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PostPosted: Mon Apr 23, 2007 1:37 pm 
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Thanks wolf, your description is exactly what I mean.

I don't have an OPL to demonstrate step one of what I was suggesting anyone try. But, silly me, I can do the same thing with my prism 'scope. Here's some pictures (click on the pix to bring up a larger version)...

The experimental set-up. A bright lamp sticking out of a block of wood on the left, a hand spectroscope in the middle, and an index card on the right. Forget about the cardboard to block light, the 'scope itself blocks light well enough to see the rainbow.
Image

I plugged in my bright lamp, turned out the overhead lights, closed the blinds, and moved the index card toward the rear of the spectroscope. And voila, close to the 'scope, a rainbow projected onto the card.
Image

A little closer view of the rainbow.
Image

I set this up in about five minutes just to quickly locate the focal point of the spectroscope. I used an incandescent lamp lying around to provide a continuous spectrum. You can locate the focal point much more sharply by putting a gem between light source and 'scope to see sharp absorption lines, or by using a fluorescent light to show sharp, bright emission lines. I have no gems :cry: , so I use the latter method.


Last edited by Brian on Mon Apr 23, 2007 1:45 pm, edited 1 time in total.

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PostPosted: Mon Apr 23, 2007 1:44 pm 
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Okay, Brian, I'm semi-impressed :) .

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 Post subject: oops my goof
PostPosted: Sun May 06, 2007 5:10 pm 
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Reading this thread and recovering from a bout with the flu, I realize that I must have left off an important if not vital component to my toy. I know that using the OPL requires a lens to see the spectra on my retina, so it seems logical that if you remove the fixed lens from the JamCam and place the OPL in its place that you will need some kind of focusing lens to make it focus onto the ccd of the JamCam. duuuuh sorry about that, I thought that all OPL's were alike, but after careful examination of my unit, I can focus the spectra on a frosted piece of glass or plastic and read the spectra, yet my new OPL will not do this. why I do not know...
Any way I am trying to get my photos on some kind of web site to upload them to you guys so that you can critique what I have found..
Winstone


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PostPosted: Wed May 23, 2007 2:53 am 
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My friend Ioannis has been cogitating again , on the spectra of light sources.
If you want to know why things look different in different colors of light take a look Here


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PostPosted: Wed May 23, 2007 11:28 am 
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Oh my! That is some fascinating work :shock: . Shall bookmark that site.

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PostPosted: Wed May 23, 2007 12:08 pm 
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Gene put up the link for a lot of color theory, and resulting theoretical spectra of light sources.

I first ran across this guy's work on the web as I was searching for emission spectra of different light sources. He's made a lot of interesting measurements using a spectroscope... much like the type discussed in this thread.

So I think it is worth posting the link to his spectral measurements of real lamps.


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PostPosted: Sun Jun 24, 2007 9:20 pm 
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Maybe I am missing something obvious here (It HAS been known to happen!) but why are people taking apart cameras in order to use a two dimensional MOS array, when the linear array, a modern version of the old reticon camera, would be sufficient to detect and record spectral lines?
You can take one of these and the associated electronics out of an old scanner.

Whether you use a grating or a prism train, it should work, and you might even be able to get down to the near IR. And scanners are SO cheap now, they are everywhere, including dumpsters. Their output can even be USB, but it will take an Alpha Geek programmer to modify the drivers or write them.

Why drive and read a (for example) 640X480 matrix when you can address individual lines?

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 Post subject: Simple webcam setup...
PostPosted: Tue Jul 31, 2007 2:37 pm 
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Hi,
My first post, but after buying the OPL pocket scope Ive been rather hooked on spectral analysis. I do use a gretag eye-one spectrophotometer for printing and monitor calibration purpose its handy to use as a reference, anyhow using a cheap Logitec webcam and the grating scope plus "v-spec" or visual spec astronomy software (freeware) its possible to make quite detailed spectrographs once you have calibrated to a known source e.g florescent tube or sodium d line.

