JPH02104486A - Laser beam machine - Google Patents

Abstract

PURPOSE:To uniformly keep a high level working accuracy by detecting the deviation of an imaging position between a laser beam and a guide light and correcting the alignment according to the detected result. CONSTITUTION:After an X - Y stage is moved to bring a target under the objective lens, the target is irradiated with a suitable quantity of laser beams. Then, in a camera 15, a fluorescent image by the irradiation of the laser beam and the image of a guide light are observed simultaneously. Corrective signals 174 according to the quantity of deviation from a controller 173 is sent respectively to pulse motors 71, 72 to perform alignment of an aberration correcting lens system 6 to execute an adequate alignment. Thus, it is possible to eliminate the deviation of the imaging position between the laser beam and the guide light.

Description

[Detailed Description of the Invention] The present invention relates to a laser processing device, and more particularly to a mechanism for detecting and correcting a deviation in the imaging position between a laser beam and a guide light in a laser processing device using an imaging type optical system. Regarding.

Conventionally, in this type of laser processing equipment, thermal expansion is used to prevent misalignment between the laser beam and the guide light passing through the aberration correction lens system due to temperature changes or vibrations at the installation location. Making an optical surface plate using a material with a low ratio,
Countermeasures have been taken such as using a fixing method to reduce mechanical displacement of the aberration correction lens system in a plane perpendicular to the optical axis of the guide light. However, no mechanism was provided for detecting and correcting a shift in the imaging position between the laser beam and the guide light.

This is because the requirements for processing accuracy for this type of laser processing equipment were not so strict in the past, and when the deviation in the imaging position between the laser beam and the guide light became large enough, the aberration correction was done manually using the lens system. This is because the alignment was corrected. Moreover, in this case, the frequency of alignment correction was about once every few months, so it was not inconvenient in practical terms.

However, in recent years, requirements for processing accuracy for this type of laser processing equipment have become stricter, and it has become difficult to maintain equipment performance at a constant level by manually correcting the alignment of the aberration correction lens system. There were drawbacks.

Another drawback is that it is extremely difficult to maintain the aberration correcting lens system completely stably against changes in temperature, vibrations, etc. around the device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser processing apparatus that can accurately correct the deviation between a laser beam and a guide light on a processing surface.

The laser processing apparatus of the present invention includes: a laser oscillator that emits laser light other than visible light; an imaging lens that forms an image of the laser light emitted from the laser oscillator on a processing surface; a guide light irradiation means for irradiating a visible light guide light for confirming the irradiation position of the laser beam, the laser processing apparatus having a guide light irradiation means that irradiates a visible light guide light for confirming the irradiation position of the a detection means for detecting a shift between the laser light and the guide light when the target is irradiated with the laser light and the guide light; It is characterized by comprising an irradiation position correction means for matching the irradiation position of the guide light with the irradiation position of the guide light.

Shakuharayo Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram showing the configuration of a first embodiment of the laser processing apparatus according to the present invention. In FIG. 9, the laser processing apparatus according to the first embodiment of the present invention includes a laser oscillator 1 and a beam expander. 2, a rectangular slit 4, a dichroic mirror 5, an imaging lens 8, and an objective lens 9.

Further, the laser processing apparatus according to this embodiment has an alignment (^I
ignent) motor unit 7, an illumination light source 13,
It is configured to include an imaging lens 14, a camera 15, a monitor 16, and a controller 17.

In this configuration, after the beam diameter of the laser beam emitted from the laser oscillator 1 is expanded by the beam expander 2, only the center portion where the intensity distribution is flat passes through the rectangular slit 4 and is used for laser processing. The rectangular slit 4 is composed of two sets of knives having two axes orthogonal to each other, and the size of the opening thereof is variable.

After passing through the rectangular slit 4, the laser beam is reduced and transferred onto the workpiece 10 according to the image of the opening of the rectangular slit 4 using an imaging lens 8 and an objective lens 9, thereby performing laser processing. Note that focus adjustment is performed as shown by arrow W. At this time, the laser has a pulse width of 10 [n5cc]
pulsed laser (e.g., pulsed excitation of Nd:YA
Evaporation processing of metal thin films can be performed by using a G laser or its harmonics.

In addition, a high repetition rate laser (continuous excitation Q-switch Nd:
If the workpiece 10 is placed in a reactive gas atmosphere in a closed chamber using a YAG laser (harmonic wave) or a continuous wave laser, a thin film can be deposited by laser CVD.

