Laser scanning method, laser irradiation device, and laser scanning program

Abstract

A laser scanning method including emitting a pulsed laser beam from a distal end of an optical fiber in a liquid medium during a first period, the pulsed laser beam being emitted for generating a bubble at the distal end, stopping emission of the pulsed laser beam from the distal end during a second period, wherein the first period is a period for moving the optical fiber closer toward an operation member disposed parallel to the optical fiber by utilizing contraction of the bubble that comes into contact with or close to the operation member, and wherein the second period is a period for moving the optical fiber away from the operation member.

1 . A laser scanning method comprising:
 emitting a pulsed laser beam from a distal end of an optical fiber in a liquid medium during a first period, the pulsed laser beam being emitted for generating a bubble at the distal end;   stopping emission of the pulsed laser beam from the distal end during a second period,   wherein the first period is a period for moving the optical fiber closer toward an operation member disposed parallel to the optical fiber by utilizing contraction of the bubble that comes into contact with or close to the operation member, and   wherein the second period is a period for moving the optical fiber away from the operation member,   wherein the laser scanning method further comprises:
 changing a frequency of the pulsed laser beam; 
 detecting movement of the optical fiber at each frequency; 
 determining a resonance frequency of the optical fiber based on the detected movement; and 
 determining a timing for emitting the pulsed laser beam from the distal end based on the resonance frequency of the optical fiber. 
   
     
     
         2 . The laser scanning method according to  claim 1 ,
 wherein the optical fiber moves away from the operation member by means of a restoring force of the optical fiber during the second period.   
     
     
         3 . The laser scanning method according to  claim 1 , further comprising:
 emitting the pulsed laser beam from the distal end during a third period subsequent to the second period,   wherein the third period is a period for moving the optical fiber toward the operation member.   
     
     
         4 . The laser scanning method according to  claim 1 ,
 wherein a pulse group including a plurality of the pulsed laser beams are emitted in the first period.   
     
     
         5 . The laser scanning method according to  claim 4 , further comprising:
 changing a pulse-group frequency of the pulse group and a number of pulses therein, the pulse-group frequency being a repetition frequency of the pulsed laser beams in the pulse group, the number of pulses being the number of the pulsed laser beams included in the pulse group;   detecting movement of the optical fiber at each pulse-group frequency and at each number of pulses; and   setting the pulse-group frequency of the pulse group and the number of pulses therein in the first period based on the detected movement.   
     
     
         6 . The laser scanning method according to  claim 1 , wherein a number of pulses is (T 2 /T 3 )+1,
 wherein the T 3  indicates a time from start of the emission of the pulsed laser beam to vanishing of the bubble, and wherein the T 2  indicates a time from a start of emission of a first pulsed laser beam in one pulse group to start of emission of a last pulsed laser beam in the one pulse group, wherein T 2  indicates the time as a time from the start of the emission of the first pulsed laser beam in the one pulse group to a first contact between the bubble and the operation member.   
     
     
         7 . The laser scanning method according to  claim 1 , wherein the first period and the second period are alternately repeated. 
     
     
         8 . The laser scanning method according to  claim 1 , wherein the method increases a vibration amplitude of the distal end of the optical fiber by causing contraction force of the bubble to act on the distal end of the optical fiber multiple times by means of repeating, multiple times, the emission of the pulsed laser beam in the first period to repeat generation and contraction of the bubble. 
     
     
         9 . A laser irradiation device comprising:
 an optical fiber that emits a pulsed laser beam from a distal end thereof in a liquid medium;   a processor comprising a hardware, the processor controlling the laser beam emitted from the optical fiber; and   a movement detector that detects movement of the optical fiber,   wherein the processor is configured to emit the pulsed laser beam from the distal end during a first period, the pulsed laser beam being emitted for generating a bubble at the distal end, and   wherein the processor is configured to stop emission of the pulsed laser beam from the distal end during a second period,   wherein the first period is a period for moving the optical fiber closer toward an operation member disposed parallel to the optical fiber by utilizing contraction of the bubble that comes into contact with or close to the operation member, and   wherein the second period is a period for moving the optical fiber away from the operation member,   wherein the processor is configured to:
 change a frequency of the pulsed laser beam; 
 detect movement of the optical fiber at each frequency based on information from the movement detector; 
 determine a resonance frequency of the optical fiber based on the detected movement; and 
 determine a timing for emitting the pulsed laser beam from the distal end based on the resonance frequency. 
   
