Light source apparatus and inspection apparatus

Patent metadata

Field	Value
Publication number	US-9696568-B2
Application number	US-201615153569-A
Country	US
Kind code	B2
Filing date	May 12, 2016
Priority date	May 13, 2015
Publication date	Jul 4, 2017
Grant date	Jul 4, 2017

Abstract

Provided are a light source apparatus and an inspection apparatus that can stably output a wavelength converted light beam. A light source apparatus includes a laser light source that generates a first fundamental light beam, at least one nonlinear optical crystal that generates a wavelength converted light beam using the fundamental light beam or a harmonic laser beam of the fundamental light beam as an incident light beam, a detector that detects the wavelength converted light beam, an acousto-optic modulator that is disposed in an optical path of the incident light beam in such a way that a zero-order light beam enters the nonlinear optical crystal, and a controller that controls an output intensity of the wavelength converted light beam according to a detection signal from the detector.

First claim

The invention claimed is:

1. A light source apparatus comprising:
a first laser light source that generates a first fundamental light beam;
a second laser light source that generates a second fundamental light beam, the second fundamental light beam having a wavelength different from that of the first fundamental light beam;
an at least one nonlinear optical crystal that generates a wavelength converted light beam by sum-frequency mixing, the sum frequency mixing using the first fundamental light beam and a harmonic light beam of the second fundamental light beam as incident light beams;
a detector that detects the wavelength converted light beam;
an acousto-optic modulator that is disposed in an optical path between the first laser light source and the nonlinear optical crystal or an optical path between the second laser light source and the nonlinear optical crystal, the acousto-optic modulator being disposed in such a way that a zero-order light beam enters the nonlinear optical crystal;
a coupling mirror that is disposed in an optical path between the acousto-optic modulator and the nonlinear optical crystal and is disposed in such a way that the harmonic laser beam of the second fundamental light beam will become coaxial with the first fundamental light beam; and
a controller configured to output a control signal that changes a diffraction efficiency of the acousto-optic modulator and to control an output intensity of the wavelength converted light beam according to a detection signal from the detector.

2. The light source apparatus according to claim 1 , wherein:
a wavelength of the first fundamental light beam is in a range of 1000 to 1200 nm,
an incident light beam with a wavelength in a range of 200 to 280 nm by fourth-order or fifth-order harmonic generation of the second fundamental light beam enters the nonlinear optical crystal, and
the acousto-optic modulator is disposed in an optical path of the first fundamental light beam.

3. The light source apparatus according to claim 1 , wherein:
a wavelength of the first fundamental light beam is in a range of 1000 to 1200 nm,
an incident light beam with a wavelength in a range of 200 to 280 nm by fourth-order or fifth-order harmonic generation of the second fundamental light beam enters the nonlinear optical crystal, and
the acousto-optic modulator is disposed in an optical path of the second fundamental light beam.

4. The light source apparatus according to claim 1 , wherein:
a wavelength of the first fundamental light beam is in a range of 1000 to 1200 nm,
an incident light beam with a wavelength in a range of 200 to 280 nm by fourth-order or fifth-order harmonic generation of the second fundamental light beam enters the nonlinear optical crystal, and
the acousto-optic modulator is disposed in an optical path of a second harmonic laser beam of the second fundamental light beam.

5. An inspection apparatus comprising:
the light source apparatus according to claim 1 ; and
an optical element configured to reduce coherence in an optical path of the wavelength converted light beam.

6. The inspection apparatus according to claim 5 , wherein the detector is configured to detect a wavelength converted light beam output that has passed through the optical element.

Assignees

• Lasertec Corp

Inventors

• Sakuma Jun

Classifications

• H01S3/0085

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

• G01N2201/06113

  Coherent sources; lasers · CPC title

• H01S3/0092

  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 title

• G02B27/141

  using dichroic mirrors · CPC title

• G01N21/636

  using an arrangement of pump beam and probe beam; using the measurement of optical non-linear properties; (non-linear optics per se G02F1/35) · CPC title