The laser processing is performed using a camera 15 and a TV monitor 16. 13 is an illumination light source for observation, and 14 is an imaging lens for the camera 15.

However, as it is, the position and size of the laser beam irradiation are unknown, so the rectangular slit 4 is illuminated from behind with the slit illumination 3 and used as a guide light to indicate them.

This slit illumination 2 is performed using visible light, and if necessary, it is filtered to make it monochromatic. Further, since a laser in the ultraviolet or infrared wavelength range is used, an aberration correction lens system 6 is used to correct the chromatic aberration of the objective lens 9 and the imaging lens 8 to make the imaging planes equal.

Next, a method of adjusting the aberration correction lens system 6 in this actual glaze example will be explained using FIGS. 2, 4, and 5.

FIG. 4 is a block diagram showing the internal configuration of the controller 7 shown in FIG. 1, and parts equivalent to those in FIG. 1 are designated by the same reference numerals. In the figure, the controller 7 is the camera 15
an image memory (frame memory) 171 that temporarily stores the image signal 150 from the CPU 172, and a pulse motor controller that sends out a correction signal 174 for driving the pulse motors 71 and 72 provided in the aberration correction lens system 6. 173. In addition, 1
70 is a pass line.

In this embodiment, an aberration correction lens system 6 is provided in the guide light optical path 20 of the two optical paths separated by the dichroic mirror 5. Here, if the alignment of the guide light passing through the aberration correction lens system 6 becomes out of order due to factors such as temperature changes and vibrations around the device, the imaging positions of the laser light and the guide light on the workpiece 10 will be misaligned. Occur.

Further, in this embodiment, the camera 15 and the target 11 are used to detect the positional deviation. The target 11 is fixed on the holder 18 of the workpiece 10, and emits visible fluorescence when irradiated with laser light other than visible light.

When investigating a positional shift, the X-Y stage 12 is moved to move the target 11 under the objective lens 9, and then a laser beam is irradiated at an appropriate scene. Then, as shown in FIG. 2, the camera 15 simultaneously observes an image of the fluorescence produced by the laser beam irradiation and an image of the guide light.

Then, the controller 173 sends a correction signal 174 corresponding to the magnitude of the deviation to the pulse motors 71 and 72, respectively, for aligning the aberration correction lens system 6, thereby performing appropriate alignment.

As a result, the deviation in the imaging position between the laser beam and the guide light is eliminated.

Pulse motors 71 and 72 for alignment of the aberration correction lens system 6 drive two orthogonal axes, X and Y, so that adjustment can be performed in a plane perpendicular to the optical axis of the guide light.

FIG. 2 is a schematic diagram showing the positional relationship between the fluorescence image 262 caused by the laser beam and the guide light image 201 on the target 11 and their No. 18 intensity.

The image signal 150 from the camera 15 is sent to the T”V monitor 16.
The image is sent to the controller 17 via the controller 17, and is loaded onto the internal image memory with gradations added. The positional deviation between the laser beam and the guide light can be determined by looking at the gradation of the image on the image memory 171.

In other words, if they match, there will be only one gradation difference around the image, but if there is a difference, there will be a part where the fluorescence and the guide light do not overlap, and this part is the intermediate part. This is because it appears as an r@ style of level. Therefore, the magnitude of the shift can be determined by checking the width of the intermediate gradation area.

In this case, the intensity of the image signal is the highest (I3) in a portion 203 where the guide light image 201 and the fluorescence @202 emitted by the target by laser beam irradiation overlap, but there is a difference in light intensity in the protruding portion 204. This causes the signal level to drop. Looking along X-X' in Figure 2, the length ΔXI or Δx2 of the part where the signal level takes an intermediate value (1 or I2) is the kite light and laser light in the X direction. This is the amount of positional deviation.

In addition, by making a difference in the brightness between the guide light and the fluorescence caused by the laser light, the signal level (1+ and I2) can be adjusted.
From this difference, it is possible to determine to which side the guide light is shifted relative to the laser light.

Furthermore, since the image is captured onto the image memory 171, exactly the same processing can be performed in the Y direction in the figure. In this case, the resolution of ΔX and Δy is Δx=0.08[μm], assuming that the resolution of the image memory 171 is 1024 x 960 and the field of view of the camera is φ80[μm].
m], Δy=0.065 [μm], so
The minimum resolution is 0.1 [μm] or less.

