Carbon Dioxide Gas LasersCarbon Dioxide Gas Lasers
Fredrick BrownFredrick Brown
Spring 2004Spring 2004
OverviewOverview
QuestionsQuestions
Introduction of CO2 Gas lasersIntroduction of CO2 Gas lasers
Gas Flow CO2 LaserGas Flo...
QuestionsQuestions
How do you control the voltage and gasHow do you control the voltage and gas
flow rate in a Flowing Gas...
IntroductionIntroduction
CO2 laser emits an invisibleCO2 laser emits an invisible
infrared beam of a singleinfrared beam o...
Types of CO2 Gas LaserTypes of CO2 Gas Laser
Flowing Gas LaserFlowing Gas Laser
Sealed Tube Gas LaserSealed Tube Gas Laser...
Flowing Gas LaserFlowing Gas Laser
Gas Mixtures are pumped fromGas Mixtures are pumped from
one end of the tube and outone...
Flowing Gas Cont.Flowing Gas Cont.
Power output is typically 40 toPower output is typically 40 to
80 watts/meter of the tu...
Sealed Gas LaserSealed Gas Laser
The typical Sealed CO2The typical Sealed CO2
Laser tube has anLaser tube has an
operating...
Sealed Tube Cont.Sealed Tube Cont.
There are separate controlThere are separate control
loops for the voltage andloops for...
T.E.A. Gas LaserT.E.A. Gas Laser
Most high power CO2 lasers areMost high power CO2 lasers are
constructed using TEA (Trans...
T.E.A. ContinuedT.E.A. Continued
SpecificationsSpecifications
- pulse duration: 15 ns - 20 µs- pulse duration: 15 ns - 20 ...
Power Supplies For CO2 GasPower Supplies For CO2 Gas
LaserLaser
Fig. 12 View of the power supply and a Variac
(autotransfo...
ApplicationsApplications
The beam for a CO2 GasThe beam for a CO2 Gas
Laser produces a veryLaser produces a very
high temp...
Answers to QuestionsAnswers to Questions
1.) How do you control the voltage and gas flow rate in1.) How do you control the...
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Carbon Dioxide Gas Lasers Fredrick Brown

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Carbon Dioxide Gas Lasers Fredrick Brown

  1. 1. Carbon Dioxide Gas LasersCarbon Dioxide Gas Lasers Fredrick BrownFredrick Brown Spring 2004Spring 2004
  2. 2. OverviewOverview QuestionsQuestions Introduction of CO2 Gas lasersIntroduction of CO2 Gas lasers Gas Flow CO2 LaserGas Flow CO2 Laser Sealed Tube CO2 LaserSealed Tube CO2 Laser (T.E.A.) CO2 Laser(T.E.A.) CO2 Laser Power Supplies for CO2 Gas LaserPower Supplies for CO2 Gas Laser ApplicationsApplications Answers to questionsAnswers to questions
  3. 3. QuestionsQuestions How do you control the voltage and gasHow do you control the voltage and gas flow rate in a Flowing Gas CO2 Laser?flow rate in a Flowing Gas CO2 Laser? What is the operating voltage and currentWhat is the operating voltage and current for a typical Sealed CO2 Gas Laser?for a typical Sealed CO2 Gas Laser?
  4. 4. IntroductionIntroduction CO2 laser emits an invisibleCO2 laser emits an invisible infrared beam of a singleinfrared beam of a single wavelength in the form of awavelength in the form of a small, intense beam.small, intense beam. Specifically, CO2 emitsSpecifically, CO2 emits photons at 10.6 and 9.6um.photons at 10.6 and 9.6um. The laser gases for CO2The laser gases for CO2 lasers normally contain alasers normally contain a mixture of helium, nitrogen,mixture of helium, nitrogen, and carbon dioxide. Someand carbon dioxide. Some laser types also require smalllaser types also require small amounts of CO, H2 or Xe inamounts of CO, H2 or Xe in the laser gas mixture becausethe laser gas mixture because of dissociation of gasof dissociation of gas molecules.molecules. http://www.repairfaq.org/sam/laserpic/laserpic.htmhttp://www.repairfaq.org/sam/laserpic/laserpic.htm Fig. 1 Laser warning tag 60 W max for the CO2 beam.
