# US 7,608,799 B2 · Solid-state laser processing apparatus and laser welding process

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 7,608,799 B2
- Document ID: US7608799B2
- Status: Granted
- Kind: B2
- Application number: 11/001,052
- Filed: 2004-12-02
- Published: 2005-06-09
- Granted: 2009-10-27
- Earliest claimed: 2003-12-05
- Assignees: Toyota Jidosha Kabushiki Kaisha; Mitsubishi Denki Kabushiki Kaisha
- Inventors: Hironari Mikata; Kazuhisa Mikame; Akio Sato; Kazuki Kuba; Shuichi Fujikawa; Toshiaki Watanabe
- Web page: https://patentgrep.com/patent/US7608799B2

## CPC

- B23K 26/073: Shaping the laser spot
- B23K 26/244: Overlap seam welding
- B23K 26/38: by boring or cutting
- G02B 6/4296: {coupling with sources of high radiant energy, e.g. high power lasers, high temperature light sources}
- 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

## Abstract

A solid-state laser processing apparatus includes a solid-state laser oscillator, a laser beam diameter controller, an optical fiber, and a processing head. The solid-state laser oscillator oscillates a laser beam. The laser beam diameter controller controls a beam diameter of the laser beam, and includes an aperture. The aperture controls a beam quality of the laser beam defined by M2 so as to fall in a range of 85≦M2≦105. The optical fiber guides the controlled laser beam therein. The processing head includes a transfer optical system, and irradiates the guided laser beam to a surface of a workpiece to be processed by way of the transfer optical system.

## Claims

### Claim 1

A laser welding process, comprising:
welding overlapped steel plates with a solid state laser processing apparatus, said apparatus comprising:
a solid-state laser oscillator for oscillating a laser beam, said oscillator comprising an exciter, a partial reflection mirror, first and second lenses, and an aperture having a controlled diameter for controlling a beam diameter of the laser beam;
an optical fiber for guiding the controlled laser beam; and
a processing head comprising a transfer optical system for focusing the guided laser beam, and for irradiating the guided laser beam to a surface of a workpiece to be processed;
the laser welding process comprising:
controlling the beam diameter by controlling the controlled diameter of the aperture such that a beam quality M2 of the laser falls in a range of 85≦M2≦105,
wherein the laser beam has a first incidence angle θ1 prior to entering the optical fiber, and a second incidence angle θ2 after exiting the optical fiber, wherein θ1=tan−1 (A/2L)=A/2L, and θ1≈θ2,
wherein the beam quality M2 is defined as M2=π×D×(θ2/1.5)/(2×λ), with D being the diameter of the optical fiber,
wherein λ is a wavelength of the laser beam,
wherein A is a diameter of the aperture,
wherein L is a distance from the aperture to the optical fiber,
wherein the transfer optical system comprises two spherical lenses, and
wherein the two spherical lenses are plane-convex lenses.

### Claim 2 (depends on 1)

The laser welding process set forth in claim 1, wherein the solid-state laser processing apparatus further comprises a laser medium composed of Nd:YAG.

### Claim 3 (depends on 1)

The laser welding process set forth in claim 1, wherein the first lens is a relay lens.

### Claim 4 (depends on 1)

The laser welding process set forth in claim 1, wherein the second lens is a condensing lens.