B&W-tech Spectrometer & 473 module: Setup+Mods+Info

[paul1598419]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Some great information, Steve. One thing I didn't see were units for the mercury and hydrogen spectral lines. Unfortunately, my spectrometer doesn't resolve 523nm to where I can see the two lines. I would love to have one that could, but I'm afraid it is beyond my means.

 

[jnrpop]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Be real careful, 532.1 has a 1.1 nanometer gain bandwidth and a second weak line about .35 nm longer then the primary at the right edge (longer wavelength) of the spectrum. A good spectrum of a free running DPSS shows TWO lumps close together.

Hi steve,
This was the spectral capture of my 532nm dpss laser. Indeed there is two lines, second weaker line is to the right

 

[LSRFAQ]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Some great information, Steve. One thing I didn't see were units for the mercury and hydrogen spectral lines. Unfortunately, my spectrometer doesn't resolve 523nm to where I can see the two lines. I would love to have one that could, but I'm afraid it is beyond my means.

Paul, those Hydrogen and Mercury Lines are in Angstroms...

Shift decimal point one place to the left to convert to nanometers.

I edited the above post to add the units...

Steve

 

[LSRFAQ]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Hi steve,
This was the spectral capture of my 532nm dpss laser. Indeed there is two lines, second weaker line is to the right

Yes, and if you use a cruddy peak finding algorithm that second line really throws off your center frequency on calibration. That little bump of a second line, kept us on Ion lasers in the lab for another two years. When doing the measurements we were doing with 24-48 hour exposures, that little "bump" was enough error to throw the whole experiment out of commission. Sandercock Interferometers are very sensitive. Especially when using a LN2 cooled photodiode for low noise.

Hence a growl when I obtained the C315s on loan. The C315 had the stability, but it had that damn tiny peak of a second line too.. It was too close in for us to filter it off with a prism. Now I know how to do it, back then, life was different.

I ended up locking the argon ion resonator to a Iodine adsorption line, by using a small amount of the beam to pass thru the I2 cell and into a detector. That detector's signal was processed to control heaters on each resonator rod of the Ion laser. A couple of op-amps locked the fine tuned 514.5 nm light to one side of its gain curve, which is about 9 Ghz wide, So the laser used had both a Iodine cell and a tunable Etalon.

BTW, the 488 nm Argon line has a weak sister line tucked about .4 nm away from the main 488 line. I'm told it can be a problem on very large frame lasers if your doing holography and your intra-cavity etalon has the wrong finesse or is miss-tuned. .

I've never seen it separated out, but the books say it can be there, SP used to sell a mirror set to reduce its gain some how. Handwritten thanks and one large chocolate dipped vanilla ice cream cone if you can be the first to and second persons to find said second 488 nm argon ion laser line with a surplus B&W Tek spectrometer, and correctly identify its wavelength. Award valid only if present in Akron Ohio for the first two people who can show me the peak in the proper direction by posting a spectrum scan on this thread. Offer invalid after Aug 1 2018. I'd probably mail a Dairy Queen gift card to the first two, and only the first two anyways. Showing me the reference in a book does not count, it must be a spectrum of an actual lasing Argon Ion Laser. Value of ice cream shop gift card or ice cream cone not to exceed 10$.


Steve

 

[paul1598419]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

:crackup: Thanks, Steve. I know what an Angstrom is. It was the fact that you used units for all lines except those that brought out that question. I had no idea that second line was so small in relation to the main one on the 532nm. Will have to have another look when I get the time.

 

[Cyparagon]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

@Cyparagon, comments like this "laymen don't know what sigfigs are" don't support out community and create positive forward motion

Was I wrong? Was I rude?

Someone asked why all the extra digits were there, and I pointed out most people don't know they're useless. How is that problematic? I answered a question with an honest response. If you think providing an accurate assessment is somehow hindering progress, you need to re-evaluate your priorities and perhaps grow some thicker skin.

