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Old 27-08-2009, 10:53 AM
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Newbie at the spectroscopy club

Finally, after many months fiddling with various ideas and availability of parts here its is.
The design is based on and using some scrapped components and parts I managed to collect over the years in my drawers and boxes.

Basically, it is a variant of WPO design (http://www.astroman.fsnet.co.uk/newspec.htm)

It uses a small flat 45° mirror (1x3mm) coming from what seems to be the moving coil of the sensitive microamp meter (the type that uses reflected light beam as pointer-indicator). I have couple of those devices, the mirrors appear to be of very high quality.
I am focusing the light of the single star to that mirror (the plan is to place it in the focus of my MTO-1000A telephoto lens, but currently I am experimenting with 50mm lens, as visible on photos), from where the light bounces 90° into 50mm lens (Industar 50 from my old Zenit camera). collimated spectrum beam is to be reflected back by blazed grating (Edmund Optics most likely, still not purchased, currently I am using a piece of DVD) back into the lens, passing closely near the small mirror (but not striking it).
The secondary focus is some 15 mm further than small mirror, where I intend to place the camera, Phillips PCVC690K or something else with BW CCD chip.
What you see on the photos is a terrestrial (erecting) eyepiece (10x microscope actually), currently used for viewing the spectra.

Now the real work may begin
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Old 27-08-2009, 11:41 AM
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sheeny (Al)
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Looks like an interesting project!

Al.
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Old 28-08-2009, 05:52 AM
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Bojan,
Looking good!
A DVD is a 1200 lpm equivalent....
Keep up posted on developments.
Optometrics gratings are cheaper than Edmund and just as good.
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Old 28-08-2009, 10:30 AM
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Quote:
Originally Posted by Merlin66 View Post
Bojan,
Looking good!
A DVD is a 1200 lpm equivalent....
Keep up posted on developments.
Optometrics gratings are cheaper than Edmund and just as good.
Ken, thank you for this info.
The prices are indeed much better than Edmund, and there is much more info available on their website about grating performance.
I think I will go for the smallest one for the start (12.7x12.7mm, it is suitable for the lens system I am using), 1200g/mm, 500nm blaze wavelength (http://www.optometrics.com//App_Themes/optometrics/pdfs/gratings/1200g_mm_Ruled_500_nm_Blaze.pdf), this one looks the best in terms of efficiency over the visible & IR spectrum, and it will cover the CCD sensor I plan to use (TC237, I have build the camera based on this chip a long time ago, was inspired by Audine design, but never really used it).
I can mount it inside the housing, just above the mirror, on short cables..
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Old 29-08-2009, 08:09 AM
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Bojan,
As a multipurpose grating you may find the 600lpm a better starting point.
If you want more resolution you can always use it in the 2nd order.
Fulvio Mete's spectro does this very successfully...
http://www.lightfrominfinity.org/gli_strumenti.htm
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Old 01-09-2009, 05:09 AM
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Hi Ken,

Using the second order is a possibility if you have plenty of light but remember that the efficiency of a blazed grating used in the second order will be much lower (perhaps 5 -10x)

Cheers
Robin
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