JP2008119714A - Laser beam machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining apparatus capable of focusing an objective optical element for focusing or condensing laser beams on an object to be machined by using laser beam profiling. <P>SOLUTION: An observation substrate 14 having a reference measurement surface 13 with laser beams applied thereto is arranged on a beam observation device 1 provided on a laser beam machining apparatus 3. A CCD camera 15 is provided on the beam observation device 1, and an image monitor 20 for displaying the image picked up by the CCD camera 15 is connected thereto. The CCD camera 15 is focused on the reference measurement surface 13 so as to pick up an image of the shape of laser beam application to the reference measurement surface 13. Based on the shape of laser beam application on the reference measurement surface 13 image-picked up and displayed by the CCD camera 15, the objective optical element is focused on the reference measurement surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser processing apparatus including a beam observation apparatus capable of adjusting a focal position of a laser imaged or condensed on an object to be processed by an objective optical element.

In general, there is known a laser processing apparatus that performs various types of processing (welding, cutting, drilling, grooving, removal, and modification) on a workpiece by a laser (see, for example, Patent Document 1).
In addition, a technique for finely processing a thin film on the surface of a non-processed object to enable patterning of the thin film has been developed.
In such a laser processing apparatus, as shown in Patent Document 1, a height position of an optical element that focuses or focuses a laser on a non-processing object is set to a predetermined height position (non-processing object and Need to be adjusted). That is, it is necessary to adjust the height position of the optical element based on the image formation of the optical element and the focal length of the light collection.
Further, the irradiation shape of the laser processing object on the surface to be irradiated, that is, the cross-sectional shape of the laser beam is, for example, a circular shape or other shapes, and the cross-sectional shape (irradiation shape) of such a beam. A beam profiler having an imaging means having an imaging element such as a CCD or CMOS sensor as a device for measuring a spatial beam shape such as a beam diameter or a beam intensity distribution in a beam cross section or a spatial light intensity distribution. It is known, and is also used for measuring a beam cross-sectional shape of a laser in a laser processing apparatus (see, for example, Patent Document 2).

JP 2005-297012 A Japanese Patent Laid-Open No. 2003-078194

By the way, the focal length in the optical element may change depending on the situation because the optical element is deformed due to temperature or the like, and in processing the workpiece, an appropriate height position with respect to the workpiece is set. It is preferable to measure. Therefore, there has been a demand for a method for measuring the focal length of an optical element easily and with high accuracy.
On the other hand, the attenuated laser is directly incident on the beam profiler CCD camera. As a result, although it is possible to measure the spatial shape and intensity distribution of the beam from the laser imaged by the CCD camera, it was not possible to determine the appropriate height position of the optical element relative to the workpiece. .

Further, in the measurement of an ultraviolet light laser using a beam profiler, it is known to irradiate a fluorescent plate with an ultraviolet light laser and image the fluorescence generated thereby with a CCD camera.
In this case, the laser is imaged or condensed on the fluorescent plate by observing the shape of the fluorescent light on the fluorescent plate with a CCD camera while adjusting the position of the optical element that focuses or condenses the ultraviolet light laser on the fluorescent plate. It is conceivable to measure the height position of the optical element.

  In this case, it is difficult to accurately determine the image forming position and the focal position of the optical element with respect to the fluorescent plate because the fluorescent light on the fluorescent plate generated by the laser is observed instead of directly observing the laser. It was. In particular, the fluorescence observation shape on the fluorescent plate changes depending on the intensity of the laser beam and the characteristics of the fluorescent plate, and it is difficult to specify the exact imaging position and focal position.

