JPH06142953A - Laser beam machine - Google Patents

Abstract

PURPOSE:To miniaturize the laser beam machine having high accuracy which is not affected by a temperature drift of an optical scanner, and to reduce its cost. CONSTITUTION:Quadrisplit type photodiodes 14, 15 for detecting a position are irradiated with a laser light of a position detection laser oscillator 3 through optical scanners 9, 10. As for a fitting position of these photodiodes 14, 15, an output of the photodiode 14 by a position detection laser light at the time when the optical scanners 9, 10 are set at an preset original position is made a deviation amount from the original position. Also, an output of the photodiode 15 by the laser light at the time when the optical scanners 9, 10 are set at a preset gain detecting position is made a deviation amount from the normal gain. In accordance with these deviation amounts, a movement of the scanner is corrected.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus having a processing position detection / correction function.

[0002]

2. Description of the Related Art FIG. 2 shows a schematic configuration diagram of a conventional laser processing apparatus having such a processing position detecting and correcting function.

A plurality of reference marks 44 provided in advance in the vicinity of the workpiece 44 are imaged by the CCD camera 1 and displayed on the monitor 41 via the image recognition section 40. Then, the image recognition unit 40 recognizes the position of the center of gravity between the plurality of reference marks 44, that is, the center position of the processed portion 44 from this image.

Based on the recognized data, the computer 42 calculates the correction amount of the central position of the scanning range of the processing laser light by the optical scanners 9 and 10 with scanner mirrors. The control unit 43 controls the scanning of the optical scanners 9 and 10 according to the correction result.

That is, the difference between the center position of the scanning range of the laser beam and the center position between the reference marks (the center position of the workpiece) resulting from image recognition is calculated by a computer,
By feeding back the difference to the command coordinate value and correcting it, the actual position of the workpiece center position is consistent with the optical scanner origin position and the actual moving amount with respect to the moving coordinate command value.

Reference numerals 5 and 12 are total reflection mirrors, and 11 is f _θ.
Reference numeral 16 is a lens, 16 is an assist gas nozzle for blowing away unnecessary substances during processing, and 17 is a transparent window.

In such a conventional laser processing apparatus, in order to perform high-resolution and high-accuracy image recognition, a reference mark must be newly provided in the vicinity of the workpiece, and the reference mark must be removed. A high-magnification observing optical system and an image recognition device are required for this purpose, which is a factor that hinders downsizing and cost reduction.

Further, in terms of processing capability, it is necessary to take time for the assist gas nozzle attached to the XY stage required for recognition, calculation, correction, cutting, and processing to retreat, which greatly affects a series of processing operations. Has the disadvantage of spending a lot of time.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser processing apparatus capable of removing the influence of temperature drift of an optical scanner with a simple structure and at high speed.

[0010]

According to the present invention, a laser oscillator for emitting a laser beam for processing and a laser oscillator for emitting a laser beam for position detection, a scanner optical section for scanning these laser beams, and the position detecting section through the scanner optical section in the previous period. A laser processing apparatus including: a displacement detection unit that detects a displacement state of a laser beam from a reference position; and a control unit that controls the scanner optical unit according to a displacement amount by the displacement detection unit. To be

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

First, the structure of the optical system used in the embodiment of the present invention will be described with reference to FIG. The semiconductor laser light 3-a output from the position detecting semiconductor laser oscillator 3 becomes parallel light by the collimator 4, is reflected by the total reflection mirror 5, and becomes coaxial with the processing YAG laser light 6.

The YAG laser light 6 is collimated by the collimator 7 and is reflected by the total reflection mirror 8. The X-axis optical scanner 9 with a mirror and the Y-axis optical scanner 1 are provided.
0 and scan.

While being focused by the f _θ lens 11, the YAG laser beam is totally reflected back by the YAG laser beam total reflection mirror 12, passes through the nozzle window glass 17 and the assist gas nozzle 16, and is condensed by the processing section 19. . The assist gas nozzle 16 and the window glass 17 together with the XY stage 18
And the YAG laser light 6 are moved in synchronism with, to blow away unnecessary objects during processing. High-pressure gas is flowing into the assist gas nozzle 16.

On the other hand, the semiconductor laser light 3-a transmitted through the YAG laser light total reflection mirror 12 is returned upward by the semiconductor laser light total reflection mirror 13 and is incident on the position detecting split type photodiodes 14 and 15. . When the optical scanners 9 and 10 are moved from the split type photodiodes 14 and 15 to a preset origin,
The amount of displacement from the set position when moving to a preset gain detection point is output as a signal.

FIG. 1 is a block diagram of a control system according to an embodiment of the present invention. The computer 20 outputs a position detection / correction start signal to the semiconductor laser drive unit 22, and the semiconductor laser 3 oscillates with a signal from the drive unit 22.

Photodiodes (for origin detection and gain detection) 14 and 15 receive this laser light and amplify / calculate / A / D as a signal the amount of displacement from a preset position.
Output to the conversion unit 24. This calculation result is the computer 2
0 is input, the amount of position variation is calculated, a correction value is calculated, and a signal after correction is output to the optical scanner control unit 29.

