Laser system and laser light generation method

• US 8,675,700 B2
• Filed: 03/22/2012
• Issued: 03/18/2014
• Est. Priority Date: 03/28/2011
• Status: Active Grant

• Current Assignee: Gigaphoton, Inc. (Komatsu)
• Original Assignee: Gigaphoton, Inc. (Komatsu)
• Inventors: Watanabe, Shuntaro, Onose, Takashi, Wakabayashi, Osamu
• Primary Examiner(s): Park, Kinam
• Application Number:
  US13/427,556
• Publication Number:
  US 20120250709A1
• Time in Patent Office: 726 Days
• Field of Search: 372/25, 372/57, 372/55, 372/9
• US Class Current: 372/25
• CPC Class Codes: H01S 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108
• CPC Class Codes: H01S 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/025 of solid state lasers, e.g. housings or mountings
• CPC Class Codes: H01S 3/10053 Phase control
• CPC Class Codes: H01S 3/1636 Al2O3 (Sapphire)
• CPC Class Codes: H01S 3/2316 Cascaded amplifiers
• CPC Class Codes: H01S 3/2333 Double-pass amplifiers
• CPC Class Codes: H01S 3/2366 comprising a gas as the active medium H01S3/10092, H01S3/2383 take precedence

Abstract

A laser system in this disclosure may include: a master oscillator configured to output pulsed laser light, a coherence reduction optical system configured to reduce coherence of the pulsed laser light from the master oscillator, and a controller configured to control the coherence reduction optical system so that a speckle of the pulsed laser light varies.

Claims

1. A laser system, comprising:

a master oscillator configured to output pulsed laser light;

a coherence reduction optical system configured to reduce coherence of the pulsed laser light from the master oscillator, the coherence reduction optical system having a phase modulator which includes cells arranged with different thicknesses; and

a controller configured to control the coherence reduction optical system so that a speckle of the pulsed laser light varies.

2. The laser system according to claim 1, wherein the controller is configured to control the coherence reduction optical system so that the speckle varies for each laser pulse of the pulsed laser light.

3. The laser system according to claim 1, wherein the coherence reduction optical system further includes a rotation mechanism configured to rotate the phase modulator.

4. The laser system according to claim 1, wherein the coherence reduction optical system further includes:

a transparent wedge substrate having an output surface tilted with respect to an input surface on which the pulsed laser light is incident; and

a rotation mechanism configured to rotate the wedge substrate.

5. The laser system according to claim 1, wherein the coherence reduction optical system further includes:

a mirror configured to reflect the pulsed laser light; and

a tilt stage configured to change tilt of the minor with respect to an incident axis of the pulsed laser light.

6. The laser system according to claim 1, wherein the coherence reduction optical system further includes:

a transparent plane parallel plate having an input surface and an output surface of the pulsed laser light that are parallel to each other; and

a tilt stage configured to change tilt of the plane parallel plate with respect to an incident axis of the pulsed laser light.

7. The laser system according to claim 1, wherein the coherence reduction optical system further includes:

a mirror configured to reflect the pulsed laser light; and

a shifting mechanism configured to change a distance between the mirror and the random phase plate.

8. The laser system according to claim 1, further comprising an amplifying apparatus configured to amplify pulsed laser light having passed through the coherence reduction optical system.

13. The laser system according to claim 1, wherein the phase modulator is a plate having the cells arranged two-dimensionally with different thicknesses.

14. The laser system according to claim 1, wherein the pulsed laser light from the master oscillator passes through the cells of the phase modulator.

9. A laser light generation method comprising:

outputting pulsed laser light from a master oscillator;

reducing coherence of the pulsed laser light outputted from the master oscillator by a coherence reduction optical system having a phase modulator which includes cells arranged with different thicknesses; and

controlling the coherence reduction optical system so that a speckle of the pulsed laser light varies.

10. The method according to claim 9, wherein the coherence reduction optical system is controlled so that the speckle varies for each laser pulse of the pulsed laser light.

11. The method according to claim 10, wherein the coherence reduction optical system is controlled so that the speckle varies by a given amount for each laser pulse of the pulsed laser light.

12. The method according to claim 10, wherein the coherence reduction optical system is controlled so that the speckle varies in a random manner for each laser pulse of the pulsed laser light.

15. The method according to claim 9, wherein the pulsed laser light outputted from the master oscillator passes through the cells of the phase modulator.