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Homebrew Lasers. Florian Gahbauer. OSA Latvia Student Chapter Seminar November 5, 2007. Disclaimer.
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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
Prof. Csele’s Basic TEA Laserhttp://technology.niagarac.on.ca/staff/mcsele/lasers/LasersTEA.htm
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
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