  The present invention has been made in view of the above circumstances, and it is possible to easily and accurately determine the distance of an optical element that focuses or focuses a laser of a laser processing apparatus on a workpiece. An object of the present invention is to provide a laser processing apparatus provided with a beam observation apparatus capable of performing

  The invention according to claim 1 irradiates the laser beam to the object to be processed through an objective optical element for imaging or condensing a laser on the object to be processed, and the objective optical element A laser processing apparatus having a laser focus adjusting means for focusing a laser beam on an object to be processed, having a measurement reference plane on which a laser is irradiated as a temporary object to be processed and transparent to the wavelength of the laser A beam observing device having a highly observable substrate and an imaging means for imaging an irradiation shape of the laser on the measurement reference plane of the observation substrate, and irradiating the laser on the measurement reference plane imaged by the imaging means The focal position of the objective optical element can be determined by adjusting the focus of the objective optical element to the measurement reference plane by the laser focus adjusting means based on the shape.

In the first aspect of the invention, the laser is measured by the objective optical element by adjusting the laser focus adjusting means based on the laser irradiation shape (observation shape) on the measurement reference plane imaged by the imaging means. It can be imaged or focused on a surface. That is, the focal position (focal length) of the objective optical element with respect to the measurement reference plane can be determined.
In this state, the correspondence between the measurement reference plane and the objective optical element adjusted by the laser focus adjusting means is transferred to the workpiece and the objective optical element, so that the laser is accurately applied on the workpiece. Can be imaged or condensed. Specifically, when the laser focus adjusting means focuses on the distance between the objective optical element and the workpiece, the laser focus is adjusted by adjusting the distance between the measurement reference plane and the objective optical element. Later, the distance between the object to be processed and the objective optical element is set to the distance between the measurement reference plane at the time of focusing and the objective optical element.
Thus, when the laser is actually irradiated, the lens or the lens housing as the objective optical device is heated by the processing laser, and the lens material or the lens housing partially expands (thermal lens distortion) or the lens material. The focal length of the lens fluctuates due to a change in the refractive index caused by the temperature change, but if the focal length is adjusted as described above after a certain amount of time has elapsed after actually irradiating the laser, The focal length can be adjusted in a state similar to the state in which the focal length varies due to heat. Also, the focal length affected by heat can be adjusted by adjusting the focal length as described above during the processing or between the processing of the previous workpiece and the processing of the next workpiece. can do.

  According to a second aspect of the present invention, in the laser processing apparatus according to the first aspect, the display means for displaying the irradiation shape imaged on the imaging means, and the focus of the imaging means on the measurement reference plane of the observation substrate It is characterized by comprising a focus adjustment means for an image pickup device for matching, and a focusing pattern formed on the measurement reference plane of the observation substrate and used for focusing of the image pickup means.

According to the second aspect of the present invention, the focus of the imaging means is adjusted to the measurement reference plane by the imaging focus adjustment means in a state where the focusing pattern of the measurement reference plane is picked up by the imaging means and displayed on the display means. Thereafter, the measurement reference plane can be irradiated with the laser via the objective optical element, and the irradiated laser can be input to the imaging means via the measurement reference plane.
That is, with the focusing pattern formed on the measurement reference plane, first, the focus of the imaging means can be accurately focused on the measurement reference plane, and then the objective optical element can be focused as described above. The focal position of the objective optical element can be determined accurately.

  According to a third aspect of the present invention, in the laser processing apparatus according to the second aspect, a light pattern irradiating means for irradiating a pattern of light imaged on a measurement reference plane of the observation substrate as the focusing pattern; And a pattern image adjusting means for adjusting the light pattern by the light pattern irradiating means so as to form an image on the measurement reference plane.

  In the third aspect of the invention, when a focusing pattern is formed on the measurement reference plane by a thin film pattern formed by, for example, chromium vapor deposition, the pattern may be damaged by the laser. If the light pattern is accurately imaged and the light pattern is used as a focusing pattern, the focusing pattern is not damaged by the laser. That is, when a thin film pattern is used as the focusing pattern, for example, after adjusting the focus of the imaging means, the observation substrate having the measurement reference plane is shifted so as to move in parallel, and the laser is applied to the portion without the thin film pattern. Irradiation is performed, and this is imaged by an imaging means. If a light pattern is used, the pattern is not damaged by the laser, so there is no need to translate the observation substrate, and the beam observation apparatus. (Laser processing apparatus) can be simplified and laser focusing can be simplified.

