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Main
Date: 27 Aug 2007 22:43:12
From: Macro
Subject: Optical Spectrometer
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I'm wanting to build an optical spectrometer like this one.
http://ii.uwb.edu.pl/astas/spektrometr/index-en.html
Here is a discussion that went on elsewhere.
http://groups.google.com/group/sci.astro/browse_thread/thread/c59376ae3ec265c5/#
Tell me all you can!
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Date: 30 Aug 2007 16:24:20
From: canopus56
Subject: Re: Optical Spectrometer
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On Aug 30, 4:21 pm, Macro <marcus.je...@gmail.com > wrote:
> I have some doubts on these programs on that website I listed. I used
> it and both of the computers I accesed it on crashed. How can I remove
> the programs from my flash drive without killing another computer?
P.S. - If you are concerned about the above programs, look at Vspec
that was recommended to you upthread - at url:
http://astrosurf.com/vdesnoux/
- C
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Date: 30 Aug 2007 16:18:57
From: canopus56
Subject: Re: Optical Spectrometer
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On Aug 30, 4:21 pm, Macro <marcus.je...@gmail.com > wrote:
> I have some doubts on these programs on that website I listed. I used
> it and both of the computers I accesed it on crashed. How can I remove
> the programs from my flash drive without killing another computer?
The files all appear to be self-contained exe applications. Just
delete them. They appear to run fine on my Win XP SR2 box. - C
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Date: 30 Aug 2007 22:21:23
From: Macro
Subject: Re: Optical Spectrometer
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I have some doubts on these programs on that website I listed. I used
it and both of the computers I accesed it on crashed. How can I remove
the programs from my flash drive without killing another computer?
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Date: 30 Aug 2007 12:29:08
From: canopus56
Subject: Re: Optical Spectrometer
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On Aug 30, 12:50 pm, canopus56 <canopu...@yahoo.com > wrote:
> On Aug 27, 4:43 pm, Macro <marcus.je...@gmail.com> wrote:
> > I'm wanting to build an optical spectrometer like this one.http://ii.uwb.edu.pl/astas/spektrometr/index-en.html . . . .
> > Tell me all you can!
P.S. - Here are a couple of amateur websites that show what can be
done with a simple low-resolution diffraction grating:
http://www.regulusastro.com/regulus/spectra/index.html
http://www.astroman.fsnet.co.uk/genspec.htm
- Canopus56
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Date: 30 Aug 2007 11:50:09
From: canopus56
Subject: Re: Optical Spectrometer
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On Aug 27, 4:43 pm, Macro <marcus.je...@gmail.com > wrote:
> I'm wanting to build an optical spectrometer like this one.http://ii.uwb.edu.pl/astas/spektrometr/index-en.html . . . .
> Tell me all you can!
There are few options with increasing resolution resulting in
increasing expense.
A simple commercial diffraction grating for low dispersion
spectrographs is the Rainbow Optics spectroscope.
http://www.starspectroscope.com/
For a low dispersion design and a high dispersion design (with basic
background physics), see:
Stephen F. Tonkin (ed.) 2002. Practical Amateur Spectroscopy.
Springer. ISBN 1-85233-489-4
http://www.amazon.com/Practical-Amateur-Spectroscopy-Stephen-Tonkin/dp/1852334894/ref=pd_bbs_sr_1/104-0569803-8297508?ie=UTF8&s=books&qid=1188498495&sr=8-1
Another low dispersion design based on "bolt-together" parts is Rick
Evans' spectroscope for lunar work found in issue #7 of the
Selenography Today:
http://digidownload.libero.it/glrgroup/selenologytoday7.pdf
- Canopus56
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Date: 29 Aug 2007 01:26:48
From: warner
Subject: Re: Optical Spectrometer
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Macro wrote:
> On Aug 27, 10:22 pm, Warner <notB...@mchsi.com> wrote:
> > Macro wrote:
> > > I'm wanting to build an optical spectrometer like this one.
> > >http://ii.uwb.edu.pl/astas/spektrometr/index-en.html
> >
> > > Here is a discussion that went on elsewhere.
> > >http://groups.google.com/group/sci.astro/browse_thread/thread/c59376a...
> > > Tell me all you can!
> >
> > Robin may chime in here but this would be an utter waste of time
> > to build. Much better to simply get a transmission grating
> > and download free Vspec. Consult Google for gratings, vpsepc,
> > and anything else you need. If you cannot afford a grating, eg
> > Hawksley Star Analyser, Badura Starspectroscopre, or Baader
> > Blazegitter,then goto Welch Scientific and get a cheap holo
> > grating and off you go to your destiny.
