Laser device and photoacoustic measurement device comprising the same

Patent metadata

Field	Value
Publication number	US-10243318-B2
Application number	US-201615275697-A
Country	US
Kind code	B2
Filing date	Sep 26, 2016
Priority date	Mar 27, 2014
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

In a laser device and a photoacoustic measurement device including the laser device, the intensity of light at each wavelength made independently controllable. The laser device includes a laser medium which has oscillation wavelengths at a first wavelength and a second wavelength with higher light emission efficiency than at the first wavelength, an excitation section, a first resonator, a second resonator, a Q-value change unit, and a control section. The control section oscillates light having the first wavelength through Q switching when a first delay time has elapsed after the excitation of the laser medium has been started in a case where the oscillation wavelength is the first wavelength, and oscillates light having the second wavelength through Q switching when a second delay time has elapsed after the excitation of the laser medium has been started in a case where the oscillation wavelength is the second wavelength.

First claim

What is claimed is:

1. A laser device comprising:
a solid-state laser medium which has oscillation wavelengths at a first wavelength and a second wavelength with higher light emission efficiency than at the first wavelength;
an excitation section which excites the laser medium;
a first resonator which is a resonator oscillating light having the first wavelength and has the laser medium on an internal optical path;
a second resonator which is a resonator oscillating light having the second wavelength and has a common optical path which is an optical path in common for the first resonator including an optical path, on which the laser medium is disposed;
a Q-value change unit which includes at least a Q-value change part disposed on the common optical path and oscillates light having the first wavelength or light having the second wavelength through Q switching; and
a control section which controls the excitation section and the Q-value change unit,
wherein the control section controls the Q-value change unit to oscillate light having the first wavelength through Q switching when a first delay time has elapsed after the excitation of the laser medium has been started in a case where the oscillation wavelength is the first wavelength,
the control section controls the Q-value change unit to oscillate light having the second wavelength through Q switching when a second delay time, at which the intensity of light having the second wavelength is less than maximum intensity, has elapsed after the excitation of the laser medium has been started in a case where the oscillation wavelength is the second wavelength, and
the control section changes the set value of the first delay time or the second delay time according to the amount of excitation energy applied to the laser medium by the excitation section.

2. The laser device according to claim 1 ,
wherein the first delay time and the second delay time are set to values such that the intensity of light having the first wavelength and the intensity of light having the second wavelength are equal to each other.

3. The laser device according to claim 1 ,
wherein the first delay time is set to a value such that the intensity of light having the first wavelength becomes the maximum intensity.

4. The laser device according to claim 1 ,
wherein the excitation section includes a flash lamp as an excitation light source, and
the control section changes the set value of the first delay time or the second delay time according to a charging voltage of the flash lamp.

5. The laser device according to claim 4 ,
wherein the control section has a first reference table in which the charging voltage and the set value of the first delay time or the second delay time are associated with each other, and changes the set value of the first delay time or the second delay time based on the first reference table.

6. The laser device according to claim 1 ,
wherein the excitation section includes an excitation light source, and
the control section changes the set value of the first delay time or the second delay time according to a use duration of the excitation light source.

7. The laser device according to claim 6 ,
wherein the control section has a second reference table in which the use duration and the set value of the first delay time or the second delay time are associated with each other, and changes the set value of the first delay time or the second delay time based on the second reference table.

8. A laser device comprising:
a solid-state laser medium which has oscillation wavelengths at a first wavelength and a second wavelength with higher light emission efficiency than at the first wavelength;
an excitation section which excites the laser medium;
a first resonator which is a resonator oscillating light having the first wavelength and has the laser medium on an internal optical path;
a second resonator which is a resonator oscillating light having the second wavelength and has a common optical path which is an optical path in common for the first resonator including an optical path, on which the laser medium is disposed;
a Q-value change unit which includes at least a Q-value change part disposed on the common optical path and oscillates light having the first wavelength or light having the second wavelength through Q switching; and
a control section which controls the excitation section and the Q-value change unit,
wherein the control section controls the Q-value change unit to oscillate light having the first wavelength through Q switching when a first delay time has elapsed after the excitation of the laser medium has been started in a case where the oscillation wavelength is the first wavelength,
the control section controls the Q-value change unit to oscillate light having the second wavelength through Q switching when a second delay time, at which the intensity of light having the second wavelength is less than maximum intensity, has elapsed after the excitation of the laser medium has been started in a case where the oscillation wavelength is the second wavelength,
the first resonator is constituted of a first mirror and a second mirror opposed to each other with the laser medium sandwiched therebetween,
the second resonator is constituted of the first mirror and a third mirror opposed to the first mirror with the laser medium and the second mirror sandwiched therebetween,
the Q-value change unit is constituted of a first Q-value change section which is disposed on the common optical path, and a second Q-value change section which is disposed between the second mirror and the third mirror, and
at least one of the first mirror, the second mirror, and the third mirror is movable along an optical axis direction.

9. The laser device according to claim 8 ,
wherein the control section changes the set value of the first delay time according to the resonator length of the first resonator or changes the set value of the second delay time according to the resonator length of the second resonator.

10. The laser device according to claim 9 ,
wherein the control section has a third reference table in which the resonator length of the first resonator and the set value of the first delay time are associated with each other and a fourth reference table in which the resonator length of the second resonator and the set value of the second delay time are associated with each other, changes the set value of the first delay time based on the third reference table, and changes the set value of the second delay time based on the fourth reference table.

11. A laser device comprising:
a solid-state laser medium which has oscillation wavelengths at a first wavelength and a second wavelength with higher light emission efficiency than at the first wavelength;
an excitation section which excites the laser medium;
a first resonator which is a resonator oscillating light having the first wavelength and has the laser medium on an internal optical path;
a second resonator which is a resonator oscillating light having the second wavelength and has a common optical path which is an optical path in common for the first resonator including an optical path, on which the laser medium is disposed;
a Q-value change unit which includes at least a Q-value change part disposed on the common optical path and oscillates light having the first wavelength or light having the second wavelength through Q switching; and
a control section which controls the excitation section and the Q-value change unit,
wherein the control section controls the Q-value change unit to oscillate light having the first wavelength through Q switching when a first delay time has elapsed aft

Assignees

• Fujifilm Corp

Inventors

• Murakoshi Dai
• Irisawa Kaku
• Tada Takuji

Classifications

• H01S3/1633

  BeAl2O4, i.e. Chrysoberyl · CPC title

• H01S3/106

  by controlling devices placed within the cavity ({H01S3/10076,} H01S3/13 take precedence) · CPC title

• H01S3/092

  of flash lamp (H01S3/0937 takes precedence {; flash lamps per se H01J61/80; circuit arrangements for operating flash lamps in general H05B41/30}) · CPC title

• H01S3/127 Primary

  Plural Q-switches · CPC title

• A61B5/0095

  by applying light and detecting acoustic waves, i.e. photoacoustic measurements · CPC title