The optical scanners 9 and 10 include a control unit 2
In accordance with the corrected drive signal from 9, the laser beam output from the processing YAG laser oscillator 21 is scanned in X and Y directions.
An assist gas nozzle is attached to the XY stage 18 and moves in synchronization with the YAG laser light. This movement amount is a value calculated by the computer 20 and is used by the drive unit 27.
Is determined by the signal from.

FIG. 3 shows the split type photodiodes 14 and 15 used in the present invention and the displacement signal amplifying / calculating / A / D converter 24.
Details of the relationship with This split photodiode is divided into four by an X direction area gap 34a and a Y direction area division gap 34b. When the four-divided areas are A, B, C, and D areas, respectively, the semiconductor laser light 33
When b is condensed only in the A region, the output from this photodiode is a signal output only from the A region.

When the semiconductor laser 33a is uniformly focused in the A, B, C and D areas, the output from the photodiode is evenly output from the A, B, C and D areas.

The signals output from the A, B, C and D regions of the photodiode are amplified by amplifiers 40, 41, 42 and 43.
Respectively, and the signals output from the B area and the C area are added to each other to form an output signal in the negative (-) X direction of the photodiode, and the amplifier 46 in the X direction adds the output in the A area and the D area, An output signal in the X direction is obtained by obtaining the difference from the minus (-) X direction addition output.

On the other hand, the minus (-) Y direction amplifier 45
Then, the addition output of the C area and the D area is obtained, and the Y direction amplifier 47
The output signal in the Y direction is obtained by calculating the difference between the added output in the A and B areas and the added output in the negative (-) Y direction.

The X-direction and Y-direction outputs are digitally converted by the A / D converter 48 and a signal is sent to the computer 20. Since this signal represents the focus position of the semiconductor laser on the split type photodiode, the computer 20 can immediately read the position data.

The semiconductor laser beam focusing position is set to the center position (0, 0) of the split type photodiode, that is, the output signals by the semiconductor laser focusing from the regions A, B, C and D of the split type photodiode are made uniform. The optical scanner can have an absolute origin position by presetting to the position.

When the optical scanner is moved to the absolute origin position, it cannot always be moved to the absolute origin position due to temperature drift of the optical scanner and the control unit. Since the position variation amount at this time is expressed as a displacement amount from the split type photodiode center, it is possible to always move to the absolute origin position by giving the movement coordinate command value an offset corresponding to the variation amount.

With respect to the movement coordinate command value of the optical scanner, the actual movement amount often does not always match the movement coordinate command value due to temperature drift or the like. Even for such gain fluctuations, the split photodiode is installed at the maximum scan area coordinate value of the optical scanner as described above, so that the gain fluctuation magnification is calculated and corrected, and the moving coordinates are constantly adjusted. It is possible to move to a position that matches the command value.

The center of the split photodiode 15 for gain variation detection is set in advance at the moving coordinate command value X, and the output from the split photodiode 15 is actually obtained for the moving coordinate command value. If the amount of movement is X + α, X / (X + α) × 100
The correction variation rate of the gain can be obtained by (%).

If the optical scanner is moved by a value obtained by multiplying the correction variation rate calculated above by all the coordinate command values as a coefficient, the optical scanner can always be moved by an amount that matches the moving coordinate command value.

The circuit system requires another set of the same arithmetic circuit as that shown in FIG. The condition is that the absolute origin position is corrected before the gain variation is detected.

[0030]

According to the present invention, the movement position of the position detecting laser light passing through the scanner optical system can be corrected very easily and at high speed. Therefore, the adverse effect of temperature drift of the scanner optical system can be suppressed at high speed. And there is an effect that it can be eliminated at low cost.

[Brief description of drawings]

FIG. 1 is a system block diagram of an embodiment of the present invention.

FIG. 2 is a schematic diagram of an optical system used in an example of the present invention.

FIG. 3 is a diagram showing a relationship between a position detection photodiode and a position detection signal processing system in the embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a conventional laser processing apparatus.

[Explanation of symbols]

3 Position Detection Semiconductor Laser Oscillator 6 Processing YAG Laser Light 9, 10 Optical Scanner with Mirror 14 Origin Position Detection Correction Split Photodiode 15 Gain Variation Magnification Detection Correction Split Photodiode 20 Computer 21 Processing YAG Laser Oscillator 24 Displacement signal amplification / calculation / A / D converter

Claims (3)

[Claims] 1. A laser oscillator that emits laser beams for processing and position detection respectively, a scanner optical unit that scans these laser beams, and a reference position of the laser beam for position detection that has passed through the scanner optical unit in the previous period. A laser processing apparatus comprising: a displacement detecting section for detecting the displacement state of the scanner and a control section for controlling the scanner optical section according to the displacement amount by the displacement detecting section. 2. The laser processing apparatus according to claim 1, wherein the reference position is a position of the position detecting laser beam when the scanner optical unit is at a preset origin position. 3. The laser processing apparatus according to claim 1, wherein the reference position is a position of the position detection laser beam when the scanner optical unit is at a preset gain detection position.