  According to a fourth aspect of the present invention, in the laser processing apparatus according to any one of the first to third aspects, a power detector that detects an output of the laser that has passed through the measurement reference plane, and a laser that has passed through the measurement reference plane. And a beep splitter that branches to a power detector, wherein the beam splitter branches a part of the laser to the imaging means, and most of the laser branches to the power detector. .

  According to the fourth aspect of the present invention, it is possible to focus the objective optical element as described above in the beam observation apparatus capable of measuring the beam cross-sectional shape and the intensity distribution in the beam cross-section as profiling of the laser beam, The laser intensity can be measured. As a result, not only focusing of the objective optical element but also adjustment of the laser intensity of the laser can be monitored by the beam observation apparatus.

  According to the laser processing apparatus of the present invention, in the laser processing apparatus, it is possible to extremely easily and accurately perform the focusing of the objective optical element that focuses or focuses the laser on the workpiece.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows a schematic configuration of a laser processing apparatus 3 equipped with a beam observation apparatus (beam profiler apparatus) 1 according to the present invention.
The laser processing apparatus 3 includes the beam observation apparatus 1, an XY stage apparatus 4, a laser light source apparatus (not shown), and an object to be processed in which the laser irradiated from the light source apparatus is set on the XY stage apparatus 4. An objective optical device 6 provided with an imaging (condensing) lens as an objective optical element for imaging or condensing on the object 5, and supporting the objective optical device 6 so as to be movable up and down and in the vertical direction A Z stage device 7 that is positioned (on the Z axis) and a height sensor that measures the height as a distance along the Z axis direction from the fixed point to the workpiece 5 or the like on the XY stage device 4 8.

The light source device is, for example, a YAG laser (wavelength, 1064 nm, 532 nm, 355 nm, 266 nm), a CO2 laser (wavelength, 1.06 μm), an excimer laser (wavelength, 308 nm, 248 nm), other gas lasers, solids, etc. At least one of a laser, a semiconductor laser, a liquid laser, a fiber laser, a thin film disk laser, and the like can be used. That is, a suitable laser can be used according to the type of workpiece and the type of processing. The laser processing apparatus is used for at least one of welding / cutting / drilling / grooving / removal / modification, thin film patterning, sheet material processing, and the like. For example, the laser processing apparatus may be used for patterning a thin film on a transparent substrate such as a glass substrate or a resin substrate (film) of a flat panel display.
Note that lasers suitable for fine processing by a laser are a laser of 157 nm to 1200 nm and an infrared laser of 9 μm to 11 μm.

  The XY stage device 4 is a well-known one, and basically includes a stage 41 on which a plate-like or sheet-like workpiece 5 is set. The stage 41 is placed in the X-axis direction and a Y-axis orthogonal thereto. An XY stage control device 42 that controls the movement of the stage 41 is provided. Further, the XY stage apparatus 4 is provided with a fixed portion 43 formed in a gate shape so as to straddle the stage 41, and the Z stage apparatus 7 provided with the objective optical device 6 in the fixed portion 43; A height sensor 8 is fixed.

The objective optical device 6 and the height sensor 8 move any of the entire upper surface of the workpiece 5 fixed to the stage 41 by moving the stage 41 within the movable range of the XY stage device 4. Can be arranged right above the beam, and can be arranged at least directly above the measurement reference plane 13 to be described later of the beam observation apparatus 1.
The objective optical device 6 is a well-known device including a lens (objective lens) or a lens group as an optical element that focuses or focuses a laser on the workpiece 5 as described above.
The Z stage device 7 moves the objective optical device 6 in the Z-axis direction (the irradiation direction of the processing laser) orthogonal to the X-axis direction and the Y-axis direction. The distance between the apparatus 6 (lens) and the workpiece 5 is adjusted, and the laser beam is focused or focused on the workpiece 5 by an imaging or focusing lens. That is, the Z stage device 7 functions as a laser focus adjusting means for focusing the objective optical device 6 including the objective optical element on the workpiece 5.

