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Author Topic: Etalon/BF performance  (Read 2310 times)

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Offline Merlin66

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Etalon/BF performance
« on: 12:14:09, 02 March, 2011 »
Managed to get the five minutes of sunshine needed to set up the Spectra-L200 (1800 l/mm grating 0.2A/pixel) with a PST etalon, a SM60 etalon and a couple of Coronado blocking filters.
I did n't have the SM60 fixed to a scope, just hand held infront of the spectroscope and my shaking hand caused some spreading of the bandwidth. I'll repeat the experiment with it in position on the ED80.
Summary:
The finesse of the PST and the SM60 is very similar (10A) and the blocking filter has a bandwidth around 5A - so a good match.
I'd love to borrow a couple of Lunt etalons/ BF to compare....
Simon- with the bright sunlight and the higher resolution spectroscope the BF curve shows very well - you can see the Halpha dip (also in the PST etalon curves)
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline Nomis Elfactem

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Etalon/BF performance
« Reply #1 on: 12:35:11, 02 March, 2011 »
Huuum... very interesting Ken..... would be interesting to see what you get with the BF10 I have !  I think my only soluton is to get a Coronado one ordered from the States but would like to try it with one first so will put out a plea to "borrow" one when the weather improves.

S.

PS: Your book I ordered has been dispatched so looking forward to a good read !

PPS: I think I'll split this topic out of Johns thread and start a new one !
Simon

Scopes: Astro-Tech AT-111EDT Triplet, TS65ED Quad, Orion ST80, Modded PST-90 Solar Scope, PST Cak (on loan)
Cameras: SXVF H694, Atik 16ic, Canon EOS 600d, DMK41, DMK21, QHY 5L-II (mono & colour)
Accessories: SX USB Filter Wheel, SX OAG, Baader LRGB Ha SI OII Filters, SharpSky Focuser
Mount: EQ6 (EQMOD), SW Star Adventurer, plus a lot (and I mean a lot) of other bits and pieces

Offline Merlin66

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Re: Etalon/BF performance
« Reply #2 on: 15:32:40, 02 March, 2011 »
I'll definately set up the SM60 under "control" conditions and re-test. I'll also do some testing of the Double stacked SM60's to see exactly what the resolution is.
Then there's the double stacked PST etalons.....
Oh, and a SM60 plus a PST as a double stack confirguration....I hope it's not cloudy tomorrow!
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline alexthegreek

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Re: Etalon/BF performance
« Reply #3 on: 14:43:14, 27 March, 2011 »
Have a look here at page 50 .There's an SM60 being tested

http://issuu.com/linkahwai/docs/solarobserver1

Offline Merlin66

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Re: Etalon/BF performance
« Reply #4 on: 07:50:13, 14 May, 2011 »
Just a follow up....
I've found a guy over here who uses a Lunt 60 double stack....I'm going to "borrow" his BF1200 and set it on the spectroscope for direct back to back comparison with the Coronado BF.
C11, C9.25 SCT, 4" Genesis, NEQ6pro, modded 1000D,  ATik314L+, DMK41AF04, SM60DS/BF15, and Spectroscopes (many!).
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/
"Astronomical Spectroscopy for Amateurs", "Grating Spectroscopes-How to Use them" -Springer

Offline colinsk

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Re: Etalon/BF performance
« Reply #5 on: 05:49:06, 04 August, 2011 »
I am surprised that the FSR did not fall off on the edges of the design frequency. The coatings on the etalon must be broadband.

Nice work!

 

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