WO2004105100A2 - Trains d'impulsions d'ablation provenant d'amplificateurs optiques multiples - Google Patents

Trains d'impulsions d'ablation provenant d'amplificateurs optiques multiples Download PDF

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Publication number
WO2004105100A2
WO2004105100A2 PCT/US2004/015913 US2004015913W WO2004105100A2 WO 2004105100 A2 WO2004105100 A2 WO 2004105100A2 US 2004015913 W US2004015913 W US 2004015913W WO 2004105100 A2 WO2004105100 A2 WO 2004105100A2
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Prior art keywords
pulses
pulse
amplifiers
optically
pumped
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PCT/US2004/015913
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English (en)
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WO2004105100A3 (fr
Inventor
Peter Delfyett
Richard Stoltz
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Raydiance, Inc.
The University Of Central Florida Research Foundation
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Priority to US10/916,017 priority Critical patent/US7361171B2/en
Publication of WO2004105100A2 publication Critical patent/WO2004105100A2/fr
Publication of WO2004105100A3 publication Critical patent/WO2004105100A3/fr
Priority to US11/894,867 priority patent/US7963958B2/en
Priority to US12/961,390 priority patent/US8398622B2/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
    • A61B18/20—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using laser
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B2017/00017—Electrical control of surgical instruments
    • A61B2017/00022—Sensing or detecting at the treatment site
    • A61B2017/00057—Light
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00636—Sensing and controlling the application of energy
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B2018/00636—Sensing and controlling the application of energy
    • A61B2018/00904—Automatic detection of target tissue
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/06—Measuring instruments not otherwise provided for
    • A61B2090/061—Measuring instruments not otherwise provided for for measuring dimensions, e.g. length

Definitions

  • the present invention relates in general to the field of light amplification and, more particularly, to trains of ablation pulses from multiple optical amplifiers.
  • Ablative material removal is especially useful for medical purposes, either in-vivo or on the outside surface (e.g., skin or tooth), as it is essentially non-thermal and generally painless. Moreover, ablative material removal essentially exerts no pressure on the surface of the material, so it is quite useful for many other types of cutting and machining. Ablative material removal is generally done with a short optical pulse that is stretched amplified and then compressed.
  • a number of types of laser amplifiers have been used for the amplification, including fiber amplifiers. Fiber amplifiers have a storage lifetime of about 100 to 300 microseconds. While some measurements have been made at higher repetition rates, these measurements have shown an approximately linear decrease in pulse energy. For ablations purposes, fiber amplifiers have been operated with a time between pulses of equal to or greater than the storage lifetime, and thus are generally run a repetition rate of less than 3-10 kHz.
  • Laser ablation is very efficiently done with a beam of very short pulses (generally a pulse-duration of three picoseconds or less). While some laser machining melts portions of the work-piece, this type of material removal is ablative, disassociating the surface atoms. Techniques for generating these ultra-short pulses are described, e.g., in a book entitled “Femtosecond Laser Pulses” (C. Rulliere - editor), published 1998, Springer- Verlag Berlin Heidelberg New York. Generally large systems, such as Ti:Sapphire, are used for generating ultra-short pulses (USP). When high-power pulses are desired, they are often intentionally lengthened before amplification to avoid thermally-induced internal component optical damage.
  • CPA complementary Pulse Amplification
  • ablative material removal with a very short optical pulse is especially useful for medical purposes and can be done either in-vivo or on the body surface, as it is essentially non-thermal and generally painless.
  • the surgical ablation event has a threshold of less than 1 Joule per square centimeter, but occasionally removal of foreign material may require dealing with an ablation threshold of up to about 2 Joules per square centimeter.
  • control of pulse energy density is desirable. It has been found that in optically-pumped amplifiers, this can be done by controlling repetition rate and can be fine-tuned by controlling optical pumping power. In addition, some materials ablate much faster than others and control of the ablation rate is also desirable. Further, it is preferred that ablation rate be controllable independent of pulse energy.
