Polarization state converting element

Patent metadata

Field	Value
Publication number	US-10031270-B2
Application number	US-201515303410-A
Country	US
Kind code	B2
Filing date	Apr 24, 2015
Priority date	Apr 30, 2014
Publication date	Jul 24, 2018
Grant date	Jul 24, 2018

Abstract

Provided is a polarization state converting element including a plurality of waveplates, and a rotation mechanism that rotates the respective waveplates independently of one another around an optical axis. The waveplates are each configured by a substrate made of a material having no optical rotatory property but having birefringence, or are each made of a material having neither optical rotatory property nor birefringence, but having transparency, a function of phase delay depending on polarization being applied on a surface of each waveplate.

First claim

The invention claimed is:

1. A polarization state converting element for a laser machining apparatus, comprising:
two ⅛ waveplates; and
a rotation mechanism that rotates the respective waveplates independently to one another around an optical axis,
wherein the waveplates are each made of a material having neither optical rotatory property nor birefringence, but having transparency, a function of phase delay depending on polarization being applied on a surface of each waveplate, and
wherein the polarization state converting element does not include any other waveplates in addition to the two ⅛ waveplates.

2. The polarization state converting element for a laser machining apparatus according to claim 1 , wherein a total of phase shifts of the two ⅛ waveplates is 85° or more, and 360° or less.

3. The polarization state converting element for a laser machining apparatus according to claim 2 , wherein the total of phase shifts of the plurality of the two ⅛ waveplates is 90° or more, and the maximum value of the difference of the phase shifts is 3° or less.

4. The polarization state converting element for a laser machining apparatus according to claim 1 , wherein a maximum value of a difference of the phase shifts of the the two ⅛ waveplates is 0° or more, and 5° or less.

5. The polarization state converting element for a laser machining apparatus according to claim 4 , wherein the total of phase shifts of the two ⅛ waveplates is 90° or more, and the maximum value of the difference of the phase shifts is 3° or less.

6. A method for controlling a polarization state of a laser machining apparatus comprising the polarization state converting element for the laser machining apparatus according to claim 1 , the method comprising the steps of:
disposing the polarization state converting element in an optical path of a laser beam emitted from a laser oscillator, the polarization state converting element converting the polarization state of the laser beam from linearly polarized light to circularly polarized light; and
rotating the respective two ⅛ waveplates in the polarization state converting element independently to one another around an optical axis of the laser beam to change respective azimuth angles so that an amplitude ellipticity of the laser beam is 1.05 or less in a state irradiated to a workpiece.

Assignees

• Sumitomo Electric Industries
• Sumitomo Electric Hardmetal Corp

Inventors

• Kameda Shinji
• Yajima Kunimitsu
• Iwamoto Hiromi

Classifications

• G02B5/3083 Primary

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• G11B7/08

  Disposition or mounting of heads or light sources relatively to record carriers · CPC title

• B23K26/064

  by means of optical elements, e.g. lenses, mirrors or prisms · CPC title

• B23K26/00

  Working by laser beam, e.g. welding, cutting or boring · CPC title

• G02B27/09

  Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for {(adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005)} · CPC title