A few members here have already expressed they were reluctant to post information due to certain members here "Purely criticizing"

You're telling me some people are afraid to post because they might have something wrong? That they might benefit from verifying their information before posting so that is factually sound? I don't understand. I don't understand how that's a problem. What's the alternative? That people have no fear of being corrected or criticized? That's the community you want?

Science and technology thrives because it is OPEN to criticism. Abhorrence to criticism is fundamentally incompatible with science.

 

[Mosc007]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

You're telling me some people are afraid to post because they might have something wrong? That they might benefit from verifying their information before posting so that is factually sound? I don't understand. I don't understand how that's a problem. What's the alternative? That people have no fear of being corrected or criticized? That's the community you want?

Science and technology thrives because it is OPEN to criticism. Abhorrence to criticism is fundamentally incompatible with science.

I am sure many members have noticed errors in what I post here sometimes. By posting wrong information it then leads to a response with the correct information.

No one should be afraid to post something just because it may be wrong. Thats what learning is about.

 

[Civitus]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Cool. You should be able to excite those with any cheap Chinese HV supply that runs on batteries. I believe you can get one for under $5.00. The higher the frequency the better. You should have no problem getting a good calibration using these lamps.

Dear Paul,
Are you speaking about things like these :

https://www.ebay.com/itm/50kV-High-...m=372235292205&_trksid=p2047675.c100005.m1851

https://www.ebay.com/p/15kv-High-Vo...m=382131734381&_trksid=p2047675.c100005.m1851

https://www.ebay.com/itm/3-7V-DC-Hi...or-Ignition-Coil-Step-up-Module-/112962639760

https://www.ebay.com/p/15kv-High-Vo...Module-DC-5v-15v/17018347618?iid=112953012679

Your help is more than welcome
and thanks again

C

 

[LSRFAQ]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Just remember gas plasma devices such as spectrum tubes have a negative Delta V characteristic, so they will need a ballast resistor anywhere from 4.7 Kilo Ohm to 56K Ohms depending on the lamp. Two to five watt wire wound or metal film resistors are desirable as carbon powder based resistors often degrade when used for current limits if the power supply is not self current limiting or does not have a high enough output impedance to limit the current.

Spectrum tubes have an open circuit, gas dependent, firing voltage anywhere from 1500 volts to 5,000 volts and drop to about 100-300 volts once lit and driven to an appropriate current.

Transformers for driving pen-ray lamps usually have a designed in leakage inductance that limits the lamp current. Professional spectrum lamp Transformers for classroom use have a high enough output impedance using fine wire in the secondary, that they will not need a ballast resistor.


Most cheap spectrum tubes are only processed/outgassed at 2x or 3X their design current during manufacture, which can be anywhere from 6 to 15 mA depending on the manufacturers tastes. . If you overdrive them, they will usually outgas from the tube walls with air and you will loose your gas purity. The Indian ones that are flooding Amazon and Ebay are rated for 30 seconds on/30 seconds off duty cycle at a very low current compared to the classical lamps used in education for decades.


Think HENE ballast resistor, exact same circumstances from an engineering standpoint.

There are exceptions to the rule if your using something like a 3KV 20 mA Neon Sign Transformer on a Variac, but for most modern PSUs not designed for lamp service, you'll need a ballast resistor. Determination of the resistor value will need to be done experimentally.

So not just "ANY" HV supply.



Steve

 

[NightLase]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

maybe you can do the comparison and let us know the results !

Hey Guys,

My HgAr Spectral lamp is on its way from Germany. Hopefully be able to provide some images once I receive them.

So, As yet I have not conducted any adjustment of the optics other than removing baffles and the input filter.

This evening I took a spectrum of a Philips "Tornado" CFL Lamp (following around 30 min warm-up).

I have the Spectrometer loaded with Coefficients from HeNe & DPSS laser wavelengths.

Attached the resultant spectrum of the Philips CFL

 

[Agastar]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Hey Guys,

My HgAr Spectral lamp is on its way from Germany. Hopefully be able to provide some images once I receive them.