Furthermore, the A% procedure for alignment of the aberration correction lens system 6 will be explained using FIG. 5. FIG. 0 is a flowchart showing the procedure for adjusting the pulse motors 71 and 72 by the controller 17.

First, the deviation in the X-axis direction is measured, and according to the result, the X-axis pulse motor (for example, 71) in FIG. 2 is driven to correct the X-axis direction (step 5).
Step 502
>, the result is compared with a predetermined tolerance value (step 503).

If it is within the allowable value, then the pulse motor for the Y-axis direction (for example, 72) is driven to correct the Y-axis direction (step 504), and the deviation in the Y-axis direction is also measured and calculated again. (Step 505) and similarly compared with a predetermined tolerance value (Step 506).

In step 506, if the Y-axis direction is also within the tolerance, the deviation in the X-axis direction is checked again in step 507.
), if it is within the allowable value, the adjustment work is completed (steps 508→509).

On the other hand, in step 503, if it is outside the allowable value, it is checked whether the number of corrections is within a pre-limited number of times (step 503→
512), and if it is within the limited number of times, correction in the X-axis direction is performed again (step 512 → 501-502 →...
・・）0. If the number of times exceeds the limit, an error stop is notified and the work is completed (steps 512-513).

Furthermore, in step 506, if it is outside the allowable value, it is checked whether the number of corrections is within a pre-limited number of corrections (step 506).
06→510), and if it is within the limited number of times, correction in the Y-axis direction is performed again (step 51o→5°4→...
・). Furthermore, if the number of times exceeds the limit, an error stop notification is sent and the work is completed (step 51).
0 → 511).

In step 508, if it is outside the allowable value, the correction in the X-axis direction and the Y-axis direction is performed again from the beginning (step 508→501-+...).

By driving the step motors 71 and 72 as described above, the laser light and the guide light match, and highly accurate laser processing can be performed.

Further, another embodiment of the present invention will be described using FIG.

FIG. 3 is a block diagram showing the configuration of a second embodiment of the laser processing apparatus according to the present invention, in which parts equivalent to those in FIG. 1 are designated by the same reference numerals. (See Figure 1), the target is not placed below the objective lens. Further, the method of introducing the laser beam and the slit illumination light and the method of irradiating the workpiece with the laser beam and the guide light are the same as in the first embodiment shown in FIG.

In this embodiment, two mirrors 3.degree. 1 and 302 are provided in the aberration correction optical path. The mirror 301 serves as a half mirror for visible light, and the mirror 302 serves as a half mirror for laser light.
and are taken out respectively. And an imaging lens 303,
304 are used to form an image on a transmission target 305.

The rectangular slit image is transferred onto the transmission target 305 by enlarging it to the same size or several times. Transmit to the back. The transmitted light is observed by the camera 15, the same processing as in the first embodiment is performed by the controller 17, and the alignment of the aberration correction lens system 6 is corrected by driving the motor section 7, thereby achieving the first embodiment. The same effect can be obtained.

As explained above, the present invention detects the magnitude of the deviation in the imaging position of the laser beam and the guide light on the workpiece surface, and adjusts the aberration correction lens system according to the detection result. By correcting the alignment, it is possible to always match the guide light and the laser light with high precision, and there is an effect that the processing accuracy of the laser processing device can be maintained at a constant high level.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a laser processing apparatus according to a first embodiment of the present invention, and FIG. 2 shows the positional relationship between the fluorescence image and the kite light image directed to the target 1 by the laser beam, and their FIG. 3 is a schematic diagram showing the signal strength of the second embodiment of the present invention.
FIG. 4 is a block diagram showing the internal structure of the controller in FIG. 1, and FIG. 5 is a flowchart showing the adjustment procedure of the pulse motor by the controller. Explanation of symbols of main parts 1... Laser oscillator 4... Rectangular slit 6... Aberration correction lens system 7... Motor section 11...・Target 15...Camera 17...Controller

Claims (1)

[Claims] (1) A laser oscillator that emits laser light other than visible light, an imaging lens that forms an image of the laser light emitted from this laser oscillator on the processing surface, and visible light that confirms the irradiation position of the laser light. a guide light irradiation means for irradiating a guide light, the target being provided near the processing surface and emitting visible light when irradiated with the laser light; a detection means for detecting a deviation between the laser beam and the guide light when the light and the guide light are irradiated; and an irradiation position of the laser beam and an irradiation position of the guide light according to the deviation detected by the detection means; 1. A laser processing apparatus comprising: irradiation position correction means for matching the irradiation position.