JP2011060832A - Laser irradiation device having tilt control mechanism and tilt control method in laser irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser irradiation device having a tilt control mechanism, and a tilt control method in the laser irradiation device. <P>SOLUTION: A pair of optical systems for irradiation and a pair of AF optical systems are provided in the laser irradiation device, and tilt of the irradiation surface of an object to be irradiated is adjusted automatically while maintaining uniform irradiation by performing drive control of the optical head in the tilt direction based on the quantity of the return light which is received by each AF optical system. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser irradiation apparatus that irradiates a laser beam while performing focus control on the irradiation object, and in particular, tilt control that automatically controls the irradiation position and irradiation direction according to the displacement of the irradiated surface of the irradiation object. The present invention relates to a method and a laser irradiation apparatus having the tilt control mechanism.

  Generally, a laser irradiation apparatus is used in a laser annealing apparatus or the like that changes a physical characteristic of an irradiation object by irradiating a laser spot focused on the irradiation object.

  As shown in FIG. 9, a laser irradiation apparatus that performs laser spot focus control according to the prior art includes a plurality of semiconductor laser elements 1a to 1n that emit laser beams and laser beams emitted from the plurality of semiconductor laser elements 1a to 1n. A plurality of optical fibers 2 on which the beam is incident at one end and a plurality of laser beams emitted from the other end of each optical fiber 2 are incident on one side surface, and are guided from the other side surface while irregularly reflecting the laser beam inside. An optical plate 13, a collimating lens 14 that converts the laser beam emitted from the light guide plate 13 into parallel light, and an objective that condenses the laser beam that is parallel light emitted from the collimating lens 14 and irradiates the irradiation object 20. PBS (polarized beam splitter) that polarizes the traveling direction of the reflected light from the lens 16 and the irradiation object 20 by 45 degrees. : A filter that separates incident light by its polarization component) 15, an AF (autofocus) condenser lens 12 that condenses the laser beam polarized by the PBS 15, and return light 17 condensed by the condenser lens 12. And an autofocus (AF) control unit (not shown) that performs focusing on the irradiation target 20 by the astigmatism method based on the return light 17 received by the detector 11.

  The astigmatism method described above is a method for measuring the displacement in the optical axis direction in a non-contact manner by detecting distortion of a point image formed by an optical system having astigmatism, and the focal length of the lens. Using astigmatism due to having different values in two orthogonal cross sections including the optical axis, and combining point images in an optical system with this astigmatism, the image is vertically long, circular, This is a technique for measuring the displacement in the optical axis direction by detecting the change using a four-divided photodetector.

  The laser irradiation apparatus configured in this manner polarizes the laser beam reflected from the irradiation object 20 by the PBS 15 and stops it by the AF condensing lens 12, which is received by the detector 11, and receives a control signal from the autofocus control unit. By moving the objective lens 16 with respect to the irradiation target 20 based on the above, the laser spot on the irradiation target 20 is controlled to be focused.

  In addition, the following patent document is mentioned as a literature in which the technique regarding the laser annealing apparatus mentioned above was described. Patent Document 1 describes a technique for crystallizing a semiconductor film by irradiating a laser to an amorphous semiconductor film, and Patent Document 2 describes a laser beam irradiated from a plurality of semiconductor laser elements as an optical fiber. Describes a technique for irradiating an irradiation target with a laser spot that is incident on one end of a plate-like optical waveguide via a laser beam and focused by a focusing lens on a laser beam emitted from the other end of the optical waveguide.

JP 2004-241421 A JP 2007-115729 A

In the conventional laser irradiation apparatus shown in FIG. 9, the focus control optical system is different from the irradiation optical system configured linearly from the semiconductor laser elements 1a to 1n, which are light sources, to the irradiation target 20. An optical path must be provided, and the overall structure of the optical head unit 10 becomes complicated, large, and heavy. Here, as shown in FIG. 9, the optical head unit 10 includes a light guide plate 13, a collimating lens 14, an objective lens 16, an AF condensing lens 12, a detector 11, and a driving unit (not shown) for the objective lens 16. Etc.
When the weight of the optical head unit 10 increases, focus control may become unstable due to vibration caused by movement of the optical head unit 10. Particularly, in a laser irradiation apparatus used for annealing (crystallization) of a large liquid crystal panel, it is required to perform uniform irradiation without shifting the focus of the irradiation beam. Therefore, the optical head unit 10 is reduced in weight and focus control is performed. Stabilization is an important issue.

