Claims
- 1. A Q-switched CO2 laser system for material processing, the system comprising:
a plurality of mirrors defining an optical cavity; a gain medium positioned within the optical cavity for generating a laser beam a cavity loss modulator for switching loss within the cavity from a high loss state to a low loss state or a low loss state to a high loss state, generating thereby one or more laser pulses; a pulsed signal generation system connected to the cavity loss modulator for delivering pulsed signals to the cavity loss modulator thereby controlling the state of optical loss within the optical cavity; a control unit connected to the pulsed signal generation system for controlling the pulsed signal generation system; and a pulse clipping circuit receptive of a portion of the laser beam and connected to the pulsed signal generation system for truncating a part of the laser pulses.
- 2. The laser system as set forth in claim 1 wherein the pulse clipping circuit comprises:
a detector receptive of the portion of the laser beam providing thereby an output signal indicative of the laser pulses; a comparator for comparing the output signal of the detector with a reference signal providing thereby an output signal indicative of the greater or lesser of the detector output signal or the reference signal; and a timer receptive of the comparator output signal and operative to provide a timing signal to the pulsed signal generation system for controlling the duration of the pulsed signals delivered to the cavity loss modulator.
- 3. The laser system as set forth in claim 2 further comprising a signal amplifier receptive of the detector output signal providing thereby an amplified detector output signal to the comparator.
- 4. The laser system as set forth in claim 2 further comprising a first bias circuit for setting the value of the reference signal with respect to the output signal of the detector.
- 5. The laser system as set forth in claim 2 further comprising:
a signal delay device receptive of the detector output signal and operative to provide a delayed detector output signal to the comparator; a signal attenuator receptive of the detector output signal and operative to provide an attenuated detector output signal to the comparator.
- 6. The laser system as set forth in claim 5 further comprising a second bias circuit for setting the value of the time delayed detector output signal with respect to the attenuated detector output signal.
- 7. The laser system as set forth in claim 1 further comprising a system for automatically terminating the generation of the laser beam including:
a first polarizing device receptive of the laser beam in a first state of polarization and operative to pass the laser beam in the first state of polarization; a polarization rotator receptive of the laser beam from the first polarizing device in the first state of polarization and operative to change the polarization of the laser beam to a second state of polarization and further operative to direct the laser beam to a workpiece; wherein the polarization rotator is receptive of the laser beam reflected from the work piece in the second state of polarization and operative thereby to change the state of polarization of the laser beam to a third state of polarization; and wherein the first polarization device is receptive of the laser beam from the polarization rotator in the third state of polarization; a detector receptive of the laser beam from the first polarizing device providing thereby an output signal indicative of the reflectance of the work piece; and a comparator for comparing the output signal of the detector with a reference signal, providing thereby an output signal indicative of the greater or lesser of the detector output signal or the reference signal.
- 8. The laser system as set forth in claim 7 further comprising a bias circuit for setting the value of the reference signal.
- 9. The laser system as set forth in claim 7 further comprising a lens for focusing the laser beam from the polarization rotator in the first state of polarization to the work piece and receptive of the laser beam reflected from the work piece.
- 10. The laser system as set forth in claim 7 further comprising a signal amplifier receptive of the detector output signal and providing thereby an amplified detector output signal.
- 11. The laser system as set forth in claim 7 further comprising a logic circuit receptive of the comparator output signal and a command signal from the control unit to Q-switch the laser.
- 12. The laser system as set forth in claim 11 wherein the logic circuit comprises:
a signal inverter for inverting the comparator output signal; and a logical AND gate receptive of the inverted comparator signal and the command pulse providing thereby an output signal to the pulsed signal generation system.
- 13. The laser system as set forth in claim 7 further comprising a second polarizing device receptive of the laser beam from the first polarizing device in the first state of polarization and operative to pass the laser beam in the first state of polarization and further receptive of the laser beam from the polarization rotator in the third state of polarization and further operative thereby to reflect polarization components of the laser beam in the third polarization state to the detector.
- 14. The laser system as set forth in claim 1 further comprising a shutter system connected to the control unit for alternately blocking and passing the laser beam.