  • the present invention can be used for ablation laser-machining wherein at least one 0.01 to 10 microsecond-long train of pulses are generated.
  • Each pulse has a pulse-duration of 50 femtoseconds to three picoseconds with the pulses being at intervals of 1 to 20 nanoseconds.
  • parallel amplifiers in either type of system provides faster ablation, while providing greater cooling surface area to minimize thermal problems.
  • one or more of the parallel amplifiers can be shut down, allowing more efficient ablation of a variety of materials with different ablation thresholds, as surfaces are most efficiently ablated at an energy density about three times threshold.
  • the use more than one amplifier in parallel a train mode allows step- wise control of ablation rate independent of pulse energy. Pulses may also arrive one or more picoseconds after those from another amplifier.
  • one or more amplifiers can be shut off (e.g. the optical pumping to a optically-pumped amplifier), and there will be fewer pulses per train.
  • 20 amplifiers there would be a maximum of 20 pulses in a train, but many embodiments might use only three or four amplifiers and three or four pulses per train.
  • multiple amplifiers might be run in a staggered fashion, e.g. ON for a first period (of one second or more) and then turned OFF for a second period (again of one or more seconds), and a first period dormant amplifier turned ON during the second period, and so forth, to spread the heat load.
  • a staggered fashion e.g. ON for a first period (of one second or more) and then turned OFF for a second period (again of one or more seconds), and a first period dormant amplifier turned ON during the second period, and so forth, to spread the heat load.
  • the present invention provides a method of ablative material removal from an object, with a short optical pulse that is stretched amplified and then compressed by generating an initial sub-picosecond pulse in a semiconductor pulse generator (e.g. within a man-portable system) and time-stretching the initial pulse, amplifying the stretched pulse and then compressing the amplified pulse, (e.g. wherein the amplifying and compression are done with either a optically-pumped-amplifier and air-path between gratings compressor combination, or a SOA and chirped optically-pumped compressor combination), wherein more than one amplifiers are used in parallel, and pulses are timed to arrive at the object from 1 to 50 nanoseconds apart, and applying the compressed optical pulse to said object.
  • a semiconductor pulse generator e.g. within a man-portable system
  • time-stretching the initial pulse amplifying the stretched pulse and then compressing the amplified pulse, (e.g. wherein the amplifying and compression are done with either a optical
  • material is successively removed from a surface and surfaces exposed by prior removal to create a hole through the object.
  • the amplifying and compressing is done with an optically-pumped-amplifier and air-path between gratings compressor combination, and the sub-picosecond pulses are stretched to between 500 picoseconds and three nanoseconds.
  • More than two optically- pumped (Cr: YAG) amplifiers or more than two semiconductor optical amplifiers may be used in parallel. More than one optically-pumped amplifiers may be used with one compressor.
  • a first set of at least two pulses is timed to arrive at the surface within a 1 to 100 picoseconds time period, and/or a second set of at least two pulses is timed to arrive at the surface 1 to 25 nanoseconds after the first set of pulses.
  • the present invention provides a method of ablative material removal, from a surface by generating an initial sub-picosecond pulses in a semiconductor pulse generator and time-stretching the initial pulse, amplifying the stretched pulses, and then compressing the amplified pulses, wherein more than one amplifiers are used in parallel, and applying the compressed optical pulse to the surface, wherein the compressed pulses from the more than one amplifiers used in parallel are timed to arrive at the surface from 1 to 50 nanoseconds apart.
  • pulse energy density and ablation rate are independently controlled.
  • a set of pulses may be timed to arrive at the surface within a 5 to 50 picoseconds period, and/or pulses within a set of pulses are timed to arrive at the surface from 20 to 50 picoseconds apart.
  • the present invention provides a method of ablative material removal from an object by using more than one amplifiers in parallel to amplify optical pulses, and applying the amplified optical pulse to the object, wherein the pulses from the more than one amplifiers used in parallel are timed to arrive at the object from 1 to 50 nanoseconds apart.