  Therefore, the laser processing device 3 irradiates the workpiece 5 with the laser via the objective optical element (objective optical device 6) for imaging or condensing the laser on the workpiece 5. And it has a laser focus adjustment means for adjusting the focus of the objective optical element to the workpiece 5. The Z stage device 7 is controlled by the Z stage control device 71 to move the objective optical device 6.

  The height sensor 8 (off-axis height sensor) is a well-known sensor that measures the position of the upper surface (laser irradiation surface) of the workpiece 5 in the Z-axis direction in contact with the workpiece. 5 and the Z-axis direction position (height) of the measurement reference surface 13 of the observation substrate 14 to be described later, and the Z-axis position of the upper surface of the workpiece 5 are calculated. The height sensor 8 is connected to a height measurement monitor 81 that displays the measured position in the Z-axis direction. The measurement value of the height sensor 8 is output from the height measurement monitor 81 to the Z stage control device 71. The Z stage control device 71 moves the objective optical device 6 up and down based on the measurement value of the height sensor 8. Can be moved to.

The laser beam observation apparatus 1 used in such a laser processing apparatus 3 does not get in the way of setting the workpiece 5 of the stage 41 of the XY stage apparatus 4 as shown in FIG. It is fixed to one side edge and can move in the X-axis direction and the Y-axis direction integrally with the stage 41. The beam observation device (beam profiler device) 1 is divided into a measurement unit 11 fixed to the stage 41 and a monitor unit 12 for monitoring the measurement result, and is connected and fixed to the stage 41. Only the measuring unit 11 is used.
Note that the beam observation apparatus 1 according to the present invention may be considered to be included in a broad beam profiler that images the spatial shape and intensity distribution of a beam with an imaging element such as a CCD element or a CMOS sensor element.

  As shown in FIG. 2, the measurement unit 11 of the beam observation apparatus 1 includes an observation substrate 14 having a measurement reference plane 13 irradiated with a laser, and a laser irradiated on the observation substrate 14 with a CCD camera described later. 15 and a beam splitter 17 that branches to a power detector 16 that detects the output of the laser, and a laser irradiated to the measurement reference plane 13, thereby measuring the irradiation shape of the laser and the intensity distribution in the irradiation shape. The CCD camera 15, the power detector 16 used for measuring the output of the laser, and the slit plate 19 as a light pattern irradiating means for irradiating the measurement reference plane 13 with a light pattern for focusing the CCD camera 15. And a CCD camera illumination device 34. Instead of the CCD camera 15, a digital camera using another image sensor such as a CMOS sensor may be used.

  The monitor unit 12 is connected to the CCD camera 15, and displays an image monitor 20 that displays an image captured by the CCD camera 15, and a laser output value based on a signal connected to the power detector and measured by the power detector 16. And an output measurement monitor 21 to be displayed. Here, the image monitor 20 is a display unit that displays the irradiation shape on the measurement reference plane 13 of the laser imaged by the CCD camera 15 as the imaging unit.

The observation substrate 14 is made of, for example, glass, quartz, or the like, and the material is determined by the wavelength of the laser used, and a substrate that is extremely transparent to the laser is used as the observation substrate 14. It is done. That is, the observation substrate 14 is made of a material that is not processed (damaged) by the laser and that attenuates the passing laser as much as possible, and is determined by the wavelength of the laser.
For example, in the case of an excimer laser, a quartz plate is used as the observation substrate 14.
In the case of a CO2 laser, zinc selenium (ZnSe ... Zinc Selenide) can be preferably used.
From the above, the beam observation apparatus 1 includes the measurement reference surface 13 on which the laser is irradiated as a temporary workpiece, and includes the observation substrate 14 that is highly transparent with respect to the wavelength of the laser.

