# US 10,870,170 B2 · Beam homogenizer for surface modification

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- Number: US 10,870,170 B2
- Document ID: US10870170B2
- Status: Granted
- Kind: B2
- Application number: 16/074,765
- Filed: 2016-11-14
- Published: 2019-02-07
- Granted: 2020-12-22
- Earliest claimed: 2016-02-02
- Assignees: Handong Global University Foundation
- Applicants: Handong Global University Foundation
- Inventors: Tae Jun Yu; Kyung Hee Hong; Tae Shin Kim; Seung Jin Hwang; Yoong Wook Sin
- Web page: https://patentgrep.com/patent/US10870170B2

## CPC

- B23K 26/0648: {comprising lenses}
- B23K 26/0006: {taking account of the properties of the material involved (B23K26/32, B23K26/40 take precedence)}
- B23K 26/0652: {comprising prisms}
- B23K 26/067: Dividing the beam into multiple beams, e.g. multi-focusing
- B23K 26/1224: {in vacuum}
- B23K 26/142: for the removal of by-products
- B23K 26/146: the fluid stream containing a liquid
- B23K 26/1476: {Features inside the nozzle for feeding the fluid stream through the nozzle}
- B23K 26/70: Auxiliary operations or equipment
- B23K 26/702: {Auxiliary equipment}
- B23K 26/706: {Protective screens}
- G02B 27/0927: {Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat}
- 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)}
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

A beam homogenizer for surface modification comprises: a first lens array configured to split a laser beam, irradiated from a laser beam irradiation unit, into a plurality of beamlets; a second lens array configured to transmit the plurality of beamlets and comprising a plurality of lenslets corresponding to the first lens array; and a focusing lens configured to focus the plurality of beamlets, transmitted through the second lens array, onto a surface of a target. The beam homogenizer further comprises: a plasma generation-preventing unit disposed between the first and second lens arrays and configured to prevent plasma from being generated in the focal zone of the beamlets; or a damage-preventing unit disposed between the focusing lens and the target and configured to prevent the focusing lens from being damaged by energy generated when the plurality of beamlets is irradiated onto the target.

## Claims

### Claim 1

A beam homogenizer for surface modification, comprising:
a first lens array configured to split a laser beam, irradiated from a laser beam irradiation unit, into a plurality of beamlets, the first lens array comprising a plurality of lenslets configured to determine a shape of the laser beam;
a second lens array configured to transmit the plurality of beamlets split by the first lens array, the second lens array comprising a plurality of lenslets corresponding to the first lens array;
a focusing lens configured to focus the plurality of beamlets, transmitted through the second lens array, onto a surface of a target; and
a plasma generation-preventing unit disposed between the first lens array and the second lens array and configured to prevent plasma from being generated in a focal zone of the beamlets.

### Claim 2 (depends on 1)

The beam homogenizer of claim 1, wherein the plasma generation-preventing unit comprises a vacuum chamber disposed between the first lens array and the second lens array and having an internal space which is maintained in a vacuum atmosphere.

### Claim 3 (depends on 1)

The beam homogenizer of claim 1, wherein the plasma generation-preventing unit comprises a gas chamber formed to cover at least the focal zone of the beamlets and configured to receive a filling gas having a plasma generation threshold higher than that of air.

### Claim 4 (depends on 3)

The beam homogenizer of claim 3, wherein the gas chamber comprises first frames disposed on both sides of each of the first lens array and the second lens array and configured to cover a space between the first lens array and the second lens array.

### Claim 5 (depends on 4)

The beam homogenizer of claim 4, wherein the gas chamber further comprise second frames disposed in a direction parallel to the first lens array and the second lens array and configured to cover the space between the first lens array and the second lens array together with the first frames and also capable of transmitting the beam.

### Claim 6 (depends on 3)

The beam homogenizer of claim 3, wherein the filling gas comprises at least one of helium and neon.