  5. 5. Types of CO2 Gas LaserTypes of CO2 Gas Laser Flowing Gas LaserFlowing Gas Laser Sealed Tube Gas LaserSealed Tube Gas Laser T.E.A. Gas LaserT.E.A. Gas Laser
  6. 6. Flowing Gas LaserFlowing Gas Laser Gas Mixtures are pumped fromGas Mixtures are pumped from one end of the tube and outone end of the tube and out other to provide fresh gas toother to provide fresh gas to replace the CO2 depleted mixreplace the CO2 depleted mix due to the seperation of gasdue to the seperation of gas molecules.molecules. He and N2 are added to theHe and N2 are added to the mixtures to boost efficiencymixtures to boost efficiency the laser.the laser. plovdiv.techno-link.com/ClientsSites/ladec/default.htm Fig. 2 Flowing Gas Laser. Fig. 3 CO2 mix bottle and primary regulator
  7. 7. Flowing Gas Cont.Flowing Gas Cont. Power output is typically 40 toPower output is typically 40 to 80 watts/meter of the tube80 watts/meter of the tube length.length. A device called the VariacA device called the Variac (Variable Transformer)(Variable Transformer) can becan be used for voltage control. Aused for voltage control. A control valve is used to adjustcontrol valve is used to adjust the rate of gas flow.the rate of gas flow. In commercial lasers, theIn commercial lasers, the Variac and the control valve isVariac and the control valve is coupled together so that whencoupled together so that when the voltage is increased thethe voltage is increased the flow valve is opened inflow valve is opened in proportion to the power setting.proportion to the power setting. http://www.elect-spec.com/variacy.htmhttp://www.elect-spec.com/variacy.htm Fig.4 Output voltage Variac.
  8. 8. Sealed Gas LaserSealed Gas Laser The typical Sealed CO2The typical Sealed CO2 Laser tube has anLaser tube has an operating voltageoperating voltage between 3 to 12KV and abetween 3 to 12KV and a operating current of 2 tooperating current of 2 to 15mA DC.15mA DC. A high starting voltageA high starting voltage usually 2-5 times theusually 2-5 times the operating voltage isoperating voltage is needed to initiate theneeded to initiate the discharge.discharge. http://www.repairfaq.org/sam/laserpic/laserpic.htmhttp://www.repairfaq.org/sam/laserpic/laserpic.htm Fig.5 Low voltage sealed CO2 laser Fig.6 Gas discharge tube for Sealed CO2 Laser
  9. 9. Sealed Tube Cont.Sealed Tube Cont. There are separate controlThere are separate control loops for the voltage andloops for the voltage and currents.currents. - Voltage:- Voltage: An auxiliary winding onAn auxiliary winding on the transformer feeds a bridgethe transformer feeds a bridge rectifier and filter capacitorrectifier and filter capacitor which provides a feedbackwhich provides a feedback voltage proportional to thevoltage proportional to the output of the power supply.output of the power supply. - Current:- Current: The current controlThe current control returns the current through areturns the current through a sensing resistor (with a filtersensing resistor (with a filter capacitor) providing a voltagecapacitor) providing a voltage proportional to the tubeproportional to the tube current.current. http://www.repairfaq.org/sam/laserpic/laserpic.htmhttp://www.repairfaq.org/sam/laserpic/laserpic.htm Fig.7 Sealed CO2 Laser connected to power supply.