> >
> > Any other questions, ask away -
> > Jerry
>
> Well I wasn't sure what the advantages and disadvantages were. I knew
> I could design it so that I could change it into a camera . Also I've
> just started my preliminary studies so can you tell me the advantages
> in a transmission grating. I actually was going to incorporate a
> transmission grating into the spectroscope.
The TR grating is your best option in one of three positions:
either as an objective grating in front of the scope or camera for wide field
spectra or (2) placed in a 1.25" filter holder and screwed to an eyepiece
(desirable for visual work), or in a round or rectangular filter holder
attached to the 1.25" nosepiece
on your webcam without lens and IR filter.
If you cannot afford one of the name-brand gratings then let me suggest the
good cheap holo grating available in America from Welch Scientific #CP-30176-00
which comes in a 6x6"
sheet and 530 lins per mm, but importantly blazed for "1st order
efficiency". In Europe a comparable grating is the Jeulin grating of France
available from Paton Hawksley in the UK at approx.
E20. Many people in EU have started with the Jeulin grating.
It is a very fine grating of approx 200 lpm but blazed for 1st order
(approx 70% efficiency). It is very important your grating be blazed
for first order efficiency in order that the spectrum be close to the
zero order image (so you can find and see it easily) but also so
the full spectrum will fall within the confines of the webcam or ccd chip.
Gratings far exceed ordinary prisms in dispersion, brightness,
an clarity of spectrum. That is my main objection to your use of
a prism plus the difficulty of mounting and handling the prism in
the optical train from telescope to camera. However, a prism
can be used as an 'objective prism' in front of small aperture scopes
and 35mm cameras.
Two other big pieces of advice: (1) do a Google search for "amateur
spectroscopy" and you will find much good material to study and learn from,
both pracitcal and theoretical. (2) Subscribe to the Yahoo "Star Analyser"
Group and the "Amateur
Spectroscopy" group. and read all back material and follow
people's posts. You will gain a wealth of experience from these
sources as the field of amateur spectroscopy runs a very wide
range from newbies to experienced professionals and all willing
to help and learn from each other. A nicer group of people you
will seldom find.
I should mention Mr. Robin Leadbetter of the UK who is a leader
in amateur spectroscopy. We all have benefitted from Robin's experince and
wisdom. Google up Rob's website and follow it.
Robin is very experienced in webcam spectroscopy.
Get some lamps to bench test your projects with. Cheap neon,
tungston continuous, UV Hg black lite bulb. These lights not only help in
calibration but help you optically align and perfect your
optical setups using bright line emission spectra (neon, Hg, etc).
I use a-Lyra (Vega) for standard stellar testing due to its bright Hb-Hd lines
easily visible in any good spectroscope. If your
spectroscope will not resolve Hbeta 4861 and Hgamma 4340
then you know there is something lacking in your spectroscope setup. For solar
testing my equipment I use a 1mm pinhole in a
full aperture mask made of black poster board. I focus the scope
looking for absorption line resolution in the "green" (E-line 5270
and b-lines ~5183 Mg triplet). These tests confirm the spectroscope is working,
as a practical assessment.
I hope some of this helps -
Jerry
--------------79F51B3BEFE01AEDAAAE2C58
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<!doctype html public "-//w3c//dtd html 4.0 transitional//en" >
<html >
<p >Macro wrote:
<blockquote TYPE=CITE >On Aug 27, 10:22 pm, Warner <notB...@mchsi.com>
wrote:
<br >> Macro wrote:
<br >> > I'm wanting to build an optical spectrometer like this one.
<br >> ><a href="http://ii.uwb.edu.pl/astas/spektrometr/index-en.html">http://ii.uwb.edu.pl/astas/spektrometr/index-en.html</a>
<br >>
<br >> > Here is a discussion that went on elsewhere.
<br >> ><a href="http://groups.google.com/group/sci.astro/browse_thread/thread/c59376a">http://groups.google.com/group/sci.astro/browse_thread/thread/c59376a</a>...
<br >> > Tell me all you can!
<br >>
<br >> Robin may chime in here but this would be an utter waste of time
<br >> to build. Much better to simply get a transmission grating
<br >> and download free Vspec. Consult Google for gratings, vpsepc,
<br >> and anything else you need. If you cannot afford a grating, eg
<br >> Hawksley Star Analyser, Badura Starspectroscopre, or Baader
<br >> Blazegitter,then goto Welch Scientific and get a cheap holo
<br >> grating and off you go to your destiny.