Accordingly, the present inventors have devised a laser irradiation apparatus having an apparatus configuration that does not require a focus control optical path different from the irradiation optical system.
FIG. 10 is a diagram schematically showing the configuration of this laser irradiation apparatus. As shown in FIG. 10, this laser irradiation apparatus includes a pair of laser light emitting portions 6a and 6b each having semiconductor laser elements 1a and 1b and coupling lenses 4a and 4b that emit laser beams, and laser light emitting portions 6a and 6b, respectively. A pair of optical fibers 2 to which the laser beam emitted from one end is incident at one end, and a plurality of laser beams emitted from the other end of each of the optical fibers 2 are incident on one side surface, and the laser beams are diffusely reflected inside. While collimating the light guide plate 13 emitted from the other side surface, the collimating lens 14 for converting the laser beam emitted from the light guide plate 13 into parallel light, and condensing the laser beam as parallel light emitted from the collimating lens 14. The objective lens 16 that irradiates the irradiation object 20 and the light reflected from the irradiation object 20 and incident on the light guide plate 13. The return optical fiber 5 for guiding the user beam to the outside from the substantially central portion of one side surface of the light guide plate 13, the AF optical system 30 to which the laser beam emitted from the other end of the return optical fiber 5 is incident, and the AF optical system 30 An AF control unit 35 that outputs a control signal for controlling driving of the objective lens 16 based on the output signal.
The AF optical system 30 has the same AF condensing lens and detector as those shown in FIG.

  The laser irradiation apparatus shown in FIG. 10 can perform automatic focusing by driving and controlling the objective lens 16 in a direction perpendicular to the irradiation surface of the irradiation object by the same operation as the laser irradiation apparatus shown in FIG. . As is clear from a comparison between FIG. 10 and FIG. 9, the laser irradiation apparatus shown in FIG. 10 separates the AF optical system 30 from the linearly configured irradiation optical system, thereby enabling the optical head unit 70 to be It avoids complication, enlargement, and weight.

  FIG. 11 is a diagram showing the waveform of the signal MONC (central monitor signal) output from the detector of the AF optical system 30. As shown in FIG. The signal MONC is a value corresponding to the amount of return light received by the detector, and is the maximum value when the focal point of the laser spot 7 coincides with the surface of the irradiation target 20. Therefore, the AF controller 35 drives and controls the objective lens 16 so that the value of the signal MONC from the detector becomes the maximum value, whereby the laser spot 7 can be focused on the surface of the irradiation object 20. Actually, as shown in FIG. 11, the AF control unit 35 performs control so that the value of the signal MONC from the detector exceeds a predetermined threshold VC (for example, 90% of the maximum output level). Also good.

By the way, in a laser irradiation apparatus for performing laser annealing, an excimer laser generated by using a mixed gas such as a rare gas or a halogen, or a laser beam having a high energy density at a short wavelength such as a semiconductor laser is extremely highly condensed. The object to be irradiated is irradiated in focus. Irradiation light having a very high degree of concentration has a very shallow depth of focus.
In the laser irradiation apparatus shown in FIG. 10, focusing is performed by displacing the focus of the irradiation light in a direction perpendicular to the irradiation surface of the irradiation object based on the return light detected by the detector of the AF optical system 30. However, when the displacement of the irradiation surface of the irradiation object is large (for example, displacement of 20 to 30 μm), the properties such as the energy density of the irradiation light greatly change due to the adjustment of the objective lens 16, and the irradiation object There was a problem that uniform irradiation could not be performed on an object.

  Further, in order to irradiate a minutely irradiated portion of the irradiation target with a laser spot having a very shallow depth of focus with a sufficient intensity distribution, it is necessary to irradiate the laser spot perpendicularly to the irradiation target. In the laser irradiation apparatus shown in FIG. 1, there is a problem that there is no means for detecting the tilt of the irradiation surface of the irradiation object, and the irradiation direction (optical axis) cannot be adjusted according to the tilt. It was. Further, in the laser irradiation apparatus shown in FIG. 10, only the focus adjustment in the vertical direction with respect to the irradiation surface of the irradiation object can be performed, and the horizontal / There was also a problem that vertical position adjustment was not possible.

Even in the prior arts described in the above patent documents, such a problem is not solved, and it is not even conscious to deal with it as a problem.
In view of the above circumstances, the present invention aims to provide a laser irradiation apparatus having a tilt control mechanism and a tilt control method in the laser irradiation apparatus in order to solve the problems in the conventional laser irradiation apparatus described above. To do.

  As a result of diligent research in view of the above problems, the present inventor noticed that the laser spot has a certain spread (usually an ellipse), and in the laser irradiation apparatus, a pair of irradiation optical systems and a pair of AF optics. A system is provided, and the optical head is driven and controlled in the tilt direction based on the amount of return light received by each AF optical system, thereby automatically adjusting the tilt of the irradiation surface of the irradiation object while maintaining uniform irradiation. The idea of what can be done has led to the present invention.