The observation substrate 14 is basically a rectangular plate whose thickness is as uniform as possible, and the upper surface irradiated with the laser is a measurement reference surface 13 that is as flat as possible.
A test pattern 23 made of a chromium thin film is formed on the measurement reference surface 13 on one side, for example, the left side of the left and right halves. The test pattern 23 is for adjusting the focus of the CCD camera to the measurement reference plane, and is formed in, for example, a vertical and horizontal grid pattern. That is, the test pattern 23 is a focusing pattern that is formed on the measurement reference plane 13 of the observation substrate 14 and is used for focusing of the CCD camera 15 as an imaging unit.

  The observation substrate 14 is supported by an observation substrate uniaxial moving mechanism (not shown) that can move the observation substrate in the left-right direction. Therefore, the observation substrate 14 is positioned at the position where the laser is irradiated, that is, the position imaged by the CCD camera 15, the position where the test pattern 23 is formed, and the test pattern 23 is not formed. Switching is possible between the position where the substrate 14 is exposed in a planar shape.

The beam splitter 17 is basically a plate having a very high transparency with respect to the laser. However, the beam splitter 17 is disposed obliquely with respect to the laser, and transmits and reflects light at the interface between the air and the beam splitter 17. Will be separated. The transmitted light is incident on the power detector 16 and the reflected light is incident on the CCD camera 15.
At this time, the reflected light of the laser incident on the CCD camera 15 is preferably as small as possible, and the light incident on the power detector 16 is preferably as large as possible.
That is, the sensitivity of the CCD camera 15 is extremely high with respect to a laser having a large output, and it is sufficient that only a very small part of the laser output is incident. If too much, the CCD camera 15 may be destroyed.

On the other hand, in the power detector 16, in order to accurately measure the laser output, it is preferable that a laser that is not attenuated as much as possible is incident.
In other words, the beam splitter 17 branches a part of the laser to the CCD camera 15 and branches most of the laser to the power detector 16.
Further, since the amount of laser light incident on the CCD camera 15 may be very small, the surface of the beam splitter 17 irradiated with the laser is coated with a known coating that suppresses the reflected light so as to reduce the reflected light. It may be.

  The CCD camera 15 and a pattern illumination 18 (to be described later) are arranged in the same lens barrel 24. The lens barrel 24 is provided with an objective lens 25, and the laser branched by the beam splitter 17 enters the lens barrel 24 through the objective lens 25. The CCD camera 15 is disposed at a position offset with respect to the incident axis of the laser incident from the objective lens 25, and the light reflected by the two mirrors 26 and 27 disposed from the objective lens 25 is CCD. The light enters the camera 15 through the lens 28.

The mirror 26 disposed on the optical axis of the objective lens 25 is a transparent plate, reflects the incident laser, and transmits the light of the pattern illumination 18 as will be described later. It has the same configuration as a beam splitter or dichroic mirror.
The laser incident on the CCD camera 15 has a small output by the beam splitter 17 as described above, and a filter 29 (for example, a neutral density (ND) filter) is further disposed. The incident laser is further dimmed by the filter 29 to protect the CCD camera 15.
Further, a pattern illumination 18 having the slit plate 19 is disposed on the optical axis of the objective lens 25 in the lens barrel 24, and passes through the mirror 26 through a lens 30 (for example, a collimator lens). The objective lens 25 forms an image of the shape of a slit (for example, a cross) formed on the slit plate 19 on the measurement reference plane 13 of the observation substrate 14.
In addition, the shape irradiated by pattern illumination is not limited to the cross, but may be any shape that can be used for focusing. Therefore, the pattern is not limited to the slit plate 19 having slits, but may be one that can form a light pattern with a mask such as a metal mask or a glass photomask. It suffices if an image can be formed by projecting on the reference surface 13.

  That is, the pattern illumination 18 and the CCD camera 15 share the objective lens 25. The slit plate 19 is movable between the pattern illumination 18 and the lens 30 along these optical axes. By moving the slit plate 19, the slit plate 19 moves to the measurement reference plane of the observation substrate 14. The shape of the slit plate 19 can be imaged. That is, the focus can be adjusted. The slit plate 19 can be moved from the outside of the lens barrel 24 by an operation.