- 15. The laser system as set forth in claim 1 wherein the pulsed signal generation system comprises:
a switching circuit receptive of pulsed signals from the pulse receiver operative thereby to charge or discharge the cavity loss modulator; a pulse receiver providing commands to the switching circuit; and a power supply for the pulse receive and the switching circuit.
- 16. The laser system as set forth in claim 15 wherein the power supply comprises:
a power converter connected to the switching circuit and receptive of a constant voltage input signal providing thereby a high voltage output signal to the switching circuit; a power supply controller for controlling the power converter and receptive of a low voltage set point signal; a voltage divider connected to the power converter at the high voltage output signal and to the power controller at the divided voltage and operative thereby to minimize the difference between the high voltage output signal and the low voltage set point.
- 17. The laser system as set forth in claim 1 further comprising a phase grating receptive of the laser beam and operative to diffract a portion of the laser beam away from the laser beam at a prescribed optical order.
- 18. The laser system as set forth in claim 17 wherein the phase grating comprises an acousto-optic cell connected to a signal generator receptive of a pulsed signal from the control unit and operative to generate an acoustically variable phase grating in the acousto-optic cell.
- 19. The laser system as set forth in claim 18 further comprising a signal delay device receptive of the pulsed signal from the control unit for synchronizing the acoustically variable phase grating and the laser pulses.
- 20. The laser system as set forth in claim 15 wherein the switching circuit comprises:
a first switch connected to the power supply and to the cavity loss modulator receptive of a first pulsed signal from the pulse receiver and operative thereby to charge the cavity loss modulator when the first switch is in the closed position; a second switch connected across the cavity loss modulator and receptive of a second pulsed signal from the pulse clipping circuit and operative thereby to discharge the cavity loss modulator when the second switch is in the closed position.
- 21. The laser system as set forth in claim 20 further including an impedance connected to the first and second switch and the cavity loss modulator.
- 22. The laser system as set forth in claim 21 farther comprising an amplifier for amplifying the first and second pulsed signals to the first and second switch.
- 23. The laser system as set forth in claim 20 wherein the first and second switch comprise a metal oxide semiconductor field effect transistor connected to a transformer.
- 24. The laser system as set forth in claim 23 further comprising an impedance connected across the first and second switches.
- 25. The laser system as set forth in claim 1 further comprising:
a first polarizing device positioned within the optical cavity and receptive of the laser beam for polarizing the laser beam; and a second polarizing device positioned within the optical cavity and receptive of the laser beam for changing the polarization of the laser beam.
- 26. The laser system as set forth in claim 25 wherein the second polarizing device is operative to change the polarization of the laser beam from a first state of polarization to a second state of polarization and from the second state of polarization to a third state of polarization.
- 27. The laser system as set forth in claim 26 wherein the second polarizing device is operative to change the polarization of the laser beam from a first state of polarization to a second state of polarization and from the second state of polarization to a third state of polarization when no pulsed signals are delivered to the cavity loss modulator by the pulsed signal generation system.
- 28. The laser system as set forth in claim 26 wherein the second polarizing device is operative to change the polarization of the laser beam from the third state of polarization to the second state of polarization when a non-zero pulsed signal is delivered to the cavity loss modulator by the pulsed signal generation system.
- 29. The laser system as set forth in claim 25 wherein the first polarizing device is a thin film polarizer operative to allow passage of the laser beam therethrough in a first direction within the optical cavity when in the first state of polarization and to reflect the laser beam in a second direction within the optical cavity when in the third state of polarization when the optical cavity is in a high optical loss condition and further operative to allow passage of the laser beam therethrough in the first and second direction within the optical cavity when the optical cavity is in a low optical loss condition.
- 30. The laser system as set forth in claim 25 wherein the second polarizing device is a quarter wave plate.
- 31. The laser system as set forth in claim 25 wherein the second polarizing device is a reflective phase retarder.