  • the present invention provides a method of ablation laser-machining by generating a train of pulses with more than one amplifier, (e.g.
  • each pulse having a pulse-duration of 50 femtoseconds to three picoseconds), with the pulses being at intervals of 1 to 50 nanoseconds, and directing a beam of the pulses to an object (e.g. a work-piece) with a pulse-energy-density of 0.1 to 20 Joules/square centimeter to produce at least one hole in the work-piece.
  • an object e.g. a work-piece
  • a pulse-energy-density 0.1 to 20 Joules/square centimeter
  • the amplifying and compressing can be done with a optically-pumped-amplifier and air-path between gratings compressor combination, e.g., with the sub-picosecond pulses stretched to between 10 picoseconds and one nanosecond, or the amplifying and compressing can be done with a chirped optically-pumped compressor combination, e.g., with the sub-picosecond pulses stretched to between 1 and 20 nanoseconds.
  • the man-portable system comprises a wheeled cart or a backpack.
  • the optically-pumped amplifier is a Cr:YAG amplifier or an erbium-doped fiber amplifier
  • the air-path between gratings compressor preferably is a Treacy grating compressor.
  • optically-pumped amplifiers are used in parallel, or more than one semiconductor optical amplifiers are used in parallel. More than one optically-pumped amplifiers may be used with one compressor.
  • the present invention also provides a method of ablative material removal, from a surface with a short optical pulse that is stretched amplified and then compressed by generating an initial sub-picosecond pulse in a semiconductor pulse generator and time- stretching the initial pulse, amplifying the stretched pulse and then compressing the amplified pulse, wherein the amplifying and compression are done with either a optically- pumped-amplifier, or a SOA, and wherein more than one amplifiers are used in parallel, and wherein pulses are timed to arrive at the surface from 1 to 50 nanoseconds apart, and applying the compressed optical pulse to the surface.
  • the total pulses per second (the total system repetition rate) from the one or more parallel optical amplifiers is preferably greater than 0.6 million.
  • Ablative material removal with a very short optical pulse is especially useful for many purposes. It has been found, for example, that ablation-type laser-machining can be made vibration-resistant by using a train of pulses from multiple parallel (train-mode amplifiers, each pulse having a pulse-duration of 50 femtoseconds to three picoseconds, with the pulses being at intervals of 1 to 50 nanoseconds. This may be used reliably produce a series of holes in a work-piece. Perforations (adjacent holes through the work- piece) can be produced to allow removal of a portion of the work-piece. The control of pulse energy is desirable.
  • the term "man-portable" means capable of being moved reasonably easily by one person, e.g., as wheeling a wheeled cart from room to room or possibly even being carried in a backpack.
  • the present invention uses sub-picosecond pulses stretched to between 10 picoseconds and one nanosecond, with the stretched pulse either amplified by a fiber-amplifier (e.g., a erbium-doped fiber amplifier or EDFA) and compressed by an air-path between gratings compressor (e.g., a Treacy grating compressor), with the compression creating a sub-picosecond ablation pulse.
  • a fiber-amplifier e.g., a erbium-doped fiber amplifier or EDFA
  • gratings compressor e.g., a Treacy grating compressor
  • the present invention uses a semiconductor optical amplifier (SOA) and a with a chirped fiber compressor, generally with pulses stretched to 1 to 20 nanosecond during amplification.
  • SOA semiconductor optical amplifier
  • the present invention uses a semiconductor generated initial sub- picosecond pulse in either case and preferably a chirped fiber stretcher in either case (to reduce system size for man-portability), and preferably uses a SOA preamplifier to amplify the initial pulse before introduction into the fiber amplifier.
  • a train of pulses is preferably generated by one or more semiconductor-chip diodes.
  • the train of pulses allows a quasi-continuous wave operation that improves system efficiency, e.g., lessening the number of power up-ramps and down-ramps.
