Comments for Joss Research Institute http://jossresearch.org Mon, 21 Nov 2011 15:25:13 +0000 hourly 1 http://wordpress.org/?v=3.3 Comment on Joss Research Institute Web Report #16: DIY Hollow-Cathode Lasers by Colin S. Willett http://jossresearch.org/2011/02/13/joss-research-institute-web-report-16-diy-hollow-cathode-lasers/#comment-238 Colin S. Willett Mon, 21 Nov 2011 15:25:13 +0000 http://localhost:8888/jossresearch/?p=67#comment-238 Dear Jonsinger, You might care to read "Introduction to Gas Lasers - Population inversion Mechanisms' by Colin S. Willett. This is a book published by Pergamon Press and was based on my thesis for my PhD in 1967 for the University of London. Though I was not able to obtain laser action in any of the number of hollow cathode discharge devices (HCD's) that I built in the period 1963 through 1967, I have written evidence to show that I was the first to suggest HCD's could be used for producing metal vapor in which laser action could be produced from energy-transfer from inert gases employed as discharge buffer gases. I referred to HCD's as producing metal vapor from "spluttering" rather than the correct term "sputtering!" The idea of using HCD's as sources for metal lasers occurred while I was doing a project on HCD's at the Northampton College of Advanced Technology (CAT), London, England for a Dip. Tech. in Applied Physics that was awarded in 1963. This was after attending an evening presentation by Oliver S. Heavens on lasers. In 1963 I joined Professor Heavens at Royal Holloway College who was then a Reader in Physics of the University of London to work on lasers. Dear Jonsinger,

You might care to read “Introduction to Gas Lasers – Population inversion Mechanisms’ by Colin S. Willett. This is a book published by Pergamon Press and was based on my thesis for my PhD in 1967 for the University of London.
Though I was not able to obtain laser action in any of the number of hollow cathode discharge devices (HCD’s) that I built in the period 1963 through 1967, I have written evidence to show that I was the first to suggest HCD’s could be used for producing metal vapor in which laser action could be produced from energy-transfer from inert gases employed as discharge buffer gases. I referred to HCD’s as producing metal vapor from “spluttering” rather than the correct term “sputtering!” The idea of using HCD’s as sources for metal lasers occurred while I was doing a project on HCD’s at the Northampton College of Advanced Technology (CAT), London, England for a Dip. Tech. in Applied Physics that was awarded in 1963. This was after attending an evening presentation by Oliver S. Heavens on lasers. In 1963 I joined Professor Heavens at Royal Holloway College who was then a Reader in Physics of the University of London to work on lasers.

]]> Comment on Along The Red Temmoku Trail by jonsinger http://jossresearch.org/2011/02/13/along-the-red-temmoku-trail/#comment-173 jonsinger Fri, 11 Nov 2011 05:13:23 +0000 http://localhost:8888/jossresearch/?p=8#comment-173 Hi. Hope dinner ended up being okay. (I'm extremely pleased that you like the "stuff". Here's a short video in which I assemble a nitrogen laser and run it; from parts on the table to laser light, about 3 minutes; overall duration 4:52. Huge file though, because I didn't compress it -- more than 40 MB. http://71.166.254.214/pictures/video/TEA-n2-laser_show-and-tell.mov [If you have any trouble with that, please email me.]) Best -- jon Hi.

Hope dinner ended up being okay. (I’m extremely pleased that you like the “stuff”. Here’s a short video in which I assemble a nitrogen laser and run it; from parts on the table to laser light, about 3 minutes; overall duration 4:52. Huge file though, because I didn’t compress it — more than 40 MB. http://71.166.254.214/pictures/video/TEA-n2-laser_show-and-tell.mov [If you have any trouble with that, please email me.])

Best –
jon

]]> Comment on Joss Research Institute Web Report #21: Room-Pressure Nitrogen Lasers by jonsinger http://jossresearch.org/2011/04/28/joss-research-institute-web-report-21-room-pressure-nitrogen-lasers/#comment-172 jonsinger Fri, 11 Nov 2011 05:10:46 +0000 http://localhost:8888/jossresearch/?p=74#comment-172 I usually use a commercial energy meter head to find the pulse energy. With low-pressure nitrogen lasers, I use a Motorola MRD500 avalanche photodiode to visualize the pulse on an oscilloscope; but with TEA lasers, this is not so easy. I do not currently have a good way of "seeing" the pulse shape, so ordinarily I assume that it is more or less a half-sine with a short tail, and I assume that it has FWHM duration of about 800 psec. If such a pulse has energy of about 1 mJ, it probably has peak power of roughly 1.25 to 1.5 MW. One thing that seems to be crucial for clean discharge and good output, by the way, is preionization. If there is insufficient preionization, it is very difficult to get a spark-free discharge. If you allow the preionizer to take too much of the electrical energy, however, it interferes with the laser. There is a delicate balance between these extremes, and I am currently thinking about the edge profile of my preionizers. Hope this is helpful; I am happy to talk more about it. Best -- jon I usually use a commercial energy meter head to find the pulse energy. With low-pressure nitrogen lasers, I use a Motorola MRD500 avalanche photodiode to visualize the pulse on an oscilloscope; but with TEA lasers, this is not so easy. I do not currently have a good way of “seeing” the pulse shape, so ordinarily I assume that it is more or less a half-sine with a short tail, and I assume that it has FWHM duration of about 800 psec. If such a pulse has energy of about 1 mJ, it probably has peak power of roughly 1.25 to 1.5 MW.

One thing that seems to be crucial for clean discharge and good output, by the way, is preionization. If there is insufficient preionization, it is very difficult to get a spark-free discharge. If you allow the preionizer to take too much of the electrical energy, however, it interferes with the laser. There is a delicate balance between these extremes, and I am currently thinking about the edge profile of my preionizers.

Hope this is helpful; I am happy to talk more about it.

Best –
jon

]]> Comment on Joss Research Institute Web Report #21: Room-Pressure Nitrogen Lasers by davod http://jossresearch.org/2011/04/28/joss-research-institute-web-report-21-room-pressure-nitrogen-lasers/#comment-123 davod Tue, 25 Oct 2011 19:18:08 +0000 http://localhost:8888/jossresearch/?p=74#comment-123 please tell me, what do we calculate the power density or energy of each pulse of transvers excited nitrogen laser? may laser have poor output, like your laser. please tell me, what do we calculate the power density or energy of each pulse of transvers excited nitrogen laser?
may laser have poor output, like your laser.

]]> Comment on Along The Red Temmoku Trail by Ann Hawkins http://jossresearch.org/2011/02/13/along-the-red-temmoku-trail/#comment-108 Ann Hawkins Tue, 18 Oct 2011 22:35:48 +0000 http://localhost:8888/jossresearch/?p=8#comment-108 I should be making dinner or working but I have abandoned what I should be doing to find some pictures of your work and am totally thrilled. I should be making dinner or working but I have abandoned what I should be doing to find some pictures of your work and am totally thrilled.

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