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By Jon Singer on May 4, 2011
Joss Institute Projects:
More Information about TEA Nitrogen Lasers
Please note: this preliminary version is, as of early May, 2011, only just begun, and is extremely incomplete and disordered. If you want further references or you want to ask a question, you will find my email address at the bottom of the page.
About Nitrogen Lasers
The nitrogen laser was discovered in 1963. As far as I can recall, it was the first ultraviolet gas laser, the first pulsed ultraviolet laser, and possibly the first-ever ultraviolet laser. It puts out short pulses of light at a wavelength of about 337.1 nm, a little shorter than the wavelength of an ordinary “blacklight” but not quite short enough to be described as “midwave UV”. This light is not visible, and it is even more dangerous than the light from small visible lasers. In addition, the laser operates on high voltage, so you should ONLY attempt to built it if you are prepared to exercise appropriate safety precautions. (I will list a number of these as we proceed.)
The nitrogen laser has very high gain. Excited nitrogen gas amplifies so well, in fact, that nitrogen lasers can usually operate without any mirrors» Read the rest
By Jon Singer on April 28, 2011
TJIIRRS: Number 21
A Look At Some Room-Pressure (TEA) Nitrogen Laser Designs
(04 April, 2011, ff)
!! WARNING !!
These lasers use high voltages, and capacitors that can store lethal amounts of energy. They put out invisible ultraviolet light that can damage your eyes and skin. It is important to take adequate safety precautions and use appropriate safety equipment with any laser; but it is crucially important with lasers that involve high voltages and/or produce invisible beams!
If you use an open spark gap, you need to be aware that it will destroy your hearing unless you use adequate ear protection. I strongly suggest a pair of earmuffs of the type used by people at rifle and pistol ranges, and it is a good idea to use earplugs in addition to the muffs. If you aren’t using adequate hearing protection, an open spark gap will also give you a nasty headache if you run it for a while.
The nitrogen laser was discovered in 1963. Originally, this laser was operated at moderate pressure, roughly a dozen to a few dozen Torr of nitrogen. Although it fairly quickly became clear that the addition of helium did not interfere, and
By Jon Singer on April 7, 2011
TJIIRRS: Number 2 of an Ongoing Series
In Pursuit of Yohen Tenmoku
Late April, 2005
When you decide to replicate an ancient glaze, there are usually a few paths you can take. If there’s an analysis, for example, you can try making a glaze with that composition and working from there. If there are modern glazes with similar appearance, you can start with one or more of those and tweak.
In the case of Yohen Tenmoku, unfortunately, we don’t quite have either of those options. The ancient glazes are among the rarest of Song pieces; there is an iridescent oilspot bowl (just one) in the Miho Museum, and three bowls in other museums, all of which resemble each other in terms of glaze and effect but are not standard oilspot. (We’ll deal with the Miho Museum’s bowl later: I haven’t even started on that one yet.) There are no shards of either type that I’m aware of, and so there are no analyses. Nobody knows exactly where or when these bowls were made, though I think they are very clearly Jian ware. All of these are designated National Treasures and Important Cultural Objects, if my information is » Read the rest
Joss Research Institute Web Report #16B: Continuing Look into Hollow-Cathode Helium-Metal Laser Designs for the DIYer, part 1
By Jon Singer on April 6, 2011
TJIIRRS Number 16B:
Further Examination of Possible Hollow-Cathode
Laser Designs for the Do-It-Yourselfer
Part 1: Quadrupoles
(01 January, 2011, ff)
Note: A dipole has 2 parts, and it has opposite charges or poles across from each other:
A quadrupole has 4 parts, and it has like charges (or poles) across from each other:
+ - - +
This page describes the process of constructing and debugging several hollow-cathode lasers that are operated as quadrupoles. The first is made of copper tubing, and uses sputtered copper vapor in a helium buffer, probably with a small amount of argon added to it to enhance the sputtering. The second is built of stainless-steel tubing; it will use a mixture of helium and iodine or helium and argon as its active medium, and will not require sputtered metal. If I get really ambitious there may be a third and fourth, formalized versions of the first two, possibly with different insulators.
My effort is to make these lasers relatively easy to construct and operate, and to avoid parts that are expensive, difficult to obtain, or require much machining.
Side note: it became clear to me, in the course of working with
By Jon Singer on March 18, 2011
TJIIRRS: Number 10 of an Ongoing Series;
Inexpensive and Readily Available Laser Dyes for the Do-It-Yourselfer
Commercial laser dyes can cost over $100 per gram, and are out of the reach of most DIY laser builders. Furthermore, most chemical companies refuse to sell to individuals these days. This page explores dyes for DIYers, with an eye toward affordability, availability, and performance. Most of these have been tested with nitrogen laser pumping, and a few have been tested with flashlamp pumping.
Although Fluorescein is often available on eBay, it is not necessarily very pure; moreover, Fluorescein is difficult to excite with a nitrogen laser because it has relatively little absorption at 337 nm. (That however, makes it an interesting candidate for longitudinal pumping.) Rhodamine 6G is occasionally available on eBay, as well. Neither of them is usually of laser-grade purity, but that certainly doesn’t prevent them from lasing.
On rare occasions, a few scintillators are available on eBay. I have managed to acquire and lase both PPO and POPOP. Those, however, are the exceptions to the rule, and they cover only part of the spectrum, so it is important to find materials that DIYers can routinely acquire and use.