  • a line of laser-produced holes (including a circle of small holes to create a large hole) is desired.
  • vibration or other motion can interfere with efficient production of such a hole.
  • the smaller and less expensive lasers can generate a train of femtosecond pulses at intervals of a few nanoseconds for up to a few microseconds without overheating.
  • the lasers e.g., semiconductor-chip diodes
  • the smaller and less expensive lasers can generate a train of femtosecond pulses at intervals of a few nanoseconds for up to a few microseconds without overheating.
  • channeling guides energy down the hole even if the beam and hole centerlines are offset by a few microns, relative motion would have to be many times supersonic to prevent multiple pulses from entering each laser-produced hole.
  • One embodiment of the present invention provides a method of perforation laser- machining that includes generating at least one 0.01 to 10 microsecond-long train of pulses, each pulse having a pulse-duration of 50 femtoseconds to three picoseconds, with said pulses being at intervals of 1 to 20 nanoseconds, and directing a beam of said pulses to a work-piece with a pulse-energy-density of 0.1 to 20 Joules/square centimeter to produce one or more holes in the work-piece.
  • the holes may be, e.g., 10 to 150 micron holes on centers 15 to 300 microns.
  • the train of pulses are 0.05 to 1 microsecond-long; the pulse-duration is 50 femtoseconds to 1 picoseconds; pulses at intervals are 1 to 10 nanoseconds; and the pulse-energy-density is between 1 and 8 Joules/square centimeter on the work-piece.
  • the holes are preferably 20 to 100 micron holes on centers 15 to 200 microns.
  • a 100 femtosecond pulse can be time-stretched to make an optical pulse signal ramp (of, e.g., increasing, wavelength) which is amplified (at comparatively low instantaneous power), and time-compressed into an amplified 100 femtosecond pulse.
  • an optical pulse signal ramp of, e.g., increasing, wavelength
  • time-compressed into an amplified 100 femtosecond pulse e.g., a series of pulses are generated, and thus a series of wavelength-ramps are used (e.g., a "saw-tooth" waveform with 50 "teeth” may be amplified by the SOAs without turning the current off between the teeth).
  • a series of wavelength-ramps e.g., a "saw-tooth" waveform with 50 "teeth” may be amplified by the SOAs without turning the current off between the teeth.
  • the amplifiers are amplifying continuously during the 50-tooth waveform,
  • Semiconductor laser diodes are highly preferred for generating the ultra-short pulses.
  • Semiconductor laser diodes typically are of III-V compounds (composed of one or more elements from the third column of the periodic table and one or more elements from the fifth column of the periodic table, e.g., GsAs, AlGaAs, InP, InGaAs, or InGaAsP). Other materials, such as II- VI compounds, e.g., ZnSe, can also be used.
  • lasers are made up of layers of different III-V compounds (generally, the core layer has higher index of refraction than the cladding layers to generally confine the light to a core).
  • Semiconductor lasers have been described (see Rulliere, Chapter 5). It should be noted that this method works especially with semiconductor-chip diodes. Semiconductor-chip diodes can have high efficiency (e.g., about 50%) and have short energy-storage-lifetimes
  • the ablating energy can be furnished by a single semiconductor optical amplifier (SOA) putting out less than 10 micro- Joules per pulse (which low energy density also limits collateral damage).
  • SOA semiconductor optical amplifier
  • the other types of lasers e.g., Ti:sapphire
  • the energy-storage-lifetimes e.g., in the hundreds of microsecond range
  • semiconductor-chip diodes can provide a microsecond long train of pulses of nearly constant energy with nanosecond spacmgs. Thus while other types of lasers could be used, semiconductor-chip diodes are preferred.
  • the invention applies not only to GaAs and InP (which generates light within it III-V semiconductor structure at a wavelength of about 1550 nm) laser diodes, but also to other semiconductor materials such as II- VT compounds.