From the above, the CCD camera 15 serves as an imaging means for imaging the irradiation shape of the laser on the measurement reference plane 13 when the laser attenuated while passing through the measurement reference plane 13 of the observation substrate 14 is incident.
Further, the measurement standard of the observation substrate 14 is used as a focusing pattern of the CCD camera 15 from the slit plate 19 and the pattern illumination 18 and the optical system parts such as the lens 30, the objective lens 25, and the beam splitter 17 functioning as a mirror. A light pattern irradiating unit that irradiates a light pattern to be imaged on the surface 13 is configured, and a mechanism for moving the slit plate 19 to adjust the light pattern by the light pattern irradiating unit to form an image on the measurement reference plane It becomes an imaging adjustment means.

In addition, the lens barrel 24 in which the CCD camera 15, the pattern illumination 18, and the like are housed is movable along the optical axis direction of the laser branched toward the CCD camera 15 by the beam splitter 17. It is supported by a focal position control device 31 having a single axis stage. The focal position control device 31 serves as an imaging device focus adjustment unit for focusing the CCD camera 15 as an imaging unit on the measurement reference plane 13 of the observation substrate 14.
That is, the CCD camera 15 is moved along the optical axis direction of the incident laser including its optical system (objective lens 25, lens 28, etc.), so that the focus of the CCD camera 15 is a measurement standard of the observation substrate 14. It can be adapted to the surface 13.

A laser branched by the beam splitter 17 is incident on the power detector 16 via a mirror 32 and a lens 33 (for example, a condensing lens).
The power detector 16 is for a known laser and detects the output of the irradiated laser. In the case where the laser used is pulsed, a detector capable of detecting the output of a known pulsed laser may be used.
That is, the power detector 16 detects the output of the laser that has passed through the measurement reference plane 13. The beam splitter 17 branches the laser that has passed through the measurement reference plane 13 into a CCD camera 15 and a power detector 16.
Further, the beam observation apparatus 1 includes a CCD camera illumination device 34, and the illumination light of the CCD camera illumination device 34 passes through the beam splitter 17 and the mirror 32 (dichroic mirror) to be measured. The test pattern 23 is irradiated.

In the laser processing device 3 as described above, the beam observation device 1 is used to focus the objective optical device of the laser processing device 3 as follows.
First, the observation substrate 14 is moved by the observation substrate uniaxial moving mechanism so that the test pattern 23 on the measurement reference plane 13 is arranged at the center of the imaging range of the CCD camera.
Next, the CCD camera 15 captures the test pattern 23, displays the captured test pattern 23 on the image monitor 20, and operates the focus control device 41 while viewing the test pattern 23 on the image monitor 20 to operate the lens barrel 24. Is moved in the direction of the optical axis of the laser incident on the lens barrel 24 so that the CCD camera 15 is focused.

  With the CCD camera 15 in focus, the observation substrate 14 is then moved so that the portion of the observation substrate 14 where the test pattern 23 is not formed is within the imaging range of the CCD camera 15. Note that the position of the observation substrate 14 at this time is a position at which laser profiling is performed. Then, the pattern illumination 18 is turned on and the slit plate 19 is moved to project the cross slit shape formed on the slit plate 19 on the measurement reference plane of the observation substrate 14 and to focus the pattern.

As a result, the pattern illumination 18 is turned on during imaging by the CCD camera 15, and the CCD camera 15 is focused on the measurement reference plane 13 by checking with the image monitor 20 of the projected slit of the measurement reference plane 13. It can be confirmed whether or not.
Basically, if the projected slit is in focus when looking at the measurement reference plane 13, the CCD camera 15 is in focus.

Next, the stage 41 of the XY stage apparatus 4 is moved by the operation of the XY stage control apparatus 42, and the objective is placed at the center of the imaging range of the CCD camera 15 on the measurement reference plane 13 of the beam observation apparatus 1. It adjusts so that the laser irradiated via the optical apparatus 6 for irradiation may be irradiated. Then, the measurement reference plane 13 is irradiated with a laser.
As a result, the CCD camera 15 focused on the measurement reference plane 13 captures an image indicating the irradiation shape of the laser irradiated on the measurement reference plane 13 and the intensity distribution of the laser within the irradiation shape, and is displayed on the image monitor 20. Is displayed.

