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Etalon info for beginners

Posted: Sat May 16, 2020 8:48 am
by Solar B
Hi Folks

I have been asked for a link to info on etalons in general ... say air spaced v solid or just

a general understanding of bandwidths and how etalons operate.

If anyone can advise on some info on here then that would be great ๐Ÿ‘

Would be good for me to read as well ๐ŸŒž

Thanks .... Brian

Re: Etalon info for beginners

Posted: Sat May 16, 2020 9:03 am
by pedro
Check out C. Viladrich website

http://www.astrosurf.com/viladrich/

Analysis of mica spaced Ha Fabry-Perot etalons
http://www.astrosurf.com/viladrich/astr ... lar/FP.htm

Re: Etalon info for beginners

Posted: Sat May 16, 2020 9:14 am
by Solar B
Thanks Pedro

I have looked at Christians site before but I don't think it's necessarily for beginners though.

Brian

Re: Etalon info for beginners

Posted: Sat May 16, 2020 9:44 am
by AndiesHandyHandies
Hi

The PST shows a whole Sun view with prominences visible.
For visual on Prominences my M180 PST Stage 2 Mod shows brighter more contrasty images than a Daystar Quark I recently bought.
Issue is a small sweet spot and ghosts off the PST etalon, you have to rotate the etalon in the focusser to move away.
Even with a 180mm aperture I get best images with 25mm eyepiece.

The Quark has a circular polarizer in to remove ghost images but it dims the result. Other manufacturers Lunt? do not put in a filter but users complain about the ghosts and lack of light when they fit polarisers.

For a Quark with 4.2x Barlow in I reduced a 102mm F5 Skywatcher/Celestron OTA to be similar to the DS60 OTA Fno 3.5 and fl 350mm and the view improved because of the extra light going through the etalon. Somewhere between the original Quark and my M180 mod for the proms. Detectability is the square of intensity.

Using a little front etalon as an internal etalon inside a bigger OTA modification gets you brighter bigger images but at a cost in terms of the size of a 'sweet spot' for the PST or bandwidth changes across a solid etalon.

Andrew.

Re: Etalon info for beginners

Posted: Sat May 16, 2020 2:48 pm
by rsfoto
Solar B wrote: โ†‘
Sat May 16, 2020 8:48 am
Hi Folks

I have been asked for a link to info on etalons in general ... say air spaced v solid or just

a general understanding of bandwidths and how etalons operate.

If anyone can advise on some info on here then that would be great ๐Ÿ‘

Would be good for me to read as well ๐ŸŒž

Thanks .... Brian
Hi Brian,

Maybe here https://en.wikipedia.org/wiki/Fabry%E2% ... rferometer

Re: Etalon info for beginners

Posted: Sat May 16, 2020 5:19 pm
by Montana

Re: Etalon info for beginners

Posted: Sat May 16, 2020 6:05 pm
by Solar B
Many Thanks All

But I'm still looking for something that's perhaps a little less highbrow if possible ?

Brian

Re: Etalon info for beginners

Posted: Sat May 16, 2020 7:19 pm
by John

Re: Etalon info for beginners

Posted: Sat May 16, 2020 11:30 pm
by Solar B
Thanks John

I had read Colinskis detailed reports before but had long since forgotten about

them ๐Ÿ‘ด

Brian

Re: Etalon info for beginners

Posted: Sun May 17, 2020 6:43 am
by marktownley
Think I might put this in the reference library when the topic goes quiet, a useful post to start Brian.

Re: Etalon info for beginners

Posted: Mon May 18, 2020 8:47 am
by Merlin66
In my recent book โ€œImaging Sunlightโ€ - Springer thereโ€™re a good chapter on the etalon function and current available solar filters.

Re: Etalon info for beginners

Posted: Mon May 18, 2020 1:28 pm
by Bob Yoesle
You might find this CN thread of interest:

https://www.cloudynights.com/topic/4809 ... on-basics/

Re: Etalon info for beginners

Posted: Tue May 19, 2020 3:21 pm
by Solar B
https://www.hpb.com/products/imaging-th ... 3319248721

Is this the book Ken ?

And thanks Bob ..... great to hear from you to ๐Ÿ‘

Oh and I had long since forgotten about that CN thread also ....... my relatively insignificant thread

has turned into something quite significant to me ๐ŸŒž

Brian