US 2015/0092196 A1Published application

Optical measurement apparatus

AssigneeHitachi-LG Data Storage, Inc.

InventorKentaro OSAWA

Life of this patent

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Abstract

A clear image of a target to be measured is obtained by suppressing influence of a reflected beam from the surface of the target or a measurement target holding unit. A laser beam emitted from a light source is split into a signal beam, reference beam, and control beam. The signal beam is focused onto the target with an objective lens, so the target is irradiated with the signal beam. The amount of defocus of the control beam is controlled with a defocus control unit, and the phase of the control beam is controlled with a phase control unit. A signal beam reflected or scattered by the target is combined with the control beam to generate a controlled signal beam, and the controlled signal beam is combined with the reference beam. A plurality of interference beams with different phases are generated with interference optics, and phase diversity detection is performed.

Claims9

Dependent claims

An optical measurement apparatus comprising:

a light source configured to emit a laser beam;
an optical splitter configured to split the laser beam into a signal beam, a reference beam, and a control beam;
an objective lens configured to focus the signal beam onto a target to be measured and irradiate the target to be measured with the signal beam;
a focus position moving unit configured to move a focus position of the signal beam;
a defocus control unit configured to control an amount of defocus of the control beam;
a phase control unit configured to control a phase difference between the control beam and the signal beam;
a controlled signal beam generating unit configured to combine a signal beam reflected or scattered by the target to be measured with the control beam to generate a controlled signal beam;
interference optics configured to combine the controlled signal beam with the reference beam to generate a plurality of interference beams with different phases;
and
a photodetector configured to detect the interference beams.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/503,560Filed 1 Oct 2014
Priority: JP 2013-2069622 Oct 2013
Published: 2 Apr 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G01B 9/02091
Low-coherence interferometers: tomographic interferometers, e.g. based on optical coherence
A61B 5/0066
Arrangements for scanning: optical coherence imaging
G01B 9/02025
Characterised by the beam path configuration: interference between three or more discrete surfaces
G01B 9/02059
Passive reduction of errors: reducing effect of parasitic reflections, e.g. cyclic errors