- 32. The laser system as set forth in claim 1 wherein the cavity loss modulator comprises:
an optical crystal having an entrance surface receptive of the laser beam and an opposing laser beam exit surface; a first optical window having an optical entrance surface receptive of the laser beam and an opposing laser beam exit surface, the exit surface of the first optical window being in physical contact with the entrance surface of the optical crystal thereby defining a first optical interface; and an optical reflector in physical contact with the laser beam exit surface of the active optical crystal thereby defining a second optical interface, the optical reflector receptive of the laser beam from the optical crystal and operative to redirect the laser beam into the active optical crystal.
- 33. The laser system as set forth in claim 32 wherein the optical reflector comprises a prism.
- 34. The laser system as set forth in claim 32 wherein the optical reflector comprises a second optical window having an optical entrance surface receptive of the laser beam and an opposing reflective surface, the entrance surface of the second optical window being in physical contact with the exit surface of the active optical crystal thereby defining a second optical interface.
- 35. The laser system as set forth in claim 34 wherein the reflective surface comprises a reflecting thin film coating.
- 36. The laser system as set forth in claim 1 wherein the optical cavity includes a multiple pass optical assembly for directing the laser beam through the cavity loss modulator multiple times.
- 37. The laser system as set forth in claim 36 wherein the multiple pass optical assembly comprises:
a first reflective device positioned within the optical cavity and receptive of the laser beam from the cavity loss modulator and operative to redirect the laser beam into the cavity loss modulator; and a second reflective device positioned within the optical cavity and receptive of the laser beam from the cavity loss modulator and an optical cavity mirror and operative to redirect the laser beam into the cavity loss modulator.
- 38. The laser system as set forth in claim 37 further comprising:
a first polarizing device positioned within the cavity for polarizing the laser beam; and a second polarizing device positioned within the cavity for changing the polarization of the laser beam.
- 39. The laser system as set forth in claim 37 wherein the first reflective device is a reflecting thin film or a prism.
- 40. The laser system as set forth in claim 37 wherein the second reflective device is a mirror.
- 41. The laser system as set forth in claim 38 wherein the first polarizing device is a thin film polarizer.
- 42. The laser system as set forth in claim 38 wherein the second polarizing device is a reflective phase retarder.
- 43. A method of maintaining constant phase retardation induced in a laser beam by an electro-optic crystal in a repetitively Q-switched material processing CO2 laser, the method comprising:
maintaining zero voltage across the electro-optic crystal during the high optical loss interval of the Q-switching cycle; and maintaining a prescribed non-zero voltage across the electro-optic crystal during the low optical loss interval of the Q-switching cycle.
- 44. A method of Q-switching a material processing CO2 laser having an electro-optically modulated crystal, the method comprising:
generating a laser beam in a first state of polarization; maintaining zero voltage across the electro-optic crystal during a high optical loss interval of a Q-switching cycle; and maintaining a prescribed non-zero voltage across the electro-optic crystal during a low optical loss interval of the Q-switching cycle.
- 45. The method as set forth in claim 44 wherein maintaining zero voltage across the electro-optic crystal during the high optical loss interval of the Q-switching cycle includes:
changing the first state of polarization to a second state of polarization; and changing the second state of polarization to a third state of polarization.
- 46. The method as set forth in claim 44 wherein maintaining a prescribed non-zero voltage across the electro-optic crystal during the low optical loss interval of the Q-switching cycle includes:
changing the first state of polarization to a second state of polarization; and changing the second state of polarization to a third state of polarization; changing the third state of polarization to the second state of polarization; and changing the second state of polarization to the first state of polarization.
- 47. The method as set forth in claim 45 wherein the first state of polarization is a linear state of polarization and the second state of polarization is a circular state of polarization and the third state of polarization is a linear state of polarization perpendicular to the first state of polarization.
- 48. The method as set forth in claim 46 wherein the first state of polarization is a linear state of polarization and the second state of polarization is a circular state of polarization and the third state of polarization is a linear state of polarization perpendicular to the first state of polarization.
- 49. The method as set forth in claim 45 including:
propagating the laser beam in the first state of polarization through a first polarizing device; propagating the laser beam through the electro-optic crystal a first time; propagating the laser beam through a polarization rotator; reflecting the laser beam in the second state of polarization from a reflecting device; propagating the laser beam through the polarization rotator a second time; and propagating the laser beam in a third state of polarization through the electro-optic crystal a second time; and reflecting the laser beam in the third state of polarization from the first polarizing device.
