Joss Research: Lasers: Dye: A Blue Update
A Joss Research Institute Web Report:
Tuning 7-Diethylamino-4-Methyl-Coumarin in a
Flashlamp-Pumped Organic Dye Laser
(December 17, 2003)
Here are some photos of output from 7-Diethylamino-4-Methyl-Coumarin, running in our surplus Candela SLL250 dye laser. I was unable to tune all the way into the violet because I reached the limit stop on the tuner, but I got pretty close.
Sorry these are somewhat blurry. At some point, if I have time, I will update the page with better ones.
the Joss Research Institute
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Contact Information:
Email: a@b.com, where you can replace a with my first name (jon, only 3 letters, no “h”) and b with joss.
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Last modified: Fri Dec 22 20:20:05 EST 2006
Joss Research Institute Projects: Restoring a Commercial Excimer Laser
A Joss Research Institute Report:
The Questek Impulse 4530 Excimer Laser
(04 June, 2004)
Beginnings
Today we took delivery of a Questek excimer laser, which was actually manufactured by Visx. (If I’ve capitalized that incorrectly, please forgive me; if I find out that it’s wrong, I’ll try to correct it.) I believe that this box was made in 1993; it is much heftier and more solidly made than the room-pressure nitrogen laser that I’ve been working on lately. In fact, this thing must weigh a good 500 lbs. It is rated for the usual excimers (F2, ArF, KrF, XeF, Br2 perhaps, XeCl, probably XeI, and maybe one or two others that are far less commonly used), and for both N2 and CO2, with pulsewidths from 5 ns (N2) up to 1 microsecond (CO2??) and pulse energy up to 4 Joules (I’ll believe it when I see it). I don’t know what kind of optics it has in it, but I’m sure I’ll find out.
(Note, added in proof: Milan Karakas suggests that 98% He / 2% N2 would be an appropriate mix for running this as a nitrogen laser. That sounds about right; but of course the design is not
A Joss Research Institute Page: The Avco-Everett C5000 Nitrogen Laser
Restoring a Damaged Avco-Everett C5000 Head
Part 1: Initial Exploration and Reconstruction
Preliminary notes:
This is the first of three (as of late 2004) pages I’ve devoted to this laser. I’ve had a ton of fun getting it running (this page), rebuilding it to replace the main store when that gave up the ghost, and then rebuilding it again during the last few months, to see whether I can get higher output from it.
Note, added 27 December, 2008: I have just rebuilt this laser again, and it is performing extremely well. If you are more interested in performance than history, you can probably just skip ahead to that page.
Photos, this page: With very few exceptions (one of which is the schematic diagram just below), I have uploaded several sizes of each image. If you click one of the bitty ones, get the medium-sized one, and decide that you want something larger, change the “.lg.” in the filename to either “.vl.” (generally 800×600 px), or “.xl.” (generally 1280×960). The exceptions are cropped images, which will typically have “.c1.” or something similar in their filenames and won’t be available in the largest size(s), and “portrait”- oriented images, which will be
Continuing the Restoration of the C5000: Page 2
Next Phase: New Topology, New Dumper Cap
Preliminary note:
(30 December, 2003)
This is a followon to the page in which I describe my effort to resuscitate a rather dead nitrogen laser that we acquired on eBay a while ago.
I recently brought up a commercial dye laser (also found on eBay), and discovered that although it is a fine device, there are some limitations to what I can run through it. It isn’t particularly suitable for some of the dyes I’d like to test, so I’ve returned to the Avco head, to see whether I can bring it back on line. » Read the rest
Continuing the Restoration of the C5000: Page 3
Rebuilding (Again) the C5000 Nitrogen Laser Head
Next Phase: New Peaker Caps, New Dumper Cap, New Switch
Preliminary note:
(07 July, 2004)
As I say on the previous page, it has been some time since I worked on this laser. We acquired a room-pressure nitrogen laser on eBay, and I was busy with that for a while; then we acquired a Questek excimer laser, and I’ve been fussing with that, as well. (It is being a real pig, and I have been unable to find any documentation on it.)