  • Ablation is most efficient at about three times the material's ablation threshold, and thus control of pulse energy density for optimum removal efficiency is very desirable. If the spot size is fixed or otherwise known, this can be achieved by controlling pulse energy; or if the pulse energy is known, by controlling spot size.
  • the present invention uses a novel method of controlling the pulse energy by controlling the amplified pulse energy, which is much more convenient than changing the ablation spot size. It has been found that optically-pumped amplifiers are more effective operated at a fraction (e.g., less than about half) of their maximum stored energy. When operated in this manner, the pulse energy can be varied by controlling the repetition rate, as the amount of stored energy in the amplifier increases with the time between pulses.
  • pulse energy control can be done step- wise by controlling repetition rate and can be fine-tuned by controlling optical pumping power.
  • the pulse energy of a semiconductor optical amplifier (SOA) can be adjusted by changing the current thru the amplifier.
  • each off the parallel SOAs preferably has its own compressor and while the amplified pulses may be put into a single fiber after the compressors, reflections from the joining (e.g., in a star connector) are greatly reduced before getting back to the amplifier.
  • a nanosecond spacing of sub-nanosecond stretched pulses eliminates any amplifying of multiple signals at the same time, and a single compressor is preferably used.
  • Fiber amplifiers have a storage lifetime of about 100 to 300 microseconds. While measurements have been made at higher repetition rates, these measurements have shown an approximately linear decrease in pulse energy. For ablations purposes, power fiber amplifiers have generally been operated with a time between pulses about equal to than the storage lifetime (or at greater than the storage lifetime, to avoid thermal problems in the fiber), and thus are generally run a repetition rate of less than 3-10 kHz. Optically-pumped amplifiers are available with average power of 30 W or more.
  • a moderate-power 5 W average power optically-pumped amplifiers have been operated to give pulses of 500 microJoules or more, as energy densities above the ablation threshold are needed for non- thermal ablation, and increasing the energy in such a system, increases the ablation rate in either depth or allows larger areas of ablation or both.
  • the present invention generally runs the optically-pumped amplifier with a time between pulses of a fraction (e.g., one-half or less) of the storage lifetime and uses a smaller ablation spot.
  • the spot is less than about 50 microns in diameter, but the diameter can be 60 or 75 microns and with sufficient power per amplifier, possibly even more (spot sizes herein are given as circle diameter equivalents, a "50 micron" spot has the area of a 50 micron diameter circle, but the spot need not be round).
  • the smaller spot is preferably scanned to get a larger effective ablation area.
  • the present invention also preferably uses parallel optically-pumped amplifiers to generate a train of pulses to increase the ablation rate by further increasing the effective repetition rate (while avoiding thermal problems and allowing control of ablation rate by the use of a lesser number of operating optically-pumped amplifiers).
  • the present invention may use a SOA preamplifier to amplify the initial pulse before splitting to drive multiple parallel optically-pumped amplifiers and another SOA before the introduction of the signal into each optically-pumped amplifier (which allows rapid shutting down of individual optically-pumped amplifiers). Further, the present invention generally operates with pulse energy densities at about three times the ablation threshold for greater ablation efficiency.
  • a 1 nanosecond selected-pulse with an optically-pumped amplifier and air optical-compressor typically gives compression with -40% losses. At less than 1 nanosecond, the losses in a Tracey grating compressor are generally lower. If the other-than-compression losses are 10%, 2 nano Joules are needed from the amplifier to get 1 nanoJoule on the target. Preferably, for safety purposes, 1550 nm light is preferably used.
  • the alternate configuration with a semiconductor optical amplifier (SOA) and a with a chirped fiber compressor, and with pulses stretched to 1 to 20 nanosecond during amplification is run at repetition rates with a time between pulses of more that the very short semiconductor storage lifetime.
  • the present invention uses a semiconductor generated initial pulse.
  • the present invention may use a SOA preamplifier to amplify the initial pulse before splitting to drive multiple amplifiers.
