TJIIRRS

Joss Research Institute Web Report #15, part B: Toward an Affordable DIY Dye Laser, Revamp for Better Efficiency

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

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Joss Research Institute Web Report #16: DIY Hollow-Cathode Lasers

TJIIRRS: Number 16

A Hollow-Cathode Laser Design for the Do-It-Yourselfer

(16 February, 2010, ff)

Introduction/Abstract

(22 October, 2010, ff)

This pageset deals with two sorts of hollow-cathode lasers: metal vapor (excluding iodine for the moment), and argon or iodine. The designs are nearly identical, except that the metal vapor lasers must provide metal for the discharge, and in a hollow-cathode laser of this sort the metal is sputtered from the electrodes; argon and iodine are introduced with the buffer gas, which is helium. (Iodine has been classed as a metal vapor laser, and in fact I believe it was the first laser of the helium-metal type to be described in the literature.)

My hope is to generate designs that DIYers can reasonably hope to build and operate. The first one will probably operate with a mixture of helium and argon. If I can get that to work well, I will probably try it with helium and iodine. After that, I hope to move to helium and zinc, perhaps with a small amount of argon to help sputter the zinc into the discharge, and finally helium and copper, also possibly with a small amount of argon.

[Note,

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The Joss [Research] Institute Interim Research Report Series: Web Report #1

TJIIRRS: First Web-based Report (#001)

Putting these reports on the Web should facilitate distribution, and will make it unnecessary for me to send out overly long email messages. It also provides an automatic archive.

Essentially Entirely Ceramics this time,
Early Spring, 2005

Just before the NCECA conference this year, I was privileged to take a workshop with Ruthanne Tudball, who came in from England. Her work is entirely different from mine, and it was a real trip to watch her and talk with her.

Ruthanne spent most of her first eight years as a potter self-taught, in a tiny basement workshop that barely had room for a wedging table and a wheel, so she was unable to fire her work. She’d make something, and put it into the scrap bucket so she could recover and reuse the clay. She couldn’t afford to get attached to any of her pieces. I find the whole business kinda staggering.

NCECA itself took place in Baltimore, in March. As always, it was very good. I got to talk with some extremely knowledgeable people, and picked up good information on several subjects. I also donated pieces to two of the benefit auctions, and participated in

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Joss Research Institute Web Report #19: A Voss Electrostatic Generator

TJIIRRS: Number 19

A Voss Machine

(04 July, 2007)

There are lots of interesting designs for electrostatic generators. The most common and familiar type of “influence machine”, these days, is the Wimshurst machine, but that has counterrotating disks, and is slightly complex. This is not to say that Wimshurst machines are really all that difficult to construct (see this page by Jarrod Kinsey for an example); but I decided to go with something simpler for now. This page records my construction of a Voss machine, with photos and with my comments and occasional suggestions about the various issues I encountered.

I have also provided a link (near the bottom of the page) to a site where you can find a lot of information about many kinds of electrostatic generators.

In its simplest form, the Voss or Töpler-Holtz machine has only a single rotating disk, and when correctly designed and constructed it provides more than adequate performance. In fact, multiple Voss machines (another example) were sometimes used at the turn of the 20th century to power X-ray machines.

(Unless they have corrected it, btw, there is an error in the description of the first photo on the Kenyon page. It

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Joss Research Institute Web Report #8

TJIIRRS: Number 8 of an Ongoing Series;

The Hughes Rangefinder Laser

(27 December, 2005, ff)

We have acquired one of these units, often referred to as “M-60” lasers, though that is not actually the correct designation for them (I believe that they are mostly designated AN/VVS-1), from The Highly Esteemed Nortius Maximus. It is in very nice condition, though lacking electronics. My hope is to bring it up, first with the Q-switch held at the firing position, and later with the switch running. Here are some photos, for reference.


First, top and side views of the entire device:

               


Next the rear reflector (a prism) seen from behind, with the end of the ruby rod partly visible in the background and a bit of the etalon visible on the right side, through the output port (we do not have the beam-expander telescope); then the Q-switch (upper prism) in firing position, so that it faces the etalon and the other prism (which, in turn, faces the ruby rod); and the rear face of the Q-switch prism, which turns out to be coated. In fact, all three faces of the Q-switch are coated.

               


A look at light bouncing off the etalon (which

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Joss Research Institute Web Report #16A: Preliminary Attempt to Build a Stainless-Steel Hollow-Cathode Helium-Argon Laser

TJIIRRS: Number 16A

An Initial Attempt at Building a Hollow-Cathode He-Ar Laser


1. Design Considerations

(~22 October, 2010, ff)

This page describes the process of constructing a small hollow-cathode laser that has argon ions as its active medium, and uses helium as a buffer gas. My objective is to make the laser relatively easy to construct and operate, and to avoid parts that are expensive, difficult to obtain, or require much machining.