- 50. The method as set forth in claim 46 including:
propagating the laser beam in the first state of polarization through a first polarizing device; propagating the laser beam through the electro-optic crystal a first time; propagating the laser beam in the second state of polarization through a polarization rotator; reflecting the laser beam in the third state of polarization from a reflecting device; propagating the laser beam through the polarization rotator a second time; propagating the laser beam in the second state of polarization through the electro-optic crystal a second time; and propagating the laser beam through the first polarizing device in the first state of polarization.
- 51. The method as set forth in claim 44 further comprising alternately switching the voltage across the electro-optic crystal from a zero voltage during the high optical loss interval of the Q-switching cycle to a non-zero voltage during the low optical loss interval of the Q-switching cycle.
- 52. A method of Q-switching a CO2 laser for material processing, the laser having a gain medium and a cavity loss modulator, the method comprising:
energizing the gain medium for a first prescribed time duration with a radio frequency pulse having a power equal to an integer multiple of a maximum average radio frequency power; and energizing the cavity loss modulator for a second prescribed time duration causing the laser cavity to switch from a high optical loss state to a low optical loss state generating thereby one or more laser pulses; wherein energizing the cavity loss modulator occurs after a third time duration of one to two population decay times of the upper laser level of the gain medium as measured from first energizing of the gain medium.
- 53. The method as set forth in claim 52 wherein energizing the gain medium for a first prescribed time duration comprises energizing the gain medium for a first prescribed duty cycle wherein the amount of power of the radio frequency pulse applied to the gain medium is approximately equal to the maximum average radio frequency power divided by the duty cycle.
- 54. The method as set forth in claim 52 wherein energizing the cavity loss modulator for a second prescribed time duration comprises alternately energizing and deenergizing the cavity loss modulator.
- 55. The method as set forth in claim 54 wherein alternately energizing and deenergizing the cavity loss modulator comprises alternately energizing and denergizing the cavity loss modulator during the first prescribed time duration.
- 56. The method as set forth in claim 52 further comprising varying the third time duration.
- 57. The method as set forth in claim 56 wherein alternately energizing and deenergizing the cavity loss modulator comprises increasing subsequent energizing amplitudes of the energization of the cavity loss modulator a prescribed number of times during the first prescribed time duration.
- 58. A method of controlling the amplitude of the output pulses of a repetitively Q-switched CO2 laser including a diffraction grating for material processing, the method comprising:
diffracting a portion of the laser output pulses into a diffraction side order; and varying the frequency of the diffraction grating.
- 59. The laser system as set forth in claim 15 further comprising means for manually controlling the power from the power supply to the switching circuit.
- 60. The laser system as set forth in claim 59 wherein means for controlling the power from the power supply to the switching circuit comprises a potentiometer.
- 61. The laser system as set forth in claim 1 further comprising:
a sealed laser head including a waveguide plate positioned within the optical cavity, the waveguide plate including a plurality of waveguide channels arranged in a zig-zag folded pattern for guiding the laser beam therealong between the plurality of mirrors; a housing for housing the plurality of mirrors, the gain medium, the cavity loss modulator, the pulsed signal generation system, the pulse clipping circuit and the sealed laser head; a radio frequency power supply; a first electrode in contact with the radio frequency power supply and with the waveguide plate; a second, low particulate generating, electrode in contact with gain medium within the waveguide channels; a heat exchanger in thermal contact with the second electrode for conducting heat away from the waveguide plate.
- 62. The laser system as set forth in claim 61 further comprising a shutter connected to the control unit operative to block passage of the laser beam.
- 63. The laser system as set forth in claim 61 further comprising a polarizing device for polarizing the laser beam.
- 64. The laser system as set forth in claim 61 wherein the plurality of mirrors are wavelength selective mirrors comprising:
an output coupling mirror having high transmission at non-lasing wavelengths for coupling the laser beam out of the optical cavity; a plurality of laser beam turning mirrors having high reflectivity at lasing wavelengths for directing the laser beam between the waveguide channels; and a feedback mirror providing optical feedback to the laser cavity.
