HK1077250B - Laser machining apparatus - Google Patents

Description

Laser processing apparatus

Technical Field

The present invention relates to a laser processing apparatus which adjusts a laser beam emitted from a laser oscillator in X and Y directions of a workpiece by an optical axis adjusting unit including two mirrors.

Background

Fig. 4 is a schematic structural view of a conventional laser processing apparatus, and fig. 5 is a schematic view of a conventional optical system.

The conventional laser processing apparatus 60 includes: a laser oscillator 1, a total reflection mirror 3, an external optical system 4, a total reflection mirror 5, an optical axis adjusting unit 6, a condenser lens (f θ lens) 8, and a stage 10. A laser beam 2 emitted from the center of an opening (light emitting section) 1a of a laser oscillator 1 enters an external optical system 4 composed of a lens and other components through a total reflection mirror 3, and is irradiated onto a workpiece 9 fixed on a table 10 through an optical axis adjusting unit 6 and a condenser lens (f θ lens) 8.

The optical axis adjusting unit 6 includes total reflection mirrors 6a and 6b whose rotation axes intersect with each other, and scanning motors 6c and 6d for rotating the total reflection mirrors 6a and 6 b. The table 10 is provided movably in the X and Y directions (directions transverse and perpendicular to the drawing plane). Therefore, by rotating the total reflection mirrors 6a and 6b, the laser beam 2 can be adjusted to the target position of the workpiece 9. Note that the optical axis adjusting means 6 is provided optically for reducing the image formed after the external optical system 4 at the processing point by the condenser lens 8 and forming an image of the image.

In addition, in one case, the laser beam 2 does not pass through the deflection point of the condenser lens 8 depending on the rotation angle of the total reflection mirror 6 a. Therefore, japanese laid-open patent 1993-228673 has proposed a method in which a total reflection mirror is provided between the laser oscillator 1 and the total reflection mirror 6a to adjust the incident position of the laser beam 2 on the total reflection mirror 6a, thereby causing the laser beam 2 to pass through the polarizing point of the condenser mirror 8 by moving the total reflection mirror while keeping the angle of the total reflection mirror with the incident light constant.

Fig. 6 is a schematic plan view showing the opening 1a of the laser oscillator 1. An optical system including lenses and mirrors in the laser oscillator 1 shapes and controls the divergence angle of the laser beam 2 formed in the oscillation source within the laser oscillator 1 so that the optical axis of the laser beam coincides with the center Q of the opening 1a of the laser oscillator 1 and is perpendicular to the opening 1a parallel to the drawing plane as shown in fig. 6. However, since the temperature of the lens and the mirror in the laser oscillator 1 rises, causing thermal deformation when the laser beam passes through them, there is a case where the optical axis position in the opening 1a is moved to a point deviated from the center Q, such as Q1, or the optical axis is not perpendicular to the opening 1 a. Further, when the oscillation frequency or the output of the laser oscillator 1 is changed, the optical axis position in the opening 1a may also be deviated from the center Q, or the optical axis may not be perpendicular to the opening 1 a. The deviation from the optical axis center Q, the deviation direction, and the output angle thereof at the opening 1a also vary depending on the conditions of use, and are not uniform.

The above-described conventional laser processing apparatus is configured such that the laser beam passes through the deflection point of the condenser lens 8 via the total reflection mirror, thereby allowing high-precision processing to be performed as long as the optical axis of the laser beam incident on the total reflection mirror is not changed. However, when the optical axis of the laser beam deviates or the output angle thereof is changed, the accuracy of adjusting the laser beam 2 to the target position is lowered, and therefore the accuracy of the processing position is lowered. Moreover, the image formed after the external optical system 4 is distorted or has a defect, thereby lowering the forming accuracy of the processing point.

It is therefore an object of the present invention to provide a laser processing apparatus which solves the above-described problems by adjusting the optical axis of a laser beam with a predetermined optical axis.