  The objective optical device 6 is moved by the Z stage device 7 while observing the irradiation shape and intensity distribution on the measurement reference surface 13 displayed on the image monitor 20, so that a laser is imaged or condensed on the measurement reference surface 13. Adjust so that. That is, the focus of the laser objective optical device 6 is adjusted to the measurement reference plane 13. At this time, the focal position (imaging position or condensing position) of the objective optical device 6 in which the laser is in focus on the measurement reference plane 13 is determined, and the measurement reference in which the laser is in focus on the measurement reference plane 13 is determined. The distance between the surface 13 and the objective lens of the objective optical device 6 is determined.

On the other hand, the height position between the upper surface of the workpiece 5 and the measurement reference surface 13 is measured by the height sensor 8, and the difference in height position between the upper surface of the workpiece 5 and the measurement reference surface 13 is measured. The focal point of the objective optical device 6 is focused on the workpiece 5 by moving the position of the objective optical device 6 focused on the measurement reference plane 13 by the difference of the height position as described above. Can be matched.
At this time, in the objective optical device 6, since the temperature of the lens and the lens housing is changed by the laser irradiation, the shape of the lens and the refractive index of the lens material are changed due to the temperature change. When the laser is irradiated, the focal position is shifted. Therefore, the processing accuracy by the laser can be improved by actually measuring the focal position as described above and performing the processing by the laser. Note that the focal position of the objective optical device 6 may be determined after the laser is output for a certain period of time, or the height of the objective optical device 6 is measured by measuring the focal position even during the processing operation. The position may be adjusted again.

  As described above, according to the beam observation apparatus 1, the laser beam is applied to the measurement reference plane 13 while the CCD camera 15 is focused on the measurement reference plane 13 using the focal position control apparatus 31 while imaging the test pattern 23. The objective optical device can be focused on the measurement reference plane 13 using the Z stage device 7 based on the laser irradiation shape on the measurement reference plane 13 that is imaged and displayed.

  Further, the power detector 16 can measure the intensity of the laser when the laser is irradiated. Thereby, it can be measured whether the intensity | strength of a laser exists in the range suitable for processing. Also at this time, since the laser output changes due to the deformation of the above-described lens, the secular change of the light source device, etc., in actual processing, the output is measured to determine whether the output is appropriate. When the output is not appropriate, the output of the light source device can be adjusted.

  From the above, according to the beam observation apparatus of the present invention, not only the measurement of the beam profile of the laser in the laser processing apparatus, that is, the measurement of the irradiation shape and the intensity distribution described above, is possible. It is possible to determine the focal position (imaging position or condensing position), that is, focus, and to measure and adjust the laser intensity.

  In the above example, the laser processing apparatus that moves the workpiece 5 with respect to the laser using the XY stage apparatus 4 at the time of processing is shown as the laser processing apparatus. The present invention can also be applied to other laser processing apparatuses, and can be applied to all laser processing apparatuses that require focusing of the objective optical device 6 and laser intensity adjustment. The present invention can also be applied to a laser processing apparatus that moves a laser and a laser processing apparatus that can move both the workpiece 5 and the laser.

  Further, the beam observation apparatus 1 may not include the power detector 16 and the beam splitter 17 that branches the light to the power detector 16. Further, the light pattern irradiating means and the pattern imaging adjusting means comprising the slit plate 19 (or mask) for projecting the test pattern for the CCD camera 15 on the measurement reference plane 13 and the pattern illumination 18 may be omitted. . In the lens barrel 24, the CCD camera 15 may be disposed on the optical axis of the objective lens 25, and the slit plate 19 and the pattern illumination 18 may be disposed at positions offset from the optical axis. In the above example, the surface (upper surface) on the observation substrate 14 on which the laser is incident is used as the measurement reference surface 13, but the surface (lower surface) on the side from which the laser that has passed through the observation substrate 14 is emitted is used. The measurement reference plane 13 may be used.