  • the present invention preferably scans the ablation a smaller spot to get a larger effective ablation area, and in many cases the scanned spot is smaller than the above optically-pumped-amplifier case.
  • the present invention preferably uses parallel amplifiers to generate a train of pulses to increase the ablation rate by further increasing the effective repetition rate (while avoiding thermal problems and allowing control of ablation rate by the use of a lesser number of operating amplifiers).
  • the fiber amplifiers are optically-pumped CW (and are amplifying perhaps 100,000 times per second in 1 nanosecond pulses).
  • non-CW-pumping might be used in operating amplifiers, with amplifiers run in a staggered fashion, e.g., one on for a first half-second period and then turned off for a second half-second period, and another amplifier, dormant during the first-period, turned on during the second period, and so forth, to spread the heat load.
  • the present invention can control input optical signal power, optical pumping power of optically-pumped amplifiers, timing of input pulses, length of input pulses, and timing between start of optical pumping and start of optical signals to control pulse power, and average degree of energy storage in optically-pumped amplifier.
  • a 10-micro Joule- ablation pulse could be as short as 2 picoseconds.
  • a 10 picosecond, 10 micro Joule pulse at 500 kHz (or 50 micro Joule with 100 kHz), and, if heating becomes a problem, operating in a train mode and switching fiber amplifiers.
  • one might rotate the running often fiber amplifiers such that only five were operating at any one time (e.g., each on for l/10 th of a second and off for l/10 th of a second).
  • the spot size would be about 20 microns.
  • Another alternative is to have 20 optically-pumped amplifiers with time spaced inputs, e.g., by 1 nanosecond, to give a train of one to 20 pulses.
  • 5 W amplifiers operating at 50 kHz (and e.g., 100 microJoules) this could step between 50 kHz and 1 MHz.
  • the spot size would be about 33 microns.
  • the selected pulse might be 50 to 100 picoseconds long.
  • a similar system with 15 optically-pumped amplifiers could step between 50 kHz and 750 kHz.
  • Another alternative is to have 10 optically-pumped amplifiers with time spaced inputs, e.g., by 1 nanosecond, to give a train of one to 20 pulses.
  • 10 optically-pumped amplifiers with time spaced inputs, e.g., by 1 nanosecond, to give a train of one to 20 pulses.
  • 5 W amplifiers operating at 20 kHz (and e.g., 250 microJoules) this could step between 20 kHz and 200 kHz.
  • post-amplifier optical efficiency and 250 microJoules, to get 6 J/sq. cm on the target the spot size would be about 50 microns.
  • the selected pulse might be 100 to 250 picoseconds long.
  • a similar system with 30 optically-pumped amplifiers could step between 20 kHz and 600 kHz.
  • the pulse generator that controls the input repetition rate of the optically-pumped amplifiers to fine tune energy per pulse to about three times threshold (e.g., from 5 to 50, or 5 to 100, microJoules per pulse).
  • Another alternative is generating a sub-picosecond pulse and time-stretching that pulse within semiconductor pulse generator to give the wavelength-swept-with-time initial pulse for the fiber amplifier.
  • Another alternative is to measure light leakage from the delivery fiber to get a feedback proportional to pulse power and/or energy for control purposes.
  • Measurement of spot size e.g., with a video camera, is useful, and can be done with a stationary spot, but is preferably done with a linear scan.
  • the spot is less than about 50 microns in diameter.
  • the camera is preferably of the "in-vivo" type using an optical fiber in a probe to convey an image back to, e.g., a vidicon-containing remote camera body. This is especially convenient with a handheld beam-emitting probe and can supply its own illumination.
  • Other cameras using an optical fiber in a probe to convey an image back to a remote camera body e.g., a vidicon-containing camera with a GRIN fiber lens, can also be used.
  • Endoscope type cameras can also be used.
  • Smaller ablation areas may be scanned by moving the beam without moving the probe.