Disclosure of Invention

According to a first aspect of the present invention, a laser processing apparatus includes an optical axis adjusting unit provided on a predetermined optical axis of a laser beam output from a laser oscillator to adjust the laser beam output from the laser oscillator onto a workpiece, the apparatus further including: an optical axis deflecting device provided between the laser oscillator and the optical axis adjusting unit, for arbitrarily deflecting the optical axis of the laser beam; and an optical axis position detecting device disposed between the optical axis adjusting unit and the optical axis deflecting device, for detecting an optical axis position of the laser beam, wherein the optical axis deflecting device is composed of two mirrors rotatable around an axis thereof; axes of the mirrors are respectively disposed perpendicular to a plane including the predetermined optical axis incident to and reflected from the mirror, and axes of the two mirrors intersect each other, and the axes of the mirrors are movable in a direction of the predetermined optical axis incident to or reflected from the mirror; the optical axis deflecting means adjusts the optical axis of the laser beam incident on the optical axis adjusting unit using the predetermined optical axis according to the result detected by the optical axis position detecting means; and moving an axis of the mirror in a direction of the predetermined optical axis incident to or reflected from the mirror to align the optical axis of the laser beam output from the laser oscillator with the predetermined optical axis when the optical axis of the laser beam output from the laser oscillator is deviated in parallel with the predetermined optical axis.

It is particularly preferable that the optical axis position detection means is provided so that it can detect the optical axis of the laser beam at two different points. According to the present invention described above, since the optical axis of the laser beam incident on the optical axis adjusting unit is always fixed even when the optical axis of the laser beam is deviated or inclined due to the processing conditions, which may vary corresponding to the elapsed processing time, the material quality of the workpiece, or the size of the drilled hole, the forming accuracy of the processed part and the uniform processing quality at the processing position can be obtained. Other objects and advantages of the present invention will become more apparent by a thorough understanding and detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram illustrating an optical system of the present invention;

fig. 2A and 2B are operation diagrams illustrating the mirror, wherein fig. 2A shows a case where the mirror is moved in the Z direction, and fig. 2B shows a case where the mirror is rotated in the u' direction;

FIG. 3 is a diagram illustrating the operation of a photon detector;

fig. 4 is a schematic view showing the structure of a conventional laser processing apparatus;

fig. 5 is a schematic view showing a conventional optical system; and

fig. 6 is a schematic plan view showing a light emitting portion of the laser oscillator.

Detailed Description

Preferred embodiments of the present invention will be described below with reference to fig. 1 to 3. Fig. 1 is a schematic diagram illustrating an optical system of the present invention. Fig. 2A and 2B are diagrams illustrating the operation of the mirror 12, wherein fig. 2A shows a case where the mirror 12 is moved in the Z direction, fig. 2B shows a case where the mirror 12 is rotated in the u' direction, and fig. 3 is a diagram illustrating the operation of the photo detector. Note that portions which are the same as or have the same functions as those in fig. 4 are denoted by the same reference numerals, and a description thereof will not be repeated.

The mirror (optical axis deflecting means) 12 has an axis 11 perpendicular to the incident direction and the reflection direction of the laser beam (i.e., in the direction perpendicular to the plane of the drawing), can rotate about the axis 11 in the direction of the arrow u-u ', and can be moved in the direction of the arrow z-z' perpendicular to the base optical axis O, i.e., in the vertical direction in the drawing (or in the lateral direction) by a moving unit, not shown. That is, the axis 11 of the mirror 12 is set to be perpendicular to a plane including the base optical axis O incident to or reflected from the mirror 12, and is movable in the direction of the base optical axis O reflected by the mirror 12 (or incident to the mirror 12). Note that the base optical axis O is the central axis of the laser beam output perpendicularly from the center Q of the opening 1a of the laser oscillator 1. And the reference angle of the mirror 12 to the base optical axis O is 45 °. Also, the axis 11 of the mirror 12 is disposed so as to intersect with an axis 21 of a mirror 20 described later.

Thus, by rotating the mirror 12 in the direction of the arrow u-u 'and moving the mirror in the Z-axis, i.e., in the direction of the arrow Z-Z', the optical axis of the laser beam 2 can be aligned with the base optical axis O on one of the X and Y axes on the surface of the workpiece 9.