Further, the light pattern irradiating means and the pattern imaging adjusting means for projecting the test pattern are accommodated in the same lens barrel 24 as the CCD camera 15 and the objective lens 25 is shared with the CCD camera 15. The pattern irradiating means and the pattern image forming adjusting means may be arranged outside the lens barrel 24 for the CCD camera 15.
Further, in this case, the light pattern irradiating means and the pattern imaging adjusting means can project the test pattern onto the measurement reference plane 13 completely independently of the CCD camera 15 and can focus the measurement pattern. After the focus of the test pattern projected in step S3, the CCD camera 15 can be focused, and there is no need to provide a fixed test pattern 23 on the measurement reference plane 13. In this case, since the test pattern 23 provided on the measurement reference surface 13 is not damaged by the laser, it is not necessary to move the observation substrate 14 as described above, and the configuration of the beam observation apparatus 1 is simplified. Can be

In the above example, the lens barrel 24 is moved so that the CCD camera 15 is focused on the measurement reference plane 13. However, by moving the optical system components such as the objective lens 25 and the lens 28, the CCD camera 15 is focused. The camera 15 may be focused. In this case, the means for moving the optical system component becomes the focus adjustment means for the imaging apparatus.
Further, when the objective optical device 6 is focused based on the irradiation shape on the measurement reference plane 13, the irradiation shape in focus is imaged and stored in advance, and the stored irradiation shape and the image are captured. By comparing the irradiation shape with a known image recognition means, the objective optical device 6 is automatically moved by the Z stage device 7 so that the imaged irradiation shape approaches the stored irradiation shape, It is good also as what automates focusing.

It is the schematic which shows the laser processing apparatus provided with the beam observation apparatus which concerns on embodiment of this invention. It is the schematic which shows the said beam observation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Beam observation apparatus 3 Laser processing apparatus 5 Object to be processed 6 Objective optical apparatus (objective optical element)
7 Z stage device (laser focus adjustment means)
13 Measurement reference plane 14 Observation substrate 15 CCD camera (imaging means)
16 Power detector 17 Beam splitter 18 Pattern illumination 19 Slit plate 20 Image monitor (display means)
31 Focus position control device (focus adjustment means for imaging device)

Claims (4)

The laser beam is irradiated onto the workpiece through an objective optical element for imaging or condensing a laser on the workpiece, and the focal point of the objective optical element is focused on the workpiece. A laser processing apparatus having a laser focus adjusting means for
An observation substrate having a measurement reference surface irradiated with a laser as a temporary workpiece and having high transparency with respect to the wavelength of the laser;
A beam observation device having imaging means for imaging the irradiation shape of the laser on the measurement reference plane of the observation substrate;
Based on the laser irradiation shape on the measurement reference plane imaged by the imaging means, the focus position of the objective optical element is adjusted to the measurement reference plane by the laser focus adjustment means. A laser processing apparatus characterized in that it can be determined. Display means for displaying the imaged irradiation shape on the imaging means;
A focus adjustment means for an imaging device for focusing the imaging means on a measurement reference plane of the observation substrate;
The laser processing apparatus according to claim 1, further comprising: a focusing pattern formed on a measurement reference plane of the observation substrate and used for focusing of an imaging unit. A light pattern irradiating means for irradiating a pattern of light imaged on the measurement reference plane of the observation substrate as the focusing pattern;
The laser processing apparatus according to claim 2, further comprising: a pattern image adjusting unit that adjusts the light pattern emitted from the light pattern irradiating unit to form an image on the measurement reference plane. A power detector for detecting the output of the laser that has passed through the measurement reference plane;
A beep splitter that branches the laser that has passed through the measurement reference plane to the imaging means and a power detector;
4. The laser processing apparatus according to claim 1, wherein the beam splitter branches a part of a laser beam to an imaging unit and branches most of the laser to a power detector. 5.

Images