Transcript Homebrew Lasers

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
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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 Laser
http://technology.niagarac.on.ca/staff/mcsele/lasers/LasersTEA.htm
Improved TEA Laser by Prof. Csele
Jarrod Kinsey’s TEA Laser
http://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
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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
d
 E  ds   dt
http://www.sentex.net/~mwandel/cannon/sparky.html
Ignition Coil Circuit
http://www.geocities.com/CapeCanaveral/lab/5322/coildrv.htm
Cockroft-Walton Multiplier
Eout  2 * Eac * Nstages
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