  • Large areas may be scanned by moving the beam over a first area, and then stepping the probe to second portion of the large area and then scanning the beam over the second area, and so on.
  • the scanning may be by beam deflecting mirrors mounted on piezoelectric actuators.
  • the system actuators scan over a larger region but with the ablation beam only enabled to ablate portions with defined color and/or area.
  • a combination of time and, area and/or color can be preset, e.g., to allow evaluation after a prescribed time.
  • Ablative material removal is especially useful for medical purposes either in-vivo or on the body surface and typically has an ablation threshold of less than 1 Joule per square centimeter, but may occasionally require surgical removal of foreign material with an ablation threshold of up to about 2 Joules per square centimeter.
  • the use of more than one amplifier in parallel train mode pulseses from one amplifier being delayed to arrive one or more nanoseconds after those from another amplifier. At lower desired powers, one or more amplifiers can be shut off (e.g., the optical pumping to a fiber amplifier), and there will be fewer pulses per train. Thus with 20 amplifiers there would be a maximum of 20 pulses in a train, but most uses might use only three or four amplifiers and three or four pulses per train.
  • the present invention provides a method of system operation for surgical material removal from a body by optical-ablation with controlled pulse energy from a fiber amplifier by determining a size of a spot to be used by the system, wherein the spot is between 10 and 60 microns diameter; setting a repetition rate to give time between pulses of between l and l/10 th the storage time of the fiber amplifier into the system, inputting a pulse-energy-for-material-being-ablated signal into the system; controlling current through one or more fiber-amplifier pump diodes to give a pulse energy density applied to the body is between 2.5 and 3.6 times ablation threshold of the body portion being ablated, utilizing an optical oscillator in the generation of a series of wavelength-swept-with-time pulses, amplifying the wavelength-swept-with-time pulse with the fiber-amplifier, time-
  • the present invention provides a method of surgical material removal from a body by optical-ablation with controlled pulse energy from a optically-pumped pulse amplifier by inputting a nominal spot size signal and a pulse-energy-for-material- being-ablated signal, utilizing an optical oscillator in the generation of a series of wavelength-swept-with-time pulses, primarily controlling pulse energy based on the pulse- energy-for-material-being-ablated signal by either selecting pulses from the oscillator generated series of wavelength-swept-with-time pulses, wherein the fraction of pulses selected can be controUably varied to give a selected pulse repetition rate that is a fraction of the oscillator repetition rate, or passing electrical current through at least one pump diode to generate pumping light, optically pumping the optically-pumped pulse amplifier with the pumping light, and controlling pump diode current; using an ablation spot-size sensor to measure the ablation spot size and dynamically adjusting either the fraction of pulses selected or the pump diode current for changes in ablation spot size from the nominal
  • repetition rate is used to control pulse energy
  • the pre- compression optical amplifier's temperature is controlled by
  • an active mirror is used in the compressor with the amplification of the active mirror being controlled by current of the active mirror's pump-diodes.
  • a semiconductor oscillator is used to generate pulses and in some embodiments a SOA preamplifier is used to amplify the selected pulses before introduction into the optically-pumped pulse amplifier.
  • sub-picosecond pulses of between 10 picoseconds and one nanosecond are used, followed by pulse selection, with the selected pulses amplified by a fiber-amplifier (e.g., a erbium-doped optically-pumped pulse amplifier or EDFA) and compressed by an air-path between gratings compressor (e.g., a Treacy grating compressor), with the compression creating a sub-picosecond ablation pulse.
  • a fiber-amplifier e.g., a erbium-doped optically-pumped pulse amplifier or EDFA
  • gratings compressor e.g., a Treacy grating compressor
  • Compressors could be run with overlapping inputs from more than one amplifier, but reflections from other of the parallel amplifiers can cause a loss of efficiency.
  • a nanosecond spacing of sub-nanosecond pulses minimizes amplifying of multiple signals at the same time, and a single compressor is preferably used.