  10. 10. T.E.A. Gas LaserT.E.A. Gas Laser Most high power CO2 lasers areMost high power CO2 lasers are constructed using TEA (Transverseconstructed using TEA (Transverse Excited Atmospheric) designs. RatherExcited Atmospheric) designs. Rather than having a long tube with athan having a long tube with a electrical discharge along its lengthelectrical discharge along its length and the CO2 gas mixture flowing fromand the CO2 gas mixture flowing from one end to the other, a series ofone end to the other, a series of electrodes and gas inlets are spacedelectrodes and gas inlets are spaced along the tube.along the tube. - Chamber with CO2 laser gas in it.Chamber with CO2 laser gas in it. - Two electrodes run down the length of theTwo electrodes run down the length of the chamber.chamber. - The pulse excites the CO2 laser gas, whichThe pulse excites the CO2 laser gas, which then begins spontaneous emission.then begins spontaneous emission. - A reflector and an output coupler outsideA reflector and an output coupler outside the chamber form the resonating cavity.the chamber form the resonating cavity. - The "TE" in "TEA" comes from the fact thatThe "TE" in "TEA" comes from the fact that the excitation is performed transverse to thethe excitation is performed transverse to the direction of the laser output, as opposed todirection of the laser output, as opposed to down the length of the tube like in thedown the length of the tube like in the Flowing CO2 laserFlowing CO2 laser.. Fig. 8 TEA Diagram Fig. 13 View of a TEA CO2 Laser in operation
  11. 11. T.E.A. ContinuedT.E.A. Continued SpecificationsSpecifications - pulse duration: 15 ns - 20 µs- pulse duration: 15 ns - 20 µs - peak power: 100 kW - 500 MW- peak power: 100 kW - 500 MW - wave length: 9.12 µm - 11.22 µm- wave length: 9.12 µm - 11.22 µm - average power: 5 mW - 150 W- average power: 5 mW - 150 W Fig. 11 Using TEA laser on a uncooperative computer monitor http://www.repairfaq.org/sam/laserpic/laserpic.htmhttp://www.repairfaq.org/sam/laserpic/laserpic.htm Fig. 10 TEA CO2 Laser cutting metal sheet
  12. 12. Power Supplies For CO2 GasPower Supplies For CO2 Gas LaserLaser Fig. 12 View of the power supply and a Variac (autotransformer) for the primary voltage adjustment. Fig. 13 View of the power supply powering up a CO2 laser http://www.repairfaq.org/sam/laserpic/laserpic.htmhttp://www.repairfaq.org/sam/laserpic/laserpic.htm
  13. 13. ApplicationsApplications The beam for a CO2 GasThe beam for a CO2 Gas Laser produces a veryLaser produces a very high temperature thathigh temperature that may be used formay be used for engraving, cutting,engraving, cutting, drilling, marking, weldingdrilling, marking, welding and in various medicaland in various medical applications such asapplications such as dermatology and as adermatology and as a medical tool for producingmedical tool for producing clean cuts with littleclean cuts with little bleeding.bleeding. http://www.repairfaq.org/sam/laserpic/laserpic.htmhttp://www.repairfaq.org/sam/laserpic/laserpic.htm Fig. 14 Laser cuts/breaks and or inscribes based upon power settings Fig. 15 Laser cutting thin piece of wood
  14. 14. Answers to QuestionsAnswers to Questions 1.) How do you control the voltage and gas flow rate in1.) How do you control the voltage and gas flow rate in a Flowing Gas CO2 Laser?a Flowing Gas CO2 Laser? - A device called the Variac can be used for voltageA device called the Variac can be used for voltage control. A control valve is used to adjust the rate of gascontrol. A control valve is used to adjust the rate of gas flow.flow. 2.)2.) What is the operating voltage and current for aWhat is the operating voltage and current for a typical Sealed CO2 Gas Laser?typical Sealed CO2 Gas Laser? -- The typical Sealed CO2 Laser tube has an operatingThe typical Sealed CO2 Laser tube has an operating voltage between 3 to 12KV and a operating current of 2voltage between 3 to 12KV and a operating current of 2 to 15mA DC.to 15mA DC.

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