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 Post subject: Challenger Spectroscope
PostPosted: Wed Feb 27, 2008 3:20 pm 
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Does anyone out there own a Challenger Spectroscope?

http://www.prettyrock.com/challenger-sp ... torial.htm

I'd be very interested in hearing your impressions. The B&W sensor/monitor should be very sensitive and I am curious about the ability to take readings in the near UV and infrared, and the ability to discern lines that would be difficult with a conventional spectroscope - particularly in the blue region.

Also the precision and accuracy of the digital readout?

Thanks.

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PostPosted: Wed Feb 27, 2008 7:29 pm 
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That looks like nick's spectroscope he was marketing through kassoy..it'll do low end uv and high end ir.. you can find additional id bands in those ranges (he demo'd aqua for me).

The instrument worked.. it was around 4-6k.. can't remember.. I dont' know why he would not use a color ccd for it.. they are cheap enough.. and that would be interesting as well.. turning a knob on the scope advanced the nm scale so you could see where it was.. a line down the middle correlated with the setting your looking at so you could get a good split on pairs...

He was using a blazed 3k/line grating as a i recall, optimized for 579 (sodium d) wavelength. The heat filter on the lamp got the bottom pretty hot.. at least the stone didn't..

That's as much as I can recall..

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PostPosted: Thu Feb 28, 2008 12:00 am 
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He undoubtedly used a Black and White camera to avoid the Bayer mosaic pattern and its associated matrix arithmetic.

If anyone is interested in building their own such instrument, I have some
Newvicon microscope cameras which can do up to one thousand one hundred pixels of horizontal resolution but which are actually analog in nature because the sensor is a Newvicon vidicon tube. Very sensitive (0.0008 foot candles for tungsten light) and no discrete pixels. An analog video output which if you would project the right sized spectrum onto the tube faceplate could be directly read as a spectrum intensity graph. (on an oscilloscope connected to the video output.)

The camera head has a C mount and a separate control box which has wide range controls for all video parameters such as gain, brightness , signal levels, and gamma curve. and invert. Different one inch size tubes can be fitted from different purposes. Even though the usual bandwidth for monochrome stuff is five or six megacycles the bandwidth of this is rated about 10 megacycles (megaHz)

The manufacturer of this goodie (Dage MTI of Michigan City Indiana) used to sell them for about $8000 . Since they have become dated they are now blowing em out at $500. (and phony lowered list price of $2400)I will sell up to three of them to whomever would want one for $250 each plus schipping.

Hereis the manufacturer's pdf on the unit.

Here is a page showing a similar camera and the pdf has a high resolution graph of the Newvicon sensitivity curve.

These would be a great video spectroscopy sensor. These cameras were obtained surplus from an outfit which updated some fluorescein angiography setups. That is where the eye doctor injects you with yellow green dye and flashes a blue flash lamp into your eye or just shines a bright blue or UVA light into your eye. As the injected dye goes through your retinal vessels the dye fluoresces and makes them visible. But it isn't much light to catch and image. And these cameras were sensitive enough and accurate enough to do that trick(very low geometric distortion). You could also image Diamond fluorescence with them. (in monochrome but you could see growth patterns) The cameras are equipped with Newvicon type sensors tubes but I have other types too that have different wavelength curves and could be installed in the same camera.


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PostPosted: Thu Feb 28, 2008 11:49 am 
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Gene,

Do you think you could build me an equivalent to the Challenger?

The Challenger price is $4300 with a quoted 3 week delivery.

At that price one might consider an Ocean optics spectrophotometer set-up I suppose but in my limited experience, the correlation between spectrophotometric results and visual acuity combined with a conventional spectroscope are not always clear.

There is a wide range of observed data for a conventional spectroscope. How great would it be to record every spectral line within about 2nm all in just a couple of minutes.

Eventually I'll spring for a Raman rig but for now I just want to help my aging eyes.

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Former Research Gemologist turned sub builder


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