<br >>
<br >> Any other questions, ask away -
<br >> Jerry
<p >Well I wasn't sure what the advantages and disadvantages were. I knew
<br >I could design it so that I could change it into a camera . Also I've
<br >just started my preliminary studies so can you tell me the advantages
<br >in a transmission grating. I actually was going to incorporate a
<br >transmission grating into the spectroscope.</blockquote>
The TR grating is your best option in one of three positions:
<br >either as an objective grating in front of the scope or camera for
wide field spectra or (2) placed in a 1.25" filter holder and screwed to
an eyepiece (desirable for visual work), or in a round or rectangular filter
holder attached to the 1.25" nosepiece
<br >on your webcam without lens and IR filter.
<p >If you cannot afford one of the name-brand gratings then let me suggest
the good cheap holo grating available in America from Welch Scientific
#CP-30176-00 which comes in a 6x6"
<br >sheet and 530 lins per mm, but importantly blazed for "1st order
<br >efficiency". In Europe a comparable grating is the Jeulin grating of
France available from Paton Hawksley in the UK at approx.
<br >E20. Many people in EU have started with the Jeulin grating.
<br >It is a very fine grating of approx 200 lpm but blazed for 1st order
<br >(approx 70% efficiency). <u>It is very important your grating be blazed</u>
<br >for first order efficiency in order that the spectrum be close to the
<br >zero order image (so you can find and see it easily) but also so
<br >the full spectrum will fall within the confines of the webcam
or ccd chip.
<p >Gratings far exceed ordinary prisms in dispersion, brightness,
<br >an clarity of spectrum. That is my main objection to your use of
<br >a prism plus the difficulty of mounting and handling the prism in
<br >the optical train from telescope to camera. However, a prism
<br >can be used as an 'objective prism' in front of small aperture scopes
<br >and 35mm cameras.
<p >Two other big pieces of advice: (1) do a Google search for "amateur
spectroscopy" and you will find much good material to study and learn from,
both pracitcal and theoretical. (2) Subscribe to the Yahoo "Star Analyser"
Group and the "Amateur
<br >Spectroscopy" group. and read all back material and follow
<br >people's posts. You will gain a wealth of experience from these
<br >sources as the field of amateur spectroscopy runs a very wide
<br >range from newbies to experienced professionals and all willing
<br >to help and learn from each other. A nicer group of people you
<br >will seldom find.
<p >I should mention Mr. Robin Leadbetter of the UK who is a leader
<br >in amateur spectroscopy. We all have benefitted from Robin's experince
and wisdom. Google up Rob's website and follow it.
<br >Robin is very experienced in webcam spectroscopy.
<p >Get some lamps to bench test your projects with. Cheap neon,
<br >tungston continuous, UV Hg black lite bulb. These lights not only help
in calibration but help you optically align and perfect your
<br >optical setups using bright line emission spectra (neon, Hg, etc).
<p >I use a-Lyra (Vega) for standard stellar testing due to its bright
Hb-Hd lines easily visible in any good spectroscope. If your
<br >spectroscope will not resolve Hbeta 4861 and Hgamma 4340
<br >then you know there is something lacking in your spectroscope setup.
For solar testing my equipment I use a 1mm pinhole in a
<br >full aperture mask made of black poster board. I focus the scope
<br >looking for absorption line resolution in the "green" (E-line 5270
<br >and b-lines ~5183 Mg triplet). These tests confirm the spectroscope
is working, as a practical assessment.
<p >I hope some of this helps -
<p >Jerry
<br >
<br >
<br >
<br >
<br > </html>
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Date: 29 Aug 2007 18:29:09
From: I.N. Galidakis
Subject: Re: Optical Spectrometer
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warner wrote:
[snip]
> Gratings far exceed ordinary prisms in dispersion,
yes.
> brightness,
no.
> an clarity of spectrum.
no.
Prisms are always supperior to gratings in terms of brightness, because all the
energy is concentrated in one spectrum while in gratings the energy is
distributed in all the different order spectra and while the two first order
spectra are the brightest (which is already bad enough because most of the
energy splits in two), there is still energy missing which has gone to the
higher order spectra, even when the grating is blazed.
> That is my main objection to your use of
> a prism plus the difficulty of mounting and handling the prism in
> the optical train from telescope to camera.
[snip]
Spectroscopic prisms are not limited to equilateral prisms which have mounting
difficulties. There are double amici prisms which mount directly between
objective and eyepiece and cause no significant deviation from the optical axis.
However, I agree that mounting a grating in the optical train is obviously
easier than mounting any type of prism, equilateral or not.
> I hope some of this helps -
>
> Jerry
--
I.N. Galidakis
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Date: 30 Aug 2007 01:22:47
From: Terry
Subject: Re: Optical Spectrometer
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"I.N. Galidakis" wrote:
> warner wrote:
> [snip]
>
> > Gratings far exceed ordinary prisms in dispersion,
>
> yes.
