Laser beam converter for converting a laser beam with a single high-order transverse mode into a laser beam with a desired intensity distribution and laser resonator for producing a laser beam with a single high-order transverse mode

• US 5,982,806 A
• Filed: 05/09/1997
• Issued: 11/09/1999
• Est. Priority Date: 05/10/1996
• Status: Expired due to Fees

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel Corporation
• Inventors: Minamida, Katsuhiro, Yamaguchi, Satoshi
• Primary Examiner(s): Davie, James W.
• Application Number:
  US08/854,096
• Time in Patent Office: 914 Days
• Field of Search: 372/98, 372/99, 372/102, 372/103, 372/19
• US Class Current: 372/103
• CPC Class Codes: H01S 2301/20 Lasers with a special output beam profile or cross-section, e.g. non-Gaussian
• CPC Class Codes: H01S 2301/203 with at least one hole in the intensity distribution, e.g. annular or doughnut mode
• CPC Class Codes: H01S 3/005 Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B

Abstract

In order to obtain a high-power laser beam with a high beam quality with use of a small-sized and low-cost apparatus, there has been disclosed a laser resonator which is constructed so as to produce a single high-order transverse mode laser beam, and a technique for converting the laser beam with a single high-order transverse mode into a laser beam with a high beam quality. The laser resonator is provided with a regulating plate of a high-order transverse mode which is constructed so as to produce a laser beam in a single high-order transverse mode. A phase adjusting plate inverts a phase for each region of the laser beam divided depending upon a lateral mode thereof to match the phase for each region of the laser beam, and subsequently, a traveling direction of the laser beam is changed for each position thereof by means of the first binary optics element, and further, the laser beam is converted into a parallel beam by means of the second binary optical element. The first binary optics element changes the traveling direction of the ray of the laser beam for each region thereof so that the laser beam has a desired intensity distribution on the second binary optics element.

Claims

1. A laser beam converter for converting a laser beam with a single high-order transverse mode into a laser beam with a predetermined distribution, comprising:

phase adjusting means for inverting a phase for each region divided depending upon a transverse mode of the laser beam so as to match the phase of each region of the laser beam;

first direction change means for changing a traveling direction of a ray of the laser beam with the phase matched by the phase adjusting means, for each position of the ray; and

second direction change means for changing the traveling direction of a ray of the laser beam exiting from the first direction change means for each position thereof so as to form a parallel laser beam,

the first direction change means changing a direction of the laser beam for each position thereof so that the laser beam becomes a predetermined intensity distribution at the second direction change means.

2. The laser beam converter according to claim 1, wherein the phase adjusting means and the first direction change means are integrated together, and are formed as an phase-adjusting/direction-change element.

3. The laser beam converter according to claim 1, wherein the phase adjusting means is a diffractive optical element.

4. The laser beam converter according to claim 3, wherein the phase adjusting means is a binary optics element.

5. The laser beam converter according to claim 1, wherein the first and the second direction change means are each a diffractive optical element.

6. The laser beam converter according to claim 5, wherein the first and the second direction change means are each a binary optics element.

7. The laser beam converter according to claim 2, wherein the phase-adjusting/direction-change element is a diffractive optical element.

8. The laser beam converter according to claim 7, wherein the phase-adjusting/direction-change element is a binary optics element.

9. The laser beam converter according to claim 2, wherein the second direction change means is a diffractive optical element.

10. The laser beam converter according to claim 9, wherein the second direction change means is a binary optics element.

11. The laser beam converter according to claim 1, wherein the laser beam converter further includes a first optical element for converging the laser beam exiting from the second direction change means, and a pinhole having a specified shape located on the laser beam converged position.

12. The laser beam converter according to claim 11, wherein the laser beam converter further includes a second optical element for converting the laser beam passing through the pinhole into a parallel laser beam.

13. The laser beam converter according to claim 1, wherein the laser beam converter includes an optical element for converging the laser beam exiting from the second direction change means onto a core end face of an optical fiber.

14. A laser beam converter for converting a laser beam with a single high-order transverse mode into a laser beam with an intensity of Gaussian distribution, comprising:

phase adjusting means for inverting a phase for each region divided depending upon a transverse mode of the laser beam so as to match the phase for each region;

a first optical element for converging the laser beam outputted from the phase adjusting means;

a pinhole with a specified shape located at the laser-beam converged position; and

a second optical element for converting the laser beam passing through the pinhole into a parallel laser beam.

15. An optical system for guiding a laser beam with a single high-order transverse mode onto an optical fiber, comprising:

phase adjusting means for inverting a phase for each region of the laser beam with a single high-order transverse mode divided depending upon a transverse mode of the laser beam so as to match the phase for each region of the laser beam with a single high-order transverse mode; and

an optical element for converging the laser beam exiting from the second a direction change means onto a core end face of an optical fiber.