attenuate the energy. For example, with a focal length of 700mm (assuming 100mm diameter and f7), the diameter of the sun on the slit would be 700/107 = 6.54mm. A 20 micron slit would attenuate by a factor of over 300. A huge amount of light is then lost on its way through the spectrometer. The only issue if your choice of a mirror lens, which would necessitate the ERF. A different choice of front optics (a refractor telescope or normal camera lens) might be better.


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Re: A spectrohelioscope is born!!!

Post by p_zetner »

Hello to "thesmiths".

The problem with my configuration is the use of a catadioptric lens (Rubinar) which has a cemented lens group near the output. I'm pretty sure it wouldn't be able to tolerate the excessive solar heat load. If I configure the system for use with a simple refractor, then I would dispense with the erf.

Nice work on your solar spectroscopy, by the way! Do you notice heating of the slit in your system?

Cheers.
Peter.

(I think I should start a new thread pretty soon. I feel like this one has been hijacked form the original poster! I've just assembled my system and will begin testing shortly. I'll post pictures in a new thread.)


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Re: A spectrohelioscope is born!!!

Post by DSobserver »

;) from my side I never detect a high temperature on the slit...


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Re: A spectrohelioscope is born!!!

Post by thesmiths »

To Peter (you've definitely hijacked this post!): no heating of the slit noticeable. The Thorlabs slit I have is for use with high power lasers and is rated at 1 KW per square mm. As it turns out, the power density of the sun's image does not increase with focal length, only with F ratio. At a constant F ratio, an increase of the lens diameter (how much energy is collected) is balanced by the magnification of the sun's image (how much the energy is spread out). If E is the sun's energy in W per square meter, the energy at the slit is proportional to E divided by F squared. If E is measured in W per square meter, and the intensity at the slit is measured in mW per square mm, the proportionality constant is 11.53 (so if E is 1000W per square meter and the lens if F4, the intensity at the slit is 11.53x1000/16 = 720mW per square mm). This is quite small compared to what the slits are rated for. But of course the 1000W per square meter is only 1 mW per square mm so it is 720 times more intense than natural sunlight.


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Re: A spectrohelioscope is born!!!

Post by DSobserver »

After a terrible winter, I finally could try my SHS V2

Indeed, previous one was mechanically a disaster and focus diificult to manage. Now it's much better but still not perfect....

Previous soft was not stable too, and thanks to wahh, it's now 100% solve. Thanks!!!!! :bow

so here a Cak picture

Image


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Re: A spectrohelioscope is born!!!

Post by marktownley »

That's an excellent image!


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Re: A spectrohelioscope is born!!!

Post by swisswalter »

Hi Vincent

that is a good result after the winter break


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: A spectrohelioscope is born!!!

Post by Montana »

:band2 :band :band2 well done! that is a fabulous picture :bow

Alexandra


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Re: A spectrohelioscope is born!!!

Post by alex »

That is great! I can even see the prominence!


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Re: A spectrohelioscope is born!!!

Post by DSobserver »

thanks :bow


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Re: A spectrohelioscope is born!!!

Post by Wah »

DSobserver wrote:After a terrible winter, I finally could try my SHS V2

Indeed, previous one was mechanically a disaster and focus diificult to manage. Now it's much better but still not perfect....

Previous soft was not stable too, and thanks to wahh, it's now 100% solve. Thanks!!!!! :bow

so here a Cak picture

Image

Nice image and glad to see your problem has been solved :band2


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Re: A spectrohelioscope is born!!!

Post by DSobserver »

Cak picture from today

Image


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Re: A spectrohelioscope is born!!!

Post by swisswalter »

Hi Vincent

oh, sorry I'm not verry happy for you. The other great cracks with spectrogear have to chim in here


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: A spectrohelioscope is born!!!

Post by DSobserver »

Thanks to thesmiths advices for focus and wahh software results is improving

Image
Image

and cak (focus is bad but I know how to manage it, more or less....) :

Image


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Re: A spectrohelioscope is born!!!

Post by marktownley »

Getting there! Good results :)


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Re: A spectrohelioscope is born!!!

Post by swisswalter »

Hi Vincent

improvements, step by step. Very interesting thread


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: A spectrohelioscope is born!!!

Post by DSobserver »

I just realize that last version of wahh soft manage smile issues!

So here are an other treatment version from same acquisition as yesterday including now a soft FFT treatment


Image
Image


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Re: A spectrohelioscope is born!!!

Post by swisswalter »

Hi Vincent


great, step by step improvements


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: A spectrohelioscope is born!!!

Post by fulvio.mete »

Hi, Vincent:
the way to the spectrohelioscopy is an hard one, but your improvements are noticeable, well done.


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