The total reflection mirror 13 deflects the base optical axis O deflected by the reflection mirror 12 toward the back of the drawing plane in the direction perpendicular to the drawing plane.

The mirror (optical axis deflecting means) 20 has an axis 21 perpendicular to the incident direction and the reflection direction of the laser beam deflected by the total reflection mirror 13, i.e., in the vertical direction parallel to the plane of the drawing, and is rotatable about the axis 21 in the direction of the arrow v-v' and is also movable in the direction perpendicular to the plane of the drawing (or in the vertical direction in the drawing) by a moving unit, not shown. That is, the axis 21 of the mirror 20 is set to be perpendicular to a plane including the base optical axis O incident to or reflected by the mirror 20, and is movable in the direction of the base optical axis O reflected by the mirror 20 (or incident to the mirror 20). Note that the mutual relationship between the mirror 20 and the shaft 21 as viewed from the a direction in the drawing is the same as the relationship between the mirror 12 and the shaft 11, and the reference angle between the mirror 20 and the base optical axis O is also 45 °. And the axis 21 of the mirror 20 is arranged to intersect the axis 11 of the above-mentioned mirror 12.

The optical axis position detecting means is composed of first and second beam splitters 14 and 15 and photon detectors 16 and 17. The first and second beam splitters 14 and 15 are disposed at an inclination angle of 45 ° to the base optical axis O, and reflect 1% of the incident laser beam 2 as the beams to be detected 14S and 15S, while transmitting the other portions of the beams. Photon detectors 16 and 17 are disposed on the reflective sides of beam splitters 14 and 15. The photon detectors 16, 17 are provided with a plurality of small light receiving elements on the surfaces thereof, which are in a direction perpendicular to the plane of the beams to be detected 14S and 15S, with the centers to be detected being set on the extension line of the base optical axis O (when the laser beam is aligned with the base optical axis O).

Note that the external optical system 4 is disposed such that its axis is coaxial with the base optical axis O, and the total reflection mirror 6a of the optical axis adjustment unit 6 is disposed such that its rotation axis is perpendicular to the base optical axis O.

The operation of the present invention is explained below.

There are cases where the optical axes of the three laser beams 2 are misaligned from the base optical axis O, that is: the optical axis deviates from the basic optical axis O in parallel; the optical axis is obliquely deviated from the base optical axis O; and the optical axis is deviated in parallel and deviated obliquely from the base optical axis O.

The operation of the apparatus for these three cases is explained in turn below.

In the first case: the optical axis of the laser beam 2 is deviated in parallel from the base optical axis O in the Z-axis direction:

when the laser beam 2 is deviated in parallel to a position indicated by a two-dot chain line shown in fig. 2A, for example, the laser beam 2 is incident on the reflecting mirror 12 at point M1. In this case, the optical axis of the laser beam 2 can be aligned with the base optical axis O by moving the mirror 12 in the arrow Z direction to the position indicated by the dotted line in the figure.

In the second case: the optical axis of the laser beam 2 is inclined at an angle α to the base optical axis O:

when the laser beam 2 is tilted by an angle α to a position indicated by, for example, a two-dot chain line in fig. 2B, the laser beam 2 enters the reflecting mirror 12 at point M2. In this case, by tilting the mirror 12 by an angle α to a position indicated by a two-dot chain line in the drawing, the optical axis can be adjusted to be parallel to the base optical axis O as shown by the laser beam 2'. Then, as explained in the first case, by moving the mirror 12 upward in the drawing, i.e., in the arrow Z direction, the optical axis of the laser beam 2 can be aligned with the base optical axis O.

In the third case: the optical axis of the laser beam 2 is deviated in parallel and obliquely from the base optical axis O:

since this case is a combination of the above-described first case and second case, by changing the angle of the mirror 12 and moving the position of the mirror 12, the optical axis of the laser beam 2 can be aligned with the base optical axis O.

