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Homebrew Lasers. Florian Gahbauer. OSA Latvia Student Chapter Seminar November 5, 2007. Disclaimer.

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Homebrew Lasers

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Homebrew Lasers

Florian Gahbauer

OSA Latvia Student Chapter Seminar

November 5, 2007


Disclaimer

I myself have never made or attempted to make any of the devices described in this presentation or anything like them. Everything that I know about this devices I learned from the internet. Thus, I cannot guarantee the accuracy or safety of the designs. The purpose of this presentation is to present interesting ideas and perhaps stimulate future projects, but anyone attempting to realize these projects will have to take responsibility for their own safety.

At the same time, I have tried to give credit where credit is due, by including links. I apologize, if I have failed to acknowledge any sources of information.


WARNING:

Construction and operation of any laser device is hazardous. Do not attempt to construct or operate a laser without adequate safeguards and safety practices. Most lasers involve high voltages, toxic chemicals, high vacuum, laser radiation and other hazards. The author specifically disclaims any and all liabilities associated with the construction and use of such devices. Designs presented here are in the interests of providing information on operational principles only and do not represent safe nor ANSI safety compliant designs.

http://technology.niagarac.on.ca/staff/mcsele/lasers/LasersTEA.htm


Outline

  • Basic principles of lasers

  • The Nitrogen TEA Laser

  • Different examples of N2 TEA Lasers

  • High Voltage supplies


Basic Principles of Lasers (1):Population Inversion

http://www.unc.edu/~dtmoore/intro2.jpg

http://www.sp.phy.cam.ac.uk/~SiGe/Population%20Inversion.html


Basic Principles of Lasers (2):Stimulated Emission

http://www.jyi.org/volumes/volume3/issue3/features/peterson.html


Typical Laser Schematic

http://www.rp-photonics.com/lasers.html


The TEA Nitrogen Laser

  • Medium: Nitrogen gas (N2)

  • Pump: electric discharge

  • Resonator: not needed

http://www.fineartradiography.com/hobbies/lasers/nitrogen/


N2 TEA Laser Schematic

http://technology.niagarac.on.ca/staff/mcsele/lasers/LasersTEA.htm


N2 Laser Circuit Schematic

http://new-electronics.gr/n2/pic/schem01.html


Advantages of the TEA N2 Laser

  • Can operate in air (72% nitrogen)

  • No optics required

    • Amplification of nitrogen is very high

    • Significant reduction in cost and complexity

  • No vacuum required

  • Parts are generally inexpensive


Disadvantages of the TEA N2 Laser

  • Timing of spark pulse is critical: ns

    • Upper state lifetime: t[ns] = 36/(1+P[torr]/58)

  • Beam profile is not so good and small

    • Hard to use as dye laser pump (1.5mm-2mm)

  • Light output is in UV (337.1 nm)

    • (but fluorescence visible on paper)

  • Some people recommend the N2 laser in vacuum

    • Less critical electronic requirement


Possible Parts List

+ HV supply

http://spt06.chez-alice.fr/00/lasers.htm


Nitrogen Laser by Thomas Rapp(http://pulslaser.de)


Prof. Csele’s Basic TEA Laserhttp://technology.niagarac.on.ca/staff/mcsele/lasers/LasersTEA.htm


Improved TEA Laser by Prof. Csele


Jarrod Kinsey’s TEA Laserhttp://www.jarrodkinsey.com/pages/howtobuild.html


Some Critical Issues

  • Timing of discharge circuit

    • Must be very fast (<2.5 ns at P=1atm)

    • Therefore, must avoid stray inductance in capacitors

  • Alignment of Electrodes

    • Electrodes must be aligned to within micrometers (according to one source)

  • Smoothness of Electrodes

    • Electrodes must be smooth to avoid discharges at sharp edges


Prof. Csele’s Nitrogen Laser


Nitrogen TEA Lasers in Operation

  • Tour of Homemade TEA Laser

    http://www.youtube.com/watch?v=8-_ZgVmi8r4

  • Rapid-firing TEA laser http://www.youtube.com/watch?v=fOcC7FOy0qA


High Voltage Supplies

  • Laboratory High Voltage Supply

  • Laser printer HV supply

  • Ignition coil circuit

  • Fly-back transformer (from TV) circuit

  • Electrostatic generator

  • Flash transformer (from disposable camera)/Cockroft-Walton multiplier

    • Caution: Camera flash circuits can store dangerous amounts of energy in capacitors


Fly-back Transformer

http://www.powerlabs.org/flybackdriver.htm


Fly-back Transformer Circuit

http://technology.niagarac.on.ca/staff/mcsele/lasers/LasersTEA.htm


Ignition Coils

http://www.sentex.net/~mwandel/cannon/sparky.html


Ignition Coil Circuit

http://www.geocities.com/CapeCanaveral/lab/5322/coildrv.htm


Cockroft-Walton Multiplier

http://home.earthlink.net/~jimlux/hv/cw1.htm


Cockroft-Walton Multiplier and Neon Sign Transformer

http://www.rtftechnologies.org/emtech/cockroft-walton.htm


Electrostatic Generator

  • http://www.jarrodkinsey.com/pages/howtobuild.html


Dangers

  • Laser radiation

    • 337.1 nm is in UV, i.e., invisible

  • High Voltage

    • 20 kV but only a few mA

    • Careful of energy stored in capacitors

  • Spark Gap

    • UV

    • Noise: noise can be more damaging than it sounds. Enclose the spark gap or use ear protection


Links

  • Professor Csele’s Site http://technology.niagarac.on.ca/staff/mcsele/lasers/LasersTEA.htm

  • Sam’s Laser FAQ http://repairfaq.ece.drexel.edu/sam/laserfaq.htm

  • Jarrod Kinsey’s Site http://www.jarrodkinsey.com/pages/howtobuild.html

  • Thomas Rapp’s Site

    http://pulslaser.de/


More Information

http://www.osa-latvia.lv


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