View Full Version here: : Testing of PST and SM60 etalons
02-03-2011, 11:00 PM
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.
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....
03-03-2011, 06:17 AM
Interesting Ken... but what does it all mean?:P;)
I'm guessing the spectra are uncalibrated, hence the x axis scale?
And would the etalons be the first 2 and the blocking filters the others? I had no idea an etalon produced that type of resonance pattern...
03-03-2011, 06:33 AM
The first two are in pixel at 0.2A/pixel and show the resonance pattern of the etalons; each peak shows the bandwidth and the spacing the "finesse"
Yes, the last two are the blocking filter (with the superimposed Ha line)
I'll repeat the testing with a fixed etalon and calibrate it in A -
The main issue is the 10A finesse which would need a 5-7A blocking filter....(you can see how little light the blocking filter passes...so there's never a safety problems upstream of this filter ie your eye!)
08-03-2011, 12:47 AM
That's interesting Ken.
Looking forward to seeing the Lunt blocking filter results.
08-03-2011, 01:33 AM
Unfortunately I only have Coronado blocking filters to test:(
If someone wants to send me a Lunt etalon and or blocking filter I'd be more than happy to test them!
09-03-2011, 02:46 PM
So basically the tests were to see if the filters on these scopes were within spec? I envy you, you have all the snazzy top notch gear!:cool:
Have you obtained any spectra scans using basic scope and Ba'ader solar filter to record the sun's spectra yet?
I ask because if the spectra of our sun can be matched/wave fitted to another solar system's sun out there, could be a good place for further study for conditions to support life on it's surrounding planets. What do you think, would that work?
10-03-2011, 05:51 PM
Has anyone performed a spectroscopic scan of their daytime sky yet? if so, have you noticed any absorbtion lines in the aluminum spectral band(s)?
10-03-2011, 06:08 PM
The daytime sky spectrum is the solar spectrum with atmospheric absorption lines.
The BASS Solar spectrum details all the obvious absorption lines, their wavelength and intensity
10-03-2011, 06:36 PM
But it won't tell you if someone is spraying aluminum in the air in your area. I'm finding some really disturbing information in regards to this phenomena. Just wondering if you came across any data to confirm it, that's all.
25-04-2011, 07:08 AM
This guy is using a PST etalon, Lunt BF and Baader D-ERF with excellent results.
(use google to translate from french)
and his latest results:
I think they speak for themselves.
25-04-2011, 02:47 PM
Thanks for that.
It certainly looks very good. The combination of the Lunt B1200 and the PST etalon seems to work well together... now I know of at least two successful PST/ Lunt mods....I'll add that to my PST mod write-up.
25-04-2011, 07:57 PM
I thought there was some issue with Lunt BFs not compatible with Coronado etalons?
25-04-2011, 08:01 PM
Certainly was a concern that the finesse and the bandwidth of the PST etalon wouldn't match the Lunt blocking filter bandwidth and position - it would appear that at least some (hopefully all!) the Lunt BF's can be used on the PST mod.
25-04-2011, 11:52 PM
If I were able to borrow a Lunt BF from someone for a day, what equipment and process would I need to calculate a bandwidth and finesse of it?
26-04-2011, 12:07 AM
The blocking filter will only show a transmission bandwidth and a central wavelength ( similar to the last two images in the first post) According to the finesse data for the PST it would have to have a bandwidth of around 5-6A centred on Ha.
Any slit spectroscope with a resolution of R=8000 or so would do the job ( able to resolve down to 0.75A at Ha)
A clear focused image in FIT format can be calibrated in Vspec etc. You get the spectral image I can help.
17-05-2011, 05:33 PM
Just an update. I've found a guy over here who has a Lunt 60 double stack with a BF1200 blocking filter.
I'll borrow the Lunt BF and compare it with the Coronado BF's I have. Should be able to get bandwidth and transmission data.
I'll also try the Lunt on my SM60 setup as well as the 88mm modded PST.
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