Due to the reflection of the optical axis by the mirror 13, the optical axis of the laser beam 2 can be aligned with the base optical axis O in the other of the X and Y axes on the surface of the workpiece 9 by using the base optical axis O from the laser oscillator 1 similarly to the mirror 12 by rotating the mirror 20 in the arrow v-v' direction and moving the mirror in the direction perpendicular to the drawing plane.

Note that the angle and distance by which the mirrors 12 and 20 are to be moved can be obtained by calculating the deviation of the centers of the beams to be detected 14S and 15S from the centers of the photon detectors 16 and 17.

The necessity of providing two photon detectors is now explained.

In general, photon detectors 16 and 17 are unable to discern the angle of incidence of an incident beam. Therefore, it may happen that the beam to be detected 14S separated from the laser beam is obliquely deviated from the base optical axis O and enters the photon detector 16 at the center thereof, for example, the optical axis of the beam to be detected 14S as shown in fig. 3. However, as shown, the optical axis of the beam to be detected 15S is offset from the center of the photon detector 17.

That is, when the rotation angles and positions of the mirrors 12 and 20 are set so that the optical axes of the light beams to be detected 14S and 15S enter the centers of the photon detectors 16 and 17, respectively, then the optical axis of the laser beam 2 coincides with the base optical axis O.

Note that when the optical axis of the laser beam 2 coincides with the base optical axis O, the optical axes of the beams to be detected 14S and 15S enter the centers of the photon detectors 16 and 17, respectively. Thus, there would be no need to move mirrors 12 and 20.

When two beam splitters and two photon detectors have been provided in the present embodiment, they can be used by moving them in the direction of the base optical axis O by means of one moving means, and set to detect the optical axes of the laser beams at two points of the beam splitters 14 and 15 in fig. 1.

Further, although the mirrors 12 and 20 are provided so as to be rotatable about their rotational axes in the present embodiment, they may be fixed when the inclination of the laser beam 2 to the base optical axis O is very small. In this case, each beam splitter and photon detector may be utilized and fixed.

Although the present embodiment has been described by exemplifying the laser processing apparatus 50 for processing a workpiece in a plane, the present invention is applicable not only to this example but also to a laser processing apparatus that processes, for example, a solid workpiece.

It will be apparent to those skilled in the art that many changes may be made in the details of the preferred embodiments of the invention described above. Accordingly, the scope of the invention is to be defined by the appended claims.

Claims (3)

1. A laser processing apparatus includes an optical axis adjusting unit provided on a predetermined optical axis of a laser beam output from a laser oscillator for adjusting the laser beam output from the laser oscillator onto a workpiece,

the laser processing apparatus further comprises the following means:

an optical axis deflecting device provided between the laser oscillator and the optical axis adjusting unit, for arbitrarily deflecting the optical axis of the laser beam; and

an optical axis position detecting device provided between the optical axis adjusting unit and the optical axis deflecting device, for detecting an optical axis position of the laser beam,

the optical axis deflection device consists of two reflecting mirrors capable of rotating around the axes thereof;

axes of the mirrors are respectively disposed perpendicular to a plane including the predetermined optical axis incident to and reflected from the mirror, and axes of the two mirrors intersect each other, and the axes of the mirrors are movable in a direction of the predetermined optical axis incident to or reflected from the mirror; and

the optical axis deflecting means aligns the optical axis of the laser beam incident on the optical axis adjusting unit with a predetermined optical axis by moving each of the mirrors in a direction of the predetermined optical axis of the laser light reflected from the mirror and/or rotating each of the mirrors around each axis perpendicular to the optical axis of the laser light incident on and reflected from the mirror, according to a result detected by the optical axis position detecting means.

2. The laser processing apparatus according to claim 1, wherein the optical axis position detection means is provided on the predetermined optical axis so that the optical axis of the laser beam can be detected at two different points.

3. The laser processing apparatus according to claim 2, wherein the optical axis position detecting means includes: a first beam splitter and a second beam splitter provided at the two different points where the predetermined optical axis passes, for splitting the laser beam; and two photon detectors for receiving the laser beams separated by the first beam splitter and the second beam splitter, respectively.