Lately I’ve been thinking about low-pressure nitrogen lasers, though, and as part of that project set I’ve decided to rebuild the C5000 head again. This time I expect to use Barium Titanate “doorknob” caps in the peaker section, which means it will have somewhat higher capacitance than it did in previous incarnations; I am also thinking about using a 30-nf Maxwell for the dumper / main store. This is still in flux, and I haven’t yet decided whether to use a spark gap or a thyratron as the switch this time. I think, though, that I will put the cap on the distribution bus and the switch outboard. (This will make
Continuing the Restoration of the C5000: Page 4
Rebuilding (Yet Again) the C5000 Nitrogen Laser Head
This Phase: Doorknobs, Version 2
Preliminary notes:
(06 December, 2008)
This version is a reprise of the one on the second page of this set, and as I said on that page it has been quite a while since I worked on this laser. I have, however, thought about it a fair amount, and I have decided that it is time to try again. (Every time I rebuild this thing I learn something from it, even when it doesn’t work as well as I might like.)
Here’s the topology I am using for this rebuild:
I haven’t shown the chokes in the + and – HV lines, which keep the EMP from destroying the power supply and also help mitigate the effect of shorting the output of the power supply every time I fire the laser. I should also point out that I have not bothered with the small starting capacitor that I usually put across the spark gap, because the main store is small enough and fast enough that it didn’t seem necessary. The bleeder resistor, which is part of the original design, prevents you from getting a nasty shock if
Joss Research Institute Web Report: A Doorknob-Cap Nitrogen Laser for Do-It-Yourselfers
A Simple Nitrogen Laser
Using “Doorknob” Capacitors
in an LC-Inversion Circuit,
and Semiconductor Preionization
Primarily Intended for Do-it-Yourself Laser Hobbyists
Abstract:
This page presents the design of a nitrogen laser that is intended for DIY construction; it operates with a mixture of helium and nitrogen at room pressure, and uses a mildly novel semiconductor preionization method adapted from other types of laser. Where possible, it uses parts and materials that can be purchased at a hardware store. The device has active length of about 17″, and overall length of about 24″.
The laser operates at voltages of roughly 12 to 20 kV or perhaps a bit higher; does not require a vacuum pump; and puts out, at full voltage, more than half a millijoule in a pulse that is 5 or 6 nsec long FWHM (Full Width at Half Maximum).
The design is not hard-and-fast, nor is it restrictive. It can be modified at need, or upon desire. It may be scalable, for example, to higher capacitance and/or a longer channel. It may also be possible to switch this laser with a thyratron; thyratrons have much longer turn-on time than spark gaps (several dozen nsec as opposed to 5-15 or
Joss Research Institute Web Report: A Large Doorknob-Cap Nitrogen Laser
“DK Plus”
A Second Simple Nitrogen Laser
Using “Doorknob” Capacitors
in an LC-Inversion Circuit,
Primarily Intended as a Research Tool
Abstract:
This page presents the design and construction of a nitrogen laser that can be built by a Do-It-Yourselfer. It is a scaled-up version of a smaller and simpler previous design.
The laser is constructed, as much as possible, from materials that are available at hardware stores and hobby shops: plastic “lumber”, aluminum rulers, steel rods, compression fittings, pieces of basswood and spruce, etc. I used a commercial spark gap, but it is eminently feasible to build one. The two items used in this design that are not easy for a do-it-yourselfer to construct are the “doorknob” capacitors, which are available from time to time on eBay; and the fused silica windows, likewise an eBay item, though it is possible to use fused silica microscope slides, which I buy from EMS.
This laser uses either nitrogen or a mixture of nitrogen and helium at low pressure (roughly 30-90 Torr each), runs at 25-30 kV, and puts out pulses of more than 1.6 millijoules, lasting ~8 nsec FWHM. This corresponds to average pulse power of 160 kW and (assuming a vaguely
Joss Research: Lasers: Nitrogen: The Molectron Nitrogen Laser; Tuning N2-Pumped Dye Lasers
Joss Research:
The Molectron Nitrogen Laser
and
Tuning a Nitrogen-Pumped Dye Laser
[Note: This page is largely about a commercial laser. If you are interested in building your own, please see the “DKDIY” page instead.]
In the Spring of 2002, we bought a used Molectron N2 laser on eBay. Here are a few photos of the case & controls; if you want more detail you can click any of the small images for a 640×480 px version, or use the text links below the small images.
It proved trivial to bring this machine online, when I finally got to it, in the Spring of 2005 (argh): I removed a broken cable-tie from inside the case, powered it up, and adjusted the thyratron reservoir voltage and the mirror alignment.
Here are two fairly representative traces, taken on 3 June, 2005 using a Tektronix 7104 scope, a 7A26 (if I remember correctly) plugin, and a nice fast photodiode sent » Read the rest