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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Wed Jun 13, 2012 2:04 pm 
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:smt016 :smt088 :smt088 :smt110 :smt118 :mrgreen:

Very good snag!


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Triggering works pretty ok but not perfectly with SpectraSuite. Had to write my own software for smoother operations.

I don't know why the later software isn't better. You can download OOIBase 16 and 32 and I think 32 will directly acquire from the USB port. They used to let you download it for free but now they have put a password on it. It certainly worked well enough with the D/A card interfaces. If you want to try it send me a PM. I believe it also was written by StellarNet. Spectra Suite was not. Its a shame that you have to write your own software. They have sold zillions of these and should have been able to iron the bugz out of it.

The passwords for SpectraSuite are all the same. I think one of the profs here has v2.0 and I will see whether I can come up with it for you.

Have you used your experience from the earlier units to make adjustments on the OO unit?


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Sun Sep 23, 2012 3:33 am 
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Have you used your experience from the earlier units to make adjustments on the OO unit?


Sorry Gene, I came here to make question for Brian and realized for some reason I totally missed your latest post.
Current models from OO are even easier to adjust, since there is not need to open the bench of the spectro at all.
Grating is adjustable from the bottom once one realizes the "glue" in screws is not actually glue, just a factory seal for seeing if somebody has adjusted it by own.

So, Brian - did the light source arrive? Wannaseewannasee :smt118

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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Mon Sep 24, 2012 4:50 pm 
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mikko wrote:
So, Brian - did the light source arrive? Wannaseewannasee


It just arrived today. The energetiq light source is MINE!!! Muahahaha :mrgreen:

I've been preparing a special place for it with access to nitrogen tank, so that I can purge the lamp housing of that nasty old oxygen. There's still some more prep to be done, so give me about two weeks to post some pics and spectra.


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Tue Oct 16, 2012 2:56 pm 
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I have only been playing with the light source in spare moments during the past two days, but I want to give a brief report. The light source is bright, bright, bright! Crazy brightness. Opens up a whole new world!

Using my UVVIS (200-850 nm) spectrometer

The first time I tried to collect a light spectrum with my UVVIS spectrometer, in order to not saturate the spectrometer, I had to stand off the light's fiber optic about 30 cm from the spectrometer's fiber. Eventually I'll have to figure out a way to move it closer.

It is apparent that spectrometer detection efficiency peaks around 500 and decreases from there as wavelength decreases. So the 200-300 nm range is still going to be difficult to measure. But 300-400 nm range will be no problem.

Using my VIS (400-730 nm) spectrometer

Before, I didn't use the VIS spectrometer much. Its high resolution (~0.2 nm) comes with a 25X reduction in light detection, compared to the UVVIS. So it was just too difficult to collect gem spectra. But now... bang! Collecting spectra with this light source is a piece of cake. This spectrometer is now so much fun to use that I've been focusing my attention on it.

Using my VISNIR (350-1100 nm) spectrometer

I haven't tried this one yet.

Other observations

After turning on the light source, it takes a full 20 minutes to settle into a constant emission. So I can't just switch it off to collect a dark spectrum. And it doesn't have an electronic-controlled gate to cover the source. Right now, I am just disconnecting the fiber from the source to collect a dark spectrum. But I'll have to figure out something more efficient.

My safety glasses apparently work as they should. I hold a pair in the path between source and spectrometer (which is pretty easy to do when you have a 30 cm open space), and the counts in the UV range fall to zero.


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Wed Oct 17, 2012 8:59 am 
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great, Brian!!!! :D

any chance to see some spectra samples??? i'd be VEEEEEEEERRRY curious!!!!!! 8)

ciao
albé

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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Wed Oct 17, 2012 6:53 pm 
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Here are some spectra of a 6 inch long ruby laser rod. :D Usually in ruby we see flourescence peak(s) at 694 nm, but in the laser rod these become absorption lines, as I have described here.

These spectra are the raw data... no data smoothing or averaging.

First a composite of spectra taken with my UV-VIS and VIS-NIR spectrometers.
Attachment:
ruby rod UVVISNIR.jpg
ruby rod UVVISNIR.jpg [ 37.16 KiB | Viewed 2579 times ]

Looking at the 200 nm end, the signal gets rather sketchy below 230 nm. Similarly, the signal gets sketchy above 1000 nm. It seems this is due to the detection efficiency of the spectrometers at those wavelengths, rather than the light source.

Also, there is a lot of jittery movement in the signal over the 700 - 900 nm region. I think most of it is due to a slightly incorrect dark subtraction with the NIR spectrometer. Ah well, it was the first time I used that spectrometer. I'll have to pay closer attention next time.

The spectral range covered by each spectrometer overlaps the "fluorescence" lines and their signals matched perfectly across this overlap, so it was very easy to put the two together to cover the entire range.

Lastly, neither of these spectrometers has the resolution required to separate the two "fluorescence" lines at 694 nm.

Next a spectrum collected with my VIS spectrometer with higher resolution.
Attachment:
ruby rod VIS.jpg
ruby rod VIS.jpg [ 32.63 KiB | Viewed 2603 times ]

If you look very closely at the 400 nm edge, you can see some sketchy data, once again due to nearly zero detection efficiency for the spectrometer at those wavelengths.

We can see the beginning of jitters and wiggles around 700 nm. I'm pretty sure these wiggles are real.

It isn't clear in this picture that the "fluorescence" lines are separated, but in the expanded view shown next we can clearly see the 1.4 nm separation between peaks.
Attachment:
ruby rod VIS closeup.jpg
ruby rod VIS closeup.jpg [ 40.33 KiB | Viewed 2603 times ]


Finally, these spectra were very easy to collect. I'll post spectra of another gemstone next week... maybe something really dark, or maybe something that is busy in either the UV or NIR or both. But that is for next week; this week I have a package to post. :wink:


Last edited by Brian on Thu Oct 18, 2012 5:19 pm, edited 1 time in total.