  • High ablative pulse repetition rates are preferred and the total pulses per second (the total system repetition rate) from the one or more parallel optical amplifiers is preferably greater than 0.6 million.
  • optically-pumped optical pulse amplifiers including, and those used to pump other optical devices
  • lamp-pumped can be controlled by controlling the pumping lamps in a manner similar to that of controlling pump diode current.
  • active-diode diode pump-current is used to control the amplification of an active mirror.
  • optical pump device (diode or lamp) current is controlled either directly or indirectly by controlling voltage, power, and/or energy.
  • controlling current can include shutting off one or more optical pump devices, when multiple pump devices are used.

Abstract

La présente invention présente diverses méthodes d'élimination de matière d'ablation d'un objet. Une de ces méthodes utilise une impulsion optique courte laquelle est étirée, amplifiée et ensuite compressé par génération d'une impulsion initiale sous la picoseconde dans un générateur d'impulsions à semi-conducteurs et par allongement temporel de l'impulsion initiale, par amplification de l'impulsion prolongée et ensuite compression de l'impulsion amplifiée, l'amplification et la compression étant effectuées soit avec une combinaison d'amplificateurs à pompage optique et de compresseur à voie d'air entre les réseaux, soit avec une combinaison de SOA et de compresseur à pompage optique comprimé, dans lesquelles plusieurs amplificateurs sont utilisés en parallèle et les impulsions sont synchronisées pour arriver à la surface avec un décalage de 1 à 50 nanosecondes, et par application de l'impulsion optique compressée à l'objet.
PCT/US2004/015913 2003-05-20 2004-05-19 Trains d'impulsions d'ablation provenant d'amplificateurs optiques multiples WO2004105100A2 (fr)

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US10/916,017 US7361171B2 (en) 2003-05-20 2004-08-11 Man-portable optical ablation system
US11/894,867 US7963958B2 (en) 2003-05-20 2007-08-21 Portable optical ablation system
US12/961,390 US8398622B2 (en) 2003-05-20 2010-12-06 Portable optical ablation system

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US47197103P 2003-05-20 2003-05-20
US47192203P 2003-05-20 2003-05-20
US60/471,971 2003-05-20
US60/471,922 2003-05-20
US50357803P 2003-09-17 2003-09-17
US60/503,578 2003-09-17

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US20090219610A1 (en) * 2005-09-21 2009-09-03 Gerard Mourou Optical Pule Amplifier with High Peak and High Average Power
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US8398622B2 (en) 2003-05-20 2013-03-19 Raydiance, Inc. Portable optical ablation system
US8173929B1 (en) 2003-08-11 2012-05-08 Raydiance, Inc. Methods and systems for trimming circuits
US9022037B2 (en) 2003-08-11 2015-05-05 Raydiance, Inc. Laser ablation method and apparatus having a feedback loop and control unit
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US7486705B2 (en) 2004-03-31 2009-02-03 Imra America, Inc. Femtosecond laser processing system with process parameters, controls and feedback
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US8135050B1 (en) 2005-07-19 2012-03-13 Raydiance, Inc. Automated polarization correction
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US8189971B1 (en) 2006-01-23 2012-05-29 Raydiance, Inc. Dispersion compensation in a chirped pulse amplification system
US8150271B1 (en) 2006-03-28 2012-04-03 Raydiance, Inc. Active tuning of temporal dispersion in an ultrashort pulse laser system
US8232687B2 (en) 2006-04-26 2012-07-31 Raydiance, Inc. Intelligent laser interlock system
US7885311B2 (en) 2007-03-27 2011-02-08 Imra America, Inc. Beam stabilized fiber laser
US8125704B2 (en) 2008-08-18 2012-02-28 Raydiance, Inc. Systems and methods for controlling a pulsed laser by combining laser signals
US10239160B2 (en) 2011-09-21 2019-03-26 Coherent, Inc. Systems and processes that singulate materials

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