So, As yet I have not conducted any adjustment of the optics other than removing baffles and the input filter.

This evening I took a spectrum of a Philips "Tornado" CFL Lamp (following around 30 min warm-up).

I have the Spectrometer loaded with Coefficients from HeNe & DPSS laser wavelengths.

Attached the resultant spectrum of the Philips CFL

It looks like yours has a bit wider bandwidth than mine or maybe mine is shifted more towards the blue than the red like yours. Either way, it looks cool and i'm still amazed at how consistent the graphs look from spectrometer to spectrometer and CFL manufactures.

 

[Mosc007]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

It looks like yours has a bit wider bandwidth than mine or maybe mine is shifted more towards the blue than the red like yours. Either way, it looks cool and i'm still amazed at how consistent the graphs look from spectrometer to spectrometer and CFL manufactures.

Unless you have calibration points close to the max and min values of the Spectro you get very inacurate values shown on the Graph at the upper and lower ends. They are only accurate between the outer most calibration points. The polynomial calc goes crazy outside the calibration points.

All CFL tubes should be the same with the main lines. They seem to all use Mercury and Argon.

The variations occur from the added Phosphor inside the tube. Phosphor is easy to notice as it adds a broad range of output as apposed to highly defined lines from the gases.

 

[Agastar]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Unless you have calibration points close to the max and min values of the Spectro you get very inacurate values shown on the Graph at the upper and lower ends. They are only accurate between the outer most calibration points. The polynomial calc goes crazy outside the calibration points.

All CFL tubes should be the same with the main lines. They seem to all use Mercury and Argon.

The variations occur from the added Phosphor inside the tube. Phosphor is easy to notice as it adds a broad range of output as apposed to highly defined lines from the gases.

Thanks, I was not aware that the polynomial calc did that. It makes sense seeing what I have with mine though. Even though I didn't realize that, I did try to get calibration points as close to the ends as possible as well as some in the midle.

I did manage to find my hacked CFL bulb that now runs off of a AA battery and plan to use that in a black box to do some more playing around.

I also picked up some of these gas-discharge tubes from ebay.
Ar & Xe from here & Ne & He from here. Should be fun to play around with

 

[LSRFAQ]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Have some Neutral Neon numbers from the database, in Nanometers this time ..

456.8962
460.7284
462.3908
587.1792
587.2127
589.9114
591.8306
595.9200
598.7056
598.8897
600.0365
602.7263
615.6283
618.6716
619.1023
626.8232
629.7388
735.8962

Steve

 

[LSRFAQ]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Some Xenon lines, Angstroms

5116.46
5127.24
5162.
5164.39
5167.30
5185.85
5206.07
5245.27
5248.98
5251.89
Steve

 

[paul1598419]

Re: B&Wtech 473nm unit / Spectrometer Mods & Info

Dear Paul,
Are you speaking about things like these :

https://www.ebay.com/itm/50kV-High-...m=372235292205&_trksid=p2047675.c100005.m1851

https://www.ebay.com/p/15kv-High-Vo...m=382131734381&_trksid=p2047675.c100005.m1851

https://www.ebay.com/itm/3-7V-DC-Hi...or-Ignition-Coil-Step-up-Module-/112962639760

https://www.ebay.com/p/15kv-High-Vo...Module-DC-5v-15v/17018347618?iid=112953012679

Your help is more than welcome
and thanks again

C

I assumed when I wrote this that you had ampules filled with Nobel gases. I have seen these excited by wrapping a low current HV wire around the ampule to excite it into discharge. You certainly don't want to use ANY high voltage source as some can be very high and if the discharge tube had an anode and cathode, we are talking about a completely different animal. I have seen the 1 kV to 15 kV ones work for this purpose and they are typically <$5.00 each as you have seen. If you just want a He and Ne source and have a He-Ne laser, you can use the glow from the tube as a calibration source.