By Jon Singer on May 24, 2011
TJIIRRS: Number 22
Some Adventures with a Commercial Excimer-Laser Head
(21 May, 2011, ff)
Some time ago we were able to acquire, on eBay, an item that is clearly the head of a very small excimer laser. It has room for two preionizers; but when we got it, only one was present, and the other edge of the cathode had a white deposit on it that I was uneasy about.
(The deposit is not visible in these photos.)
For quite a while I didn’t do anything with this structure, but it has been on my mind a lot, and a few days ago I dragged it out and started thinking about it in earnest. I usually avoid commercial parts, but here was this very fine piece of equipment, lacking only a few capacitors, a switch, and some gas; and I do have a project or two in mind that could use it.
Beginning of the Build
I have started to build a box for the head:
I have also made a new preionizer for it:
(I got some 5-mm borosilicate tubing on eBay. The vendor specified it as having 3.4-mm ID, but a 1/8″ rod failed to fit » Read the rest
By Jon Singer on May 23, 2011
TJIIRRS, Report Number 15A:
Toward a Straightforward DIY Flashlamp-Pumped Organic Dye Laser
Step 1, First Proof of Principle: A Minimalist Machine
(Is it possible to threshold a dye laser with only 6 Joules input?)
(December 19, 2009, ff)
This page details the construction of a prototype dye laser that is intended for initial checking of some parameters for example, I want to know whether a simple design will threshold “easy” dyes with minimal input energy. In principle, the answer is already known to be “Yes”; but in practice it may not be so easy. The laser will be operating close to margins, and any sacrifice of efficiency will be difficult to work around.
This preliminary design uses a commercial capacitor and a commercial spark gap switch, both of which I hope to eliminate in later designs. The machine that I’m working toward will almost certainly use a commercial flashlamp, though, because xenon is the most efficient emitter in the wavelength regions of interest for pumping organic dyes.
It will, very likely, also use commercial laser mirrors. Quite a few dye lasers have been operated with simpler mirrors, which could be homebrewed, but I am not at all certain
By Jon Singer on May 21, 2011
Interim Research Reports
The Joss Research Institute
- Recent Ceramic Happenings, early Spring, 2005
- Yohen Tenmoku and a plant note or two, late April, 2005
- Bringing up the Molectron Nitrogen Laser
- Results of a Late Spring Δ10 Gas Reduction Firing
- Thoughts About High-Performance Nitrogen Lasers, with a set of follow-on pages in which I actually try to do something about it.
- Item #6 is on hold at the moment.
- “Platzepuss”: An electric-powered radio-control motorized Platz-Gleiter model (Work in progress, currently on hold while I deal with other issues.)
- The Hughes “M-60” rangefinder laser (Likewise on hold for a bit.)
- An Ultraviolet Laser Dye
- Inexpensive Laser Dyes for Do-It-Yourselfers, with follow-ons about pumping and tuning
- A brief report on one way to construct a dye cuvette for nitrogen- or excimer- laser pumping
- A simple and straightforward 5″ refracting RFT built from surplus lenses, PVC pipe (or leftover wood veneer), and a few other things…
- Some Handy Techniques, including a mirror mount that is entirely built from pieces you can buy at a hardware store and a hobby shop…
- An RGB “White Light” dye laser using a single cuvette of dye solution…
- Toward a Simple and Straightforward Lamp-pumped Organic Dye Laser, Part
By Jon Singer on May 10, 2011
TJIIRRS: Number 5 of an Ongoing Series;
Nitrogen Laser Considerations for the DIYer,
With a View Toward the Design and Construction
of a High-Performance DIY Laser
Part 1 of a Multipart Report (see Links)
(16 September, 2009: this is a 2006 rewrite and continuing revision of a page I originally wrote in July of 2005.)
I have been rereading some papers on nitrogen and excimer lasers, and rethinking my understanding of the important characteristics of a nitrogen laser. Some of the issues are simple and some are fairly obvious, but some are not so easy to understand. This page attempts to examine and clarify issues pertinent to DIY high-performance nitrogen lasers, and to take a look at what you need to know in order to build one. Follow-on pages examine specific designs and the performance that you can expect to achieve with them.
If you want a high-performance nitrogen laser and you can’t afford to buy one, it is certainly possible to construct one; but even if you start with a good design, there is only a modest chance that you will obtain the specified performance level on your initial attempt. The nitrogen laser is not a high-tech device, but
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 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