Heres a screen shot showing the v-spec software and "bable colour" which is used with the real spectroscope, as you can see the OPL scope + v-spec is resolving more detail. A Digital SLR is able to resolve much more, and a modified point and shoot 8mp camera like the Samsung digimax S800 with its IR hot mirror removed in mono mode + the OPL pocket scope make quite a sensitive instrument, although lacking in dynamic range compared to e.g 20D DSLR. Either way Im still surprised how detailed the OPL pocket scope really is when used with the naked eye, fantastic device for its price.

http://urlme.net/opl/oplscope-vspec.jpg

The optical setup is rather simple, the outer lens holder of the webcam was removed so it could focus closer and a holder was made for the OPL scope turning down some plastic on a lathe. The holder or adapter also fits into 52mm camera lens step rings, so its possible to mount it directly in front of e.g Canon EF 50mm lens and get quite a decent spectral spread over the sensor.

Im in the process of making an 85mm adapter which should give slightly more than full frame coverage on the 20D. Coupled with v-spec it should prove quite a powerfull method of analysis.

Oh I should point out Im waiting for some gems from OPL :-)

I would also like to mention that Colin Winter's advice has been nothing short of excellent, most helpful in email with my odd question to too..

Kind regards all,
Mike.


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PostPosted: Wed Aug 01, 2007 1:07 am 
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Welcome aboard Mike!
Spectroscopy does get under your skin. :D
That Babelcolor software. Can it take spectra input as , say .xls spectral files.
I looked at their website and it seemed to say that it could only eat data from an X Rite Eye One or Eye One Pro. If that is the case maybe the reason that
the spectrum doesnt look as good as the one that you took with the OPL is that there arent very many pixels in the spectrum.
The EyeOne divides the visible spectrum into 32 10 nanometer wide channels
A web cam probably does at least three times better than that even if its a color camera.

What other kinds of spectroscopy are you doing? Astro?
Gene


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PostPosted: Wed Aug 01, 2007 4:21 pm 
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I thought the paper linked below would be helpful for those who are scratching their head as they read this thread.

It basically deals what we see using a handheld spectroscope comparatively with the spectrophotometer, why the human eye is a very limiting factor, comparative charts and spectra as well as the sensitivity of the digital camera in detecting absorption spectra.

It answered some of my questions anyway, but probably pretty basic stuff for our spectroscopy experts.

http://www.australiangemmologist.com.au/gem_spectra.pdf


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PostPosted: Sun Aug 05, 2007 3:25 pm 
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G4Lab wrote:
Welcome aboard Mike!
Spectroscopy does get under your skin. :D
That Babelcolor software. Can it take spectra input as , say .xls spectral files.
I looked at their website and it seemed to say that it could only eat data from an X Rite Eye One or Eye One Pro. If that is the case maybe the reason that
the spectrum doesnt look as good as the one that you took with the OPL is that there arent very many pixels in the spectrum.
The EyeOne divides the visible spectrum into 32 10 nanometer wide channels
A web cam probably does at least three times better than that even if its a color camera.

What other kinds of spectroscopy are you doing? Astro?
Gene


Hi,
Bablecolour accepts quite a few formats or rather patch tool does, Ive only tried it with its native formats and specificially babelcolor cta in spectrum tools mode. The eye-one is 3.3nm internally reporting at 10nm which explains the course graph. One problem I have not been able to solve yet is the absolute intensity calibration. Its quite straight forward to get the wavelenght scale fairly acurate but the absolute intensity even with a known 99% reflectance target isnt easy due to the capture techniques used. (e.g far better to use a line ccd/pda) spectronic devices in the UK sell a complete line array with usb drivers but Id rather try the home brew approach first :)

I will be doing some astro work just as soon as the larger teaching model along with some sample gems arrives :)

BR;
Mike.


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PostPosted: Fri Nov 21, 2008 11:21 pm 
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There is a very high quality monochrome (ie. black and white) ccd camera up for auction on www.labx.com

It is made by dage-mti of Michigan City Indiana. Intended for use with microscopes. Very sensitive and accurate. Originally cost a small fortune.

Look here.

This would be the perfect camera to use for a Hanneman video spectroscopy set up.


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