- 65. The laser system as set forth in claim 61 wherein the cavity loss modulator comprises:
first and second optical windows having a prescribed refractive index and receptive of the laser beam; an electro-optic crystal having a laser beam entrance surface and a laser beam exit surface; wherein the electro-optic crystal possesses a refractive index substantially equivalent to the refractive index of the first and second optical windows; wherein the electro-optic crystal is positioned between and in optical and thermal contact with the first and second optical windows at the laser beam entrance and exit surfaces creating thereby first and second optical interfaces; a first conductive electrode connected to the electro-optic crystal and to electrical ground; a second conductive electrode connected to the electro-optic crystal and to a voltage source creating thereby a voltage across the electro-optic crystal.
- 66. The laser system as set forth in claim 65 wherein the electro-optic crystal comprises an optically polished Cadmium Teluride crystal.
- 67. The laser system as set forth in claim 65 wherein the first and second optical windows comprise optically polished Zinc Selinide windows.
- 68. The laser system as set forth in claim 65 wherein the first and second optical windows include anti-reflection coatings on the outer surfaces thereof.
- 69. The laser system as set forth in claim 65 further comprising:
a housing having an interior volume enclosing the electro-optic crystal and the first and second conductive electrodes;
a retaining device positioned within the interior volume to retain the electro-optic crystal and the first and second conductive electrodes fixed within the interior volume; a cushioning device enveloping the electro-optic crystal to absorb acoustic energy of the electro-optic crystal, the cushioning device positioned between the housing and the electro-optic crystal and between the first and second conductive electrodes and the electro-optic crystal.
- 70. The laser system as set forth in claim 69 wherein the cushioning device comprises an Indium strip.
- 71. The laser system as set forth in claim 69 wherein the retaining device comprises a dielectric material.
- 72. The laser system as set forth in claim 69 further comprising a plurality of spring loaded screws for adjusting the retention of the retaining device.
- 73. An electro-optic modulator comprising:
first and second optical windows having a prescribed refractive index and receptive of the laser beam; an electro-optic crystal having a laser beam entrance surface and a laser beam exit surface; wherein the electro-optic crystal possesses a refractive index substantially equivalent to the refractive index of the first and second optical windows; wherein the electro-optic crystal is positioned between and in optical and thermal contact with the first and second optical windows at the laser beam entrance and exit surfaces creating thereby first and second optical interfaces; a first conductive electrode connected to the electro-optic crystal and to electrical ground; a second conductive electrode connected to the electro-optic crystal and to a voltage source creating thereby a voltage across the electro-optic crystal; and an Indium cushioning device for absorbing energy of the electro-optic crystal.
- 74. The electro-optic modulator as set forth in claim 73 wherein the electro-optic crystal comprises an optically polished Cadmium Teluride crystal.
- 75. The electro-optic modulator as set forth in claim 73 wherein the first and second optical windows comprise optically polished Zinc Selinide windows.
- 76. The electro-optic modulator as set forth in claim 73 wherein the first and second optical windows include anti-reflection coatings on the outer surfaces thereof.
- 77. The electro-optic modulator as set forth in claim 73 further comprising:
a housing having an interior volume enclosing the electro-optic crystal and the first and second conductive electrodes and;
a retaining device positioned within the interior volume to retain the electro-optic crystal and the first and second conductive electrodes fixed within the interior volume; wherein the cushioning device envelopes the electro-optic crystal to absorb acoustic energy of the electro-optic crystal, the cushioning device positioned between the housing and the electro-optic crystal and between the first and second conductive electrodes and the electro-optic crystal.
- 78. The electro-optic modulator as set forth in claim 77 wherein the cushioning device comprises a thin strip.
- 79. The electro-optic modulator as set forth in claim 77 wherein the retaining device comprises a dielectric material.
- 80. The electro-optic modulator as set forth in claim 77 further comprising a plurality of spring loaded screws for adjusting the retention of the retaining device.