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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Thu Oct 18, 2012 4:29 pm 
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Brian if you need a shutter actuating solenoid let me know. Or even an electronic shutter assembly with or without controls that can talk to LabView.

I would be interested in comparing the spectra of your wonderful goodie to that of my zirconium arc lamps.
These were (in the very small diameter two watt version) the most intense radiant source available until the advent of the laser. They have a very nice almost black body spectrum with a few lines from the fill gas and a couple of zirconium lines. The HBO 103 lamp is pretty radiant too these days.
I am kind of surprised that it takes a while to settle down. This is one of the disadvantages of xenon arcs and arcs generally. When you look with a real time spectrometer like a fiber optic unit you can really see the wavelength by wavelength jumping around. That is one thing that is likeable about incandescent filament sources. They seem more stable. I have not looked at my zircs through an OO spectrometer yet. Since they are actually incandescent arcs rather than short arcs like Xe or Hg (or D2 or Na discharges) they might be an interesting source.

Always fun to get a new toy. :D

PS Where did you get a ruby laser rod??? I have been trying to find one of those to cut up into faceted gemstones for a long time. All the ones on fleabay are always insanely stratospherically overpriced.


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Thu Oct 18, 2012 5:46 pm 
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Gene, for now I'll just hide the light from the gem with a little square of thick black cardboard.

It may seem like one could use the OO spectrometers to compare the two lamps. But as I have found out, the wide-wavelength-range gratings have wickedly complicated response curves. When I collect an emission spectrum using my higher-resolution VIS spectrometer that only covers 400-700 nm range, the spectrum is basically a flat line... as one expects. But collecting an emission spectrum using either the UVVIS or the VISNIR spectrometer, one does not get a flat line... far from it.

So comparing spectral output from the two lamps would probably require a series of spectrometers covering short-wavelength-ranges, like these used for LIBS. But my spectrometers are still good for the gem spectra, which normalizes out the response curve.

I got the laser rod from Anderson Lasers. I've had it for several years. I spoke with Dick Anderson a while ago, and he told me a Chinese company had purchased most his stock. So I am sure whatever is left is going to be pricey.


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Thu Oct 18, 2012 6:13 pm 
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I had never run across Anderson Lasers until recently. I picked up a LIBS spectrometer (four rather than seven spectrometers) and was looking for a laser power supply for it (Need a New Wave Research Tempest or Polaris)
and somebody referred me to him. He didn't have what I needed. I may try to see if LIBS can be done with a Nitrogen Laser which I have several examples of including one that has a few Newtons.

Rods appear on ebay periodically but they always go higher than I want to pay.


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Mon Oct 22, 2012 8:28 pm 
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By the way, the reason I chose to collect spectra of the ruby laser rod is that it is a 6 inch long rod. That means the light source's fiber is separated from the collection fiber by over 15 cm. And yet, these spectra were recorded using an integration time of only 1 ms.


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Mon Oct 22, 2012 10:22 pm 
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I wanted to look at a stone that had a distinctive absorption line in the NIR in order to see what is going on with my VIS-NIR spectrometer. Then I remembered beryls have quite a distinctive dip somewhere beyond 900 nm. So I set up an aquamarine that I had lying around. This stone is a very nice blue color, but with the dichroscope you can see both blue and green. Anyways, I collected one spectrum using my UV-VIS spec and another spectrum using my VIS-NIR spec. Below, we see the spectra overlaid upon each other.

Attachment:
aqua.jpg
aqua.jpg [ 42.13 KiB | Viewed 2523 times ]


I have to say, the overlay is impressive. It would be quite easy to connect the two data curves at, say, 750 nm to create one continuous curve from 300-1000 nm.

We can see the beryl absorption line in the IR that I mentioned at about 958 nm. And there is another absorption line at 427 nm that is associated with the iron that gives the aquamarine its color. And there is another sharp absorption in the UV at 371 nm that I didn't know existed.

Note that the UV-VIS spectrum starts at 300 nm. This is because I have to use a neutral density filter to collect the bare light spectrum, and that filter has a sharp cutoff just beyond 300 nm. Collecting spectra across the 200-350 nm range is going to require a separate UV filter to isolate that light... which, of course, I have on order.

The VIS-NIR spectral curve doesn't show much jittery noise until around 950 nm, where detector efficiency is dropping fast. So it seems the NIR section of the spectrum looks trustworthy, and the jitteryness seen in that region of the ruby spectrum was just a one-off.


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Mon Oct 22, 2012 11:42 pm 
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Aren't there some xenon lines in that invisible IR neck of the woods?

Cool spectrum.


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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Tue Oct 23, 2012 3:08 am 
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VEEERY COOL, Brian!!!! =D> =D> =D>
Keep collecting!!!!!!!! 8) :D

ciao
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 Post subject: Re: spectrometry state of the art lamp?
PostPosted: Tue Oct 23, 2012 3:19 pm 
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Yep, Gene, there are some Xe emission lines out past 800 nm. But in the aquamarine spectrum, the jitteriness above 900 nm is just statistical noise due to the low signal. If I increase collection time by a factor of 100, it'll go away.

As for the ruby spectrum... maybe some of the Xe structure is bleeding through a slightly incorrect normalization. This incorrect normalization arises from the fact that light traveling the 6" length of the rod will be somewhat more confined within its 3/8" diameter than it will be when the rod is removed. So if the rod wasn't absorbing any light, we'd see a slightly larger signal with the rod in place than with it removed. Fortunately this seems to be a problem only for this unusual geometric circumstance.


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