Laser processing apparatus and optical adjustment method

Patent metadata

Field	Value
Publication number	US-11648624-B2
Application number	US-202016941446-A
Country	US
Kind code	B2
Filing date	Jul 28, 2020
Priority date	Aug 29, 2019
Publication date	May 16, 2023
Grant date	May 16, 2023

Abstract

A laser processing apparatus emits processing light, measurement light, processing guide light, and measurement guide light with which a surface of a workpiece is irradiated. Respective wavelengths of the processing guide light and the measurement guide light are set to wavelengths at which a deviation amount between an irradiation position of the processing guide light and an irradiation position of the measurement guide light due to a chromatic aberration of magnification of a lens, and a deviation amount between an irradiation position of the processing light and an irradiation position of the measurement light due to the chromatic aberration of magnification of the lens are equal to each other. Therefore, positioning of spot positions of a plurality of laser lights having different output differences can be realized with high accuracy and high speed.

First claim

What is claimed is:

1. A laser processing apparatus comprising:
a laser oscillator that emits a processing light with which a processing point of a surface of a workpiece is irradiated;
a measurement unit that emits a measurement light with which the processing point is irradiated, and detects the measurement light reflected from a bottom surface of a keyhole formed at the processing point, wherein a wavelength of the measurement light is different from a wavelength of the processing light;
a first mirror that combines the processing light and the measurement light;
a second mirror configured to change an angle of measurement light, wherein the second mirror is adjusted such that an irradiation position of the processing light and an irradiation position of the measurement light on the surface of the workpiece match with each other;
a lens that condenses the processing light and the measurement light on the processing point; and
a measurement processor that performs a predetermined measurement based on a signal from the measurement unit,
wherein for adjusting a deviation between an irradiation position of the processing light and an irradiation position of the measurement light on the surface of the workpiece, the laser oscillator emits a processing guide light with which the surface of the workpiece is irradiated and the measurement unit emits a measurement guide light with which the surface of the workpiece is irradiated, the processing guide light having a different wavelength from the processing light and the measurement guide light having a different wavelength from the measurement light,
wherein respective wavelengths of the processing guide light and the measurement guide light are set to wavelengths at which a deviation amount between an irradiation position of the processing guide light and an irradiation position of the measurement guide light due to a chromatic aberration of magnification of the lens, and a deviation amount between the irradiation position of the processing light and the irradiation position of the measurement light due to the chromatic aberration of magnification of the lens are equal to each other,
wherein the irradiation position of the processing guide light and the irradiation position of the measurement guide light match with each other by adjusting the angle of the measurement guide light using the second mirror and thereby the irradiation position of the processing light and the irradiation position of the measurement light match each other, and
wherein the respective wavelengths of the processing guide light and the measurement guide light are set by obtaining the deviation amount between the irradiation position of the processing light and the irradiation position of the measurement light when the processing light and the measurement light are respectively incident on the lens at a desired incident angle, obtaining a correspondence relationship between a candidate wavelength used for each of the processing guide light and the measurement guide light, and an irradiation position when a light having the respective one of the candidate wavelengths is incident on the lens at the desired incident angle, and obtaining a combination of the candidate wavelengths having a deviation within a target accuracy with respect to the deviation amount between the irradiation position of the processing light and the irradiation position of the measurement light.

2. The laser processing apparatus of claim 1 , wherein the first mirror is a dichroic mirror.

3. The laser processing apparatus of claim 1 , wherein the measurement unit is an optical interferometer that generates an optical interference intensity signal based on interference generated by an optical path difference between the measurement light reflected at the processing point and reference light.

4. The laser processing apparatus of claim 3 , wherein the measurement processor calculates a depth of a keyhole generated at the processing point based on the optical interference intensity signal.

5. The laser processing apparatus of claim 1 , further comprising:
a two-dimensional light receiving element that detects the irradiation positions of the processing guide light and the irradiation position of the measurement guide light.

6. The laser processing apparatus of claim 1 ,
wherein when a first deviation amount is the deviation amount between an irradiation position of the processing guide light and an irradiation position of the measurement guide light due to the chromatic aberration of magnification of the lens, and when a second deviation amount is the deviation amount between the irradiation position of the processing light and the irradiation position of the measurement light due to the chromatic aberration of magnification of the lens, and
the respective wavelengths of the processing guide light and the measurement guide light are set to wavelengths, by an optical simulation, such that the first deviation and the second deviation amount are in a range of ±0.010 mm to each other and that the wavelengths are in a range of 300 nm to 1100 nm.

7. A laser processing apparatus includes,
a laser oscillator that emits a processing light with which a processing point of a surface of a workpiece is irradiated,
a measurement unit that emits a measurement light with which the processing point is irradiated, and detects the measurement light reflected from a bottom surface of a keyhole formed at the processing point,
a first mirror that combines the processing light and the measurement light,
a second mirror configured to change an angle of measurement light, wherein the second mirror is adjusted such that an irradiation position of the processing light and an irradiation position of the measurement light on the surface of the workpiece match with each other,
a lens that condenses the processing light and the measurement light on the processing point and
a measurement processor that performs a predetermined measurement based on an optical interference intensity signal from the measurement unit,
wherein for adjusting a deviation between an irradiation position of the processing light and an irradiation position of the measurement light on the surface of the workpiece, the laser oscillator emits a processing guide light with which the surface of the workpiece is irradiated and the measurement unit emits a measurement guide light which the surface of the workpiece is irradiated, the processing guide light having a different wavelength from the processing light and the measurement guide light having a different wavelength from the measurement light, and
wherein respective wavelengths of the processing guide light and the measurement guide light are set to wavelengths at which a deviation amount between an irradiation position of the processing guide light and an irradiation position of the measurement guide light due to a chromatic aberration of magnification of the lens, and a deviation amount between the irradiation position of the processing light and the irradiation position of the measurement light due to the chromatic aberration of magnification of the lens are equal to each other, wherein
a wavelength of the processing light and a wavelength of the measurement light are different from each other,
the first mirror is a dichroic mirror,
the measurement unit is an optical interferometer that generates the optical interference intensity signal based on interference generated by an optical path difference between the measurement light reflected at the processing point and reference light,
wherein the irradiation position of the processing guide light and the irradiation position of the measurement guide light match with each other by adjusting the angle of the measurement guide light using the

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Yokoyama Jun
• Takechi Yohei

Classifications

• G02B19/0014

  at least one surface having optical power · CPC title

• B23K26/042 Primary

  Automatically aligning the laser beam · CPC title

• G01B2210/50

  Using chromatic effects to achieve wavelength-dependent depth resolution · CPC title

• B23K26/0665

  by beam condensation on the workpiece, e.g. for focusing · CPC title

• B23K26/382

  by boring · CPC title