By Jon Singer on March 10, 2011
TJIIRRS: Number 5C [New] of an Ongoing Series;
“Theorie und Praxis IIA”:
Revamping the “DKDIY” Laser
(15 August, 2006, ff)
This page details the construction of a nitrogen laser that is a follow-on to the “DKDIY”design I published here a few months ago, along with a “How-To” page. Because this material is being written substantially as a historical track of the project as it is taking place, it is not necessarily organized logically. When the design is fully stabilized I will try to provide a “How-To” page for those who want to build a laser of this type.
(Note, 2006 September 27: Between the “DKDIY” laser and this “DK-Plus” laser, I experimented with a larger design, which operated, but not at the performance level I had expected. This appears to have been caused by several factors, some of which I may explore [and, I hope, correct] by returning to that laser and rebuilding it, now that I have this one working well.)
(Note, 05 October, 2009: I am reworking this laser, and I hope to get somewhat better performance from it than I originally did. There are a number of issues involved in the rework, which I
By Jon Singer on March 10, 2011
The PRA LN-1000 Nitrogen Laser
(24 May, 2004 ff, with some additions in 2010 and 2011…)
The PRA LN-1000 nitrogen laser operates at room pressure, and puts out pulses that are approximately 800 psec long. (At least, that was what the mfr stated. Most room-pressure nitrogen lasers seem to have pulsewidth between about 600 psec and 1 nsec, and I do not yet have an easy way to check, so we’ll leave it as given for now.) The laser is rated to deliver about 1.5 mJ, which corresponds to more than 2 MW peak power. Here are two views of it:
We won this laser on eBay, some time ago. When it arrived I found the key broken off in the lock (fortunately all the way in, so I could turn the switch with a screwdriver); some of the screws were missing from the case, and it was clear that not all was well within.
I dusted out the HV section and tried running the laser. It mostly self-triggered, emitting various snorts and barks, and it only occasionally lased; but it was clearly a real machine and not just a pile of scrap. I disassembled the primary spark
By Jon Singer on March 7, 2011
TJIIRRS: Number 10c of an Ongoing Series;
Naturally Occurring Compounds Suitable for Use as Laser Dyes
Although most organic materials fluoresce at least a little, there are very few naturally-occurring compounds with quantum efficiency above 0.5 or so. This page discusses some of them, and a few with lower efficiency that have nonetheless been lased.
(04 September, 2006)
Aesculin (the modern spelling is Esculin) has been known for many years. It is a hydroxycoumarin compound, related to the umbelliferones. Aesculin can be extracted from the bark and probably the seed husks of Horse-Chestnuts (of which the most commonly grown kind seems to be Aesculus hippocastanum), and presumably also from closely-related species like the various kinds of Buckeye.
Aesculin is brightly fluorescent, particularly in basic solutions. It has been lased and reported in the literature, though only once that I’m aware of. It is a hemolytic toxin, so you shouldn’t eat any horse-chestnuts that you haven’t first crushed and soaked in several changes of boiling water.
I obtained a small quantity of Aesculin Sesquihydrate, and was able to lase it in 95% Ethanol with a small amount of ammonia. Here is a photo:
(The dye cuvette is on
Joss Research Institute Web Report #15, part B: Toward an Affordable DIY Dye Laser, Revamp for Better Efficiency
By Jon Singer on February 14, 2011
TJIIRRS, Report Number 15B:
Toward a Straightforward DIY Flashlamp-Pumped Organic Dye Laser
Step 2: Improvements
(January 5, 2010, ff)
This page details some things I am trying in an effort to enhance the performance of the laser that I described on the previous page.
!! CAUTION !!
This laser uses high voltages, and capacitors that can store lethal amounts of energy. It puts out a laser beam that can damage your eyes and skin, and it uses organic dyes, some of which are known to be quite toxic. It also uses flammable organic solvents.
It is important to take adequate safety precautions and use appropriate safety equipment with any laser; but it is crucially important with lasers that involve high voltages and present a health and/or fire hazard!
1: Overview and Review of Simmering Results
(11 January, 2010)
Harald Noack, of Graz University of Technology, suggested that I try simmering and pre-pulsing the flashlamp. He cited an article in which the authors obtained 20% improvement in lamp performance just by simmering, and obtained further improvements in laser performance (particularly with blue dyes) and lamp lifetime by prepulsing the lamp.
Simmering involves passing a DC current through the lamp. With
By Jon Singer on February 13, 2011
(2004 March 13)
The Chinese have been making wonderful red glazes with copper in them since at least the mid-1400s. There have been various versions at different times, and the history is quite interesting. (There is a fine chapter on copper colorants in Chinese Glazes, by Nigel Wood.) It turns out that the red color is an early example of nanotechnology: it is caused by a colloidal suspension of copper nanocrystals, some tens of nanometers on a side. (I think they range from ~20 to ~200 nm across, but don’t quote me.) Richard Zsigmondy got a Nobel prize in 1925 for achieving a systematic understanding of colloids; he invented the ultramicroscope in the process of his research.
Copper Red glazes are notoriously difficult and fickle. It’s debatable whether this is inherent, but there’s no question that it’s The Usual State of Affairs. I started trying to make a decent, noncrazing Copper Red in 1996 or 1997, and have made Copper Gray, Copper Grayish-Pink, a color that is probably the one the ancient Chinese called “Mule’s Liver”, and various other wretched failures. I’ve even made one that wasn’t too bad — it came out a rich purplish red. (Darker