I also hope to use this platform to test a helium-iodine mixture, so I will be using stainless steel end fittings, as iodine reacts with brass. If you decide to build one of these and you do not intend to put iodine into it, you can use brass fittings.

This laser should operate at 476.5 nm, close to the usual blue argon wavelength (488.0). The gain is likely to be relatively low, perhaps 6% per meter, but He-Ar hollow-cathode lasers with active regions as short as 10 cm have been successfully operated, and the active length of this prototype will be 30.5 cm, so there is a decent chance that it will be feasible. I expect to use ordinary argon-laser mirrors, which should provide adequate feedback if

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Joss Research Institute Web Report #3

TJIIRRS: Number 3 of an Ongoing Series

(First, a brief note: there is apparently an article on Yohen Tenmoku in a newish Japanese pottery magazine, which covers the work of no fewer than ten artists. I am trying to get my hands on a copy.)

[Note, added in proof, late 2008: I have a copy, and a Japanese friend is trying to translate the article for me.]

The Molectron Laser
11 & 12 May, 2005

Some time ago, we acquired a smallish Molectron nitrogen laser on eBay. It languished for a while, sitting on a “lasers we haven’t gotten to yet” shelf, but a couple days ago I made some space on the bench and set it there.

There was something rattling around loose in it, and I had to open it up anyway, to get a sense of the guts; the loose object proved to be a broken cable tie, which I removed.

Here’s the control panel of the device. Sorry about the lighting — I left the camera’s white balance set to “cloudy” through most of this, to get the best color rendition of the output.

You’ll notice that the pressure is just over 30 Torr. That’s about

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Joss Research Institute Web Report #20: The Hunt for Red Tenmoku

TJIIRRS: Number 20

Red Temmoku: A Difficult Glaze

(2010.0712)

When I first started making my own glazes, I read Robert Tichane’s book about Ash Glazes. In his discussion of Jian teaware he mentions having been given a chip of glaze, and (assuming I remember this correctly) he says that in transmission it was a brownish yellow color. Jian teaware, however, looks almost black. This is because the bowls are made of a dark stoneware-type clay, and a brownish yellow glaze looks really dark on them; I am using porcelain, and a glaze of that sort is not anywhere near as interesting, at least to me.

The Metropolitan Museum of Art, in NYC, has a photo of a particularly lovely “Hare’s Fur” piece on its Website. As you can see, aside from the crystalline formations that give it the appearance of fur, the glaze appears quite dark.

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Joss Research Institute Web Report #9: Our First UV Dye Laser

TJIIRRS: Number 9 of an Ongoing Series;

PPO: A UV Laser Dye That Can Be Pumped by a Nitrogen Laser

(26 January, 2006)

Background:

2,5-Diphenyloxazole, commonly known as PPO, is a very efficient laser dye that has its output primarily in the long UV, at and around 365 nm. (I am hoping that I will be able to tune it to the edge of the visible range.) PPO is fairly easily pumped by nitrogen lasers. We recently acquired a small amount of scintillation-grade PPO on eBay. (Unfortunately the vendor from whom we purchased it appears to be gone as of Autumn, 2007.)

This material has not been purified to laser-grade standards, but as you can see, that doesn’t prevent it from lasing. We probably aren’t getting as much power from it as we might, and the tuning range is almost certainly narrower than the literature would suggest, but the price and availability more than make up for those shortcomings.

PPO is relatively nonpolar. Unlike the usual visible laser dyes, most of which dissolve nicely in alcohols and other polar solvents, even water, PPO dissolves most easily in hydrocarbons. Because I don’t happen to have any petroleum ether or cyclohexane on

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Joss Research Institute Web Report #4

TJIIRRS: Number 4 of an Ongoing Series;
Recent Results, Rutile Blue and a Glaze Test

(22 May, 2005)

First, however, a small note: I have been thinking about bringing up one of our old pulsed YAG heads, using an etalon to narrow the bandwidth for reasonable coherence length, Q-switching it for reasonably brief duration, and jamming the output through a doubling crystal so I can do some pulsed holography. The Q-switch will probably have to be passive; I wonder about coffee (which can apparently Q-switch ruby, according to one story I’ve heard from before my time with lasers) or perhaps a thin slice of brown beer-bottle glass… have to do some testing, I guess, to see whether either of those has any potential for use as a saturable absorber at 1064 nm.


Here are two pieces I fired to about Δ 10 today in moderate reduction:

       
       

Both of them are glazed with Joss Research “New Blue”. The little bowl warped pretty severely, but the colors are really sweet, and it’s kinda cute despite the warpage, or perhaps partly because of it. The platter is a bit heavy, but them’s the breaks; it worked really well, and I’m quite pleased with

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