- 81. The laser system as set forth in claim 1 further comprising a system for automatically terminating the generation of the laser beam including:
a first polarizing device receptive of the laser beam in a first state of polarization and operative to pass the laser beam in the first state of polarization; a second polarizing device receptive of the laser beam from the first polarizing device operative to pass the laser beam in the first state of polarization; a polarization rotator receptive of the laser beam from the second polarizing device in the first state of polarization and operative to change the polarization of the laser beam to a second state of polarization and further operative to direct the laser beam to a workpiece; wherein the polarization rotator is receptive of the laser beam reflected from the work piece in the second state of polarization and operative thereby to change the state of polarization of the laser beam to a third state of polarization; and wherein the second polarization device is receptive of the laser beam from the polarization rotator in the third state of polarization and operative thereby to direct the laser beam away from the optical cavity; a detector receptive of the laser beam from the second polarizing device providing thereby an output signal indicative of the reflectance of the work piece; and a comparator for comparing the output signal of the detector with a reference signal, providing thereby an output signal indicative of the greater or lesser of the detector output signal or the reference signal.
- 82. The laser system as set forth in claim 81 further comprising a bias circuit for setting the value of the reference signal.
- 83. The laser system as set forth in claim 81 further comprising a lens for focusing the laser beam from the polarization rotator in the second state of polarization to the work piece and receptive of the laser beam reflected from the work piece.
- 84. The laser system as set forth in claim 81 further comprising a signal amplifier receptive of the detector output signal and providing thereby an amplified detector output signal.
- 85. The laser system as set forth in claim 81 further comprising a logic circuit receptive of the comparator output signal and a command signal from the control unit to Q-switched the laser.
- 86. The laser system as set forth in claim 85 wherein the logic circuit comprises:
a signal inverter for inverting the comparator output signal; and a logical AND gate receptive of the inverted comparator signal and a command pulse providing thereby an output signal to the pulsed signal generation system.
- 87. The laser system as set forth in claim 81 further comprising a second polarizing device receptive of the laser beam from the first polarizing device in the first state of polarization and operative to pass the laser beam in the first state of polarization and further receptive of the laser beam from the polarization rotator in the third state of polarization and further operative thereby to reflect polarization components of the laser beam in the third polarization state to the detector.
- 88. A method of truncating a portion of a laser pulse emitted by an electro-optically modulated Q-switched CO2 laser for material processing, the method comprising:
detecting the laser pulse; converting the laser pulse into an electrical signal indicative of the laser pulse; comparing the electrical signal to an electrical bias signal; when the electrical signal indicative of the laser pulse is greater than the electrical bias signal, directing a timing device to terminate electro-optic modulation of the laser after a prescribed duration in time.
- 89. The method as set forth in claim 88 further comprising amplifying the converted signal.
- 90. A method of truncating a portion of a laser pulse emitted by an electro-optically modulated Q-switched CO2 laser for material processing, the method comprising:
detecting the laser pulse; converting the laser pulse into an electrical signal indicative of the laser pulse; delaying the converted signal by a prescribed duration in time, generating thereby a delayed signal; attenuating the converted signal by a prescribed value, generating thereby an attenuated signal; biasing the delayed signal with respect to the attenuated signal generating thereby a biased signal; comparing the biased signal with the attenuated signal; when the value of the biased signal equals the value of the attenuated signal directing a timing device to terminate electro-optic modulation of the laser after a prescribed duration in time.
- 91. A method of Q-switching an electro-optically modulated CO2 laser for material processing, the method comprising:
during a high optical loss condition within the laser, energizing an electro-optic crystal within the laser until the electro-optic crystal is fully charged to a high voltage level; terminating energizing the electro-optic crystal; allowing gain to build up within the laser for the cavity build up time; during a low optical loss condition within the laser generating a laser pulse; deenergizing the electro-optical crystal after the laser pulse has been generated; and terminating deenergizing the electro-optical crystal.
- 92. The method as set forth in claim 91 further comprising truncating a portion of the emitted laser pulse.