     
     
         10 . The laser irradiation device according to  claim 9 ,
 wherein the optical fiber moves away from the operation member by means of a restoring force of the optical fiber during the second period.   
     
     
         11 . The laser irradiation device according to  claim 9 ,
 wherein the processor is configured to emit the pulsed laser beam from the distal end during a third period subsequent to the second period, and   wherein the third period is a period for moving the optical fiber closer toward the operation member.   
     
     
         12 . The laser irradiation device according to  claim 9 , further comprising:
 a support member that supports the optical fiber in a cantilever manner;   a laser oscillator that supplies the pulsed laser beam to the optical fiber; and   a movement detector that detects movement of the optical fiber.   
     
     
         13 . The laser irradiation device according to  claim 9 ,
 wherein the processor is configured to emit a pulse group including a plurality of the pulsed laser beams during the first period.   
     
     
         14 . The laser irradiation device according to  claim 13 ,
 wherein the processor is configured to change a pulse-group frequency of the pulse group and a number of pulses therein, the pulse-group frequency being a repetition frequency of the pulsed laser beams in the pulse group, the number of pulses being the number of the pulsed laser beams included in the pulse group, and   wherein the processor is configured to determine the pulse-group frequency of the pulse group and the number of pulses therein in the first period based on movement of the optical fiber at each pulse-group frequency and at each number of pulses.   
     
     
         15 . The laser irradiation device according to  claim 9 , wherein a number of pulses is (T 2 /T 3 )+1,
 wherein the T 3  indicates a time from start of the emission of the pulsed laser beam to vanishing of the bubble, and wherein the T 2  indicates a time from a start of emission of a first pulsed laser beam in one pulse group to start of emission of a last pulsed laser beam in the one pulse group, wherein T 2  indicates the time as a time from the start of the emission of the first pulsed laser beam in the one pulse group to a first contact between the bubble and the operation member.   
     
     
         16 . The laser irradiation device according to  claim 9 , wherein the first period and the second period are alternately repeated. 
     
     
         17 . The laser irradiation device according to  claim 9 , wherein the method increases a vibration amplitude of the distal end of the optical fiber by causing contraction force of the bubble to act on the distal end of the optical fiber multiple times by means of repeating, multiple times, the emission of the pulsed laser beam in the first period to repeat generation and contraction of the bubble. 
     
     
         18 . A storage medium storing a laser scanning program causing a laser irradiation device to execute:
 emitting a pulsed laser beam from a distal end of an optical fiber in a liquid medium during a first period, the pulsed laser beam being emitted for generating a bubble at the distal end;   stopping emission of the pulsed laser beam from the distal end during a second period,   wherein the first period is a period for moving the optical fiber closer toward an operation member disposed parallel to the optical fiber by utilizing contraction of the bubble that comes into contact with or close to the operation member, and   wherein the second period is a period for moving the optical fiber away from the operation member,   wherein the laser scanning program causes the laser irradiation device to execute:
 changing a frequency of the pulsed laser beam and detecting movement of the optical fiber at each frequency; 
 determining a resonance frequency of the optical fiber based on the detected movement; and 
 determining a timing for emitting the pulsed laser beam from the distal end based on the resonance frequency. 
   
     
     
         19 . The storage medium storing the laser scanning program according to  claim 18 , wherein a number of pulses is (T 2 /T 3 )+1,
 wherein the T 3  indicates a time from start of the emission of the pulsed laser beam to vanishing of the bubble, and wherein the T 2  indicates a time from a start of emission of a first pulsed laser beam in one pulse group to start of emission of a last pulsed laser beam in the one pulse group, wherein T 2  indicates the time as a time from the start of the emission of the first pulsed laser beam in the one pulse group to a first contact between the bubble and the operation member.   
     
     
         20 . The storage medium storing the laser scanning program according to  claim 18 , wherein the first period and the second period are alternately repeated.