>
> > brightness,
>
> no.
>
> > an clarity of spectrum.
>
> no.
>
> Prisms are always supperior to gratings in terms of brightness, because all the
> energy is concentrated in one spectrum while in gratings the energy is
> distributed in all the different order spectra and while the two first order
> spectra are the brightest (which is already bad enough because most of the
> energy splits in two), there is still energy missing which has gone to the
> higher order spectra, even when the grating is blazed.
>
As a general theoretical statement yes, but as a practical matter
in diverse applications, there are many variables which detract
from prisms as an ideal principle. Given the ease of working with gratings vs prisms
if your grating is blazed for a high effiency in
some order single side, then there would be no advantage to a
prism - and several disadvantages. In additon the dispersion available in gratings
usually exceeds that of ordinary prisms.
Gratings have come so far technologically the use of prisms today
is usually reserved for special applications. But, there is nothing
at all wrong with using a prism in a dispersive capacity if that is
one's choice. Just to be aware of the differences between prisms
and gratings and the best uses of each.
I applaud the posters efforts and wish him well -
Jerry
>
> > That is my main objection to your use of
> > a prism plus the difficulty of mounting and handling the prism in
> > the optical train from telescope to camera.
> [snip]
>
> Spectroscopic prisms are not limited to equilateral prisms which have mounting
> difficulties. There are double amici prisms which mount directly between
> objective and eyepiece and cause no significant deviation from the optical axis.
>
> However, I agree that mounting a grating in the optical train is obviously
> easier than mounting any type of prism, equilateral or not.
>
> > I hope some of this helps -
> >
> > Jerry
> --
> I.N. Galidakis
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Date: 28 Aug 2007 20:41:37
From: Macro
Subject: Re: Optical Spectrometer
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On Aug 27, 10:22 pm, Warner <notB...@mchsi.com > wrote:
> Macro wrote:
> > I'm wanting to build an optical spectrometer like this one.
> >http://ii.uwb.edu.pl/astas/spektrometr/index-en.html
>
> > Here is a discussion that went on elsewhere.
> >http://groups.google.com/group/sci.astro/browse_thread/thread/c59376a...
> > Tell me all you can!
>
> Robin may chime in here but this would be an utter waste of time
> to build. Much better to simply get a transmission grating
> and download free Vspec. Consult Google for gratings, vpsepc,
> and anything else you need. If you cannot afford a grating, eg
> Hawksley Star Analyser, Badura Starspectroscopre, or Baader
> Blazegitter,then goto Welch Scientific and get a cheap holo
> grating and off you go to your destiny.
>
> Any other questions, ask away -
> Jerry
Well I wasn't sure what the advantages and disadvantages were. I knew
I could design it so that I could change it into a camera . Also I've
just started my preliminary studies so can you tell me the advantages
in a transmission grating. I actually was going to incorporate a
transmission grating into the spectroscope.
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Date: 27 Aug 2007 23:22:42
From: Warner
Subject: Re: Optical Spectrometer
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Macro wrote:
> I'm wanting to build an optical spectrometer like this one.
> http://ii.uwb.edu.pl/astas/spektrometr/index-en.html
>
> Here is a discussion that went on elsewhere.
> http://groups.google.com/group/sci.astro/browse_thread/thread/c59376ae3ec265c5/#
> Tell me all you can!
Robin may chime in here but this would be an utter waste of time
to build. Much better to simply get a transmission grating
and download free Vspec. Consult Google for gratings, vpsepc,
and anything else you need. If you cannot afford a grating, eg
Hawksley Star Analyser, Badura Starspectroscopre, or Baader
Blazegitter,then goto Welch Scientific and get a cheap holo
grating and off you go to your destiny.
Any other questions, ask away -
Jerry
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Date: 27 Aug 2007 19:28:45
From: LarryG
Subject: Re: Optical Spectrometer
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On Aug 27, 5:43 pm, Macro <marcus.je...@gmail.com > wrote:
> I'm wanting to build an optical spectrometer like this one.http://ii.uwb.edu.pl/astas/spektrometr/index-en.html
>
> Here is a discussion that went on elsewhere.http://groups.google.com/group/sci.astro/browse_thread/thread/c59376a...
> Tell me all you can!
Both the slit and the display screen must be at the foci of the lens.
The points at which various wavelengths arrive at the target screen
will have a non-linear relationship for the prism, and a (more) linear
relationship if you use a diffraction grating.
To calculate the spread of wavelengths on the target screen, you
must know the type of glass the prism is made of, or the groove
frequency of the grating.
If you are serious about building such a device, start with a good
college level book on physics or optics.
Best of luck,
Larry G.
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