- 93. The method as set forth in claim 92 wherein truncating a portion of the laser pulse comprises:
detecting the laser pulse; converting the laser pulse into an electrical signal indicative of the laser pulse; delaying the converted signal by a prescribed duration in time, generating thereby a delayed signal; attenuating the converted signal by a prescribed value, generating thereby an attenuated signal; biasing the delayed signal with respect to the attenuated signal generating thereby a biased signal; comparing the biased signal with the attenuated signal; when the value of the biased signal equals the value of the attenuated signal directing a timing device to terminate electro-optic modulation of the laser after a prescribed duration in time.
- 94. The method as set forth in claim 92 wherein truncating a portion of the laser pulse comprises:
detecting the laser pulse; converting the laser pulse into an electrical signal indicative of the laser pulse; comparing the electrical signal to an electrical bias signal; when the electrical signal indicative of the laser pulse is greater than the electrical bias signal, directing a timing device to terminate electro-optic modulation of the laser after a prescribed duration in time.
- 95. The method as set forth in claim 45 including:
propagating the laser beam in the first state of polarization through a first polarizing device; propagating the laser beam through the electro-optic crystal a first time; reflecting the laser beam from a polarization rotator; reflecting the laser beam in the second state of polarization from a reflecting device; reflecting the laser beam from the polarization rotator a second time; and propagating the laser beam in a third state of polarization through the electro-optic crystal a second time; and reflecting the laser beam in the third state of polarization from the first polarizing device.
- 96. The method as set forth in claim 46 including:
propagating the laser beam in the first state of polarization through a first polarizing device; propagating the laser beam through the electro-optic crystal a first time; reflecting the laser beam in the second state of polarization from a polarization rotator; reflecting the laser beam in the third state of polarization from a reflecting device; reflecting the laser beam from the polarization rotator a second time; propagating the laser beam in the second state of polarization through the electro-optic crystal a second time; and propagating the laser beam through the first polarizing device in the first state of polarization.
- 97. A Q-switched CO2 laser system for material processing, the system comprising:
defining an optical cavity;
a gain medium positioned within the optical cavity for generating a laser beam; a cavity loss modulator for switching loss within the cavity from a high loss state to a low loss state or a low loss state to a high loss state , generating thereby one or more laser pulses; a pulsed signal generation system connected to the cavity loss modulator for delivering pulsed signals to the cavity loss modulator thereby controlling the state of optical loss within the optical cavity; a control unit connected to the pulsed signal generation system for controlling the pulsed signal generation system; and a pulse clipping circuit receptive of a portion of the laser beam and connected to the pulsed signal generation system for truncating a part of the laser pulses.
- 98. The laser system as set forth in claim 97 wherein the wavelength selective mirrors are thin film coated mirrors comprising:
an output coupling mirror having high transmission at non-lasing wavelengths for coupling the laser beam out of the optical cavity; a plurality of laser beam turning mirrors having high reflectivity at lasing wavelengths for directing the laser beam between the waveguide channels; and a feedback mirror providing optical feedback to the laser cavity.
- 99. The laser system as set forth in claim 1 further comprising:
a sealed laser head; a second plurality of mirrors within the sealed laser head for guiding the laser beam along a folded zig-zag optical path; a housing for housing the plurality of mirrors, the gain medium, the cavity loss modulator, the pulsed signal generation system, the pulse clipping circuit and the sealed laser head; a radio frequency power supply; first and second electrodes in contact with the radio frequency power supply energizing the gain medium; and a heat exchanger for conducting heat away from the gain medium.
- 100. A CO2 laser system for material processing, the system comprising:
a folded waveguide laser having a plurality of wavelength selective mirrors defining an optical cavity; a gain medium positioned within the optical cavity for generating a laser beam; a cavity loss modulator for switching loss within the cavity from a high loss state to a low loss state or a low loss state to a high loss state , generating thereby one or more laser pulses; a pulsed signal generation system connected to the cavity loss modulator for delivering pulsed signals to the cavity loss modulator thereby controlling the state of optical loss within the optical cavity; and a control unit connected to the pulsed signal generation system for controlling the pulsed signal generation system.
RELATED APPLICATIONS
[0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 60/281,516, which was filed on Apr. 4, 2001 and is incorporated herein by reference.
Provisional Applications (1)
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Number |
Date |
Country |
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60281516 |
Apr 2001 |
US |