Light source apparatus and inspection apparatus

Patent metadata

Field	Value
Publication number	US-12308600-B2
Application number	US-202217664183-A
Country	US
Kind code	B2
Filing date	May 19, 2022
Priority date	May 21, 2021
Publication date	May 20, 2025
Grant date	May 20, 2025

Abstract

A decrease of an output of a wavelength converted light converted by a nonlinear optical crystal is suppressed. A light source apparatus according to the present disclosure includes a fundamental wave light source configured to generate a fundamental wave which is a continuous oscillation laser beam, an external cavity including a plurality of optical mirrors, a nonlinear optical crystal installed inside the external cavity and configured to generate a light with a wavelength shorter than that of the fundamental wave. The light source apparatus includes at least one phase modulator disposed between the fundamental wave light source and the external cavity and configured to modulate the fundamental wave by a modulation frequency of an integer multiple of a resonance frequency interval of the external cavity.

First claim

The invention claimed is:

1. A light source apparatus, comprising:
a fundamental wave light source configured to generate a fundamental wave, the fundamental wave being a continuous oscillation laser beam;
an external cavity including a plurality of optical mirrors;
a nonlinear optical crystal installed inside the external cavity and configured to generate a light with a wavelength shorter than that of the fundamental wave; and
at least one phase modulation means disposed between the fundamental wave light source and the external cavity and configured to modulate the fundamental wave by a modulation frequency of an integer multiple of a resonance frequency interval of the external cavity.

2. The light source apparatus according to claim 1 , wherein
the modulation frequency is equal to a longitudinal mode spacing of a laser generating the fundamental wave.

3. The light source apparatus according to claim 1 , wherein
a degree of modulation by the at least one phase modulation means is 0.5 radians or more.

4. The light source apparatus according to claim 1 , wherein
the light source apparatus includes a plurality of the at least one phase modulation means including modulation frequencies different from each other.

5. The light source apparatus according to claim 1 , further comprising:
error modulation means for generating an error signal in an FM sideband method disposed between the fundamental wave light source and the external cavity.

6. The light source apparatus according to claim 5 , further comprising:
a phase modulator serving as both the phase modulation means and the error modulation means.

7. The light source apparatus according to claim 1 , wherein
the nonlinear optical crystal is any one of a BBO crystal, a CLBO crystal, and an LBO crystal, and configured to generate the light with a wavelength of 400 nm or less.

8. An inspection apparatus comprising:
the light source apparatus according to claim 1 ,
wherein a sample to be inspected is irradiated with the light generated by the light source apparatus.

Assignees

• Lasertec Corp

Inventors

• Sakuma Jun
• Ando Akihiro

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H01S3/0085

  Modulating the output, i.e. the laser beam is modulated outside the laser cavity · CPC title

• H01S3/109

  Frequency multiplication, e.g. harmonic generation · CPC title

• H01S5/14

  External cavity lasers (H01S5/18 takes precedence; mode locking H01S5/065) · CPC title

• H01S3/108

  using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering {(mode locking using a non-linear element H01S3/1112)} · CPC title