  That is, the present invention is a laser irradiation apparatus for irradiating an irradiation target with a laser spot obtained by condensing a laser beam, and includes a plurality of irradiation optical systems including means for emitting laser light, and each of the irradiation optical systems A collimating lens that receives irradiated laser light and condenses it into parallel light, and an objective lens that condenses the laser light that has passed through the collimating lens into a predetermined laser spot shape and focuses it on the irradiation surface of the irradiation object. And a plurality of return optical systems that receive the return light that is reflected by the laser light applied to the irradiation object and that has passed through the objective lens and the collimator lens, and the return light received by each of the return optical systems And means for adjusting the irradiation direction of the laser spot on the irradiation object based on the detected amount of return light. There is provided a laser irradiation apparatus.

In the laser irradiation apparatus of the present invention, the irradiation direction adjusting means adjusts the irradiation direction of the laser spot while fixing the focal point on the irradiation surface of the irradiation object.
As a result, it is possible to adjust the irradiation direction without shifting the focal position on the irradiation surface of the irradiation target and to perform good irradiation.

  The laser irradiation apparatus of the present invention further includes an optical head unit that accommodates the collimating lens and the objective lens, and the irradiation direction adjusting means has a focal point on the irradiation surface of the irradiation object as a central axis. The irradiation direction of the laser spot is adjusted by rotating the optical head portion around the central axis.

In the laser irradiation apparatus of the present invention, the irradiation direction adjusting means adjusts the irradiation position on the irradiation object by adjusting the position of the optical head in a direction parallel to and perpendicular to the irradiation surface of the irradiation object. It is characterized by doing.
Thereby, not only the adjustment of the irradiation direction but also the shift of the focal position on the irradiation object can be adjusted.

In the laser irradiation apparatus of the present invention, the irradiation direction adjusting means may adjust the irradiation direction of the laser spot and / or the irradiation target so that the total value of the amount of return light received by each of the return optical systems becomes a maximum value. Alternatively, the irradiation position on the irradiation object is adjusted.
Alternatively, the irradiation direction adjusting means may adjust the irradiation direction of the laser spot and / or the irradiation object so that the total amount of the return light received by each of the return optical systems is equal to or greater than a predetermined threshold value. The upper irradiation position may be adjusted.

  The laser irradiation apparatus of the present invention further includes moving the objective lens in a direction substantially perpendicular to the irradiation surface of the irradiation object based on the amount of the detected return light, thereby focusing the laser spot on the irradiation object. It has a focus adjustment means for performing alignment.

  The present invention also includes a plurality of irradiation optical systems having means for emitting laser light, a collimating lens that receives the laser light irradiated from each of the irradiation optical systems and collects the collimated light, and the collimating lens. An objective lens that focuses the laser beam that has passed into a predetermined laser spot shape and focuses it on the irradiation surface of the irradiation target, and the laser beam irradiated to the irradiation target is reflected, and the objective lens and the collimating lens In the laser irradiation apparatus having a plurality of return optical systems that receive the return light that has passed through and means for detecting the amount of the return light received by each of the return optical systems, the amount of the detected return light The laser irradiation method is characterized in that the irradiation direction of the laser spot on the irradiation object is adjusted based on the above.

The laser irradiation method of the present invention is characterized in that the irradiation direction of the laser spot is adjusted while fixing the focal point on the irradiation surface of the irradiation object.
As a result, it is possible to adjust the irradiation direction without shifting the focal position on the irradiation surface of the irradiation target and to perform good irradiation.

  The laser irradiation method of the present invention includes an optical head unit that accommodates the collimating lens and the objective lens in the laser irradiation apparatus, and the central axis is a focal point on the irradiation surface of the irradiation object. On the other hand, the irradiation direction of the laser spot is adjusted by rotating the optical head portion.

The laser irradiation method of the present invention is characterized in that the irradiation position on the irradiation object is adjusted by adjusting the position of the optical head in a direction parallel to and perpendicular to the irradiation surface of the irradiation object.
Thereby, not only the adjustment of the irradiation direction but also the shift of the focal position on the irradiation object can be adjusted.

  In the laser irradiation method of the present invention, the irradiation direction of the laser spot and / or irradiation on the irradiation object is performed so that the total value of the amount of the return light received by each of the return optical systems becomes the maximum value. The position is adjusted.

  Alternatively, the irradiation direction of the laser spot and / or the irradiation position on the irradiation object is adjusted so that the total amount of the return light received by each of the return optical systems is equal to or greater than a predetermined threshold value. It is good as well.

  The laser irradiation method of the present invention focuses the laser spot on the irradiation target by moving the objective lens in a direction substantially perpendicular to the irradiation surface of the irradiation target based on the amount of the detected return light. It is characterized by performing.

  As described above, according to the laser irradiation apparatus having the tilt control mechanism of the present invention and the tilt control method in the laser irradiation apparatus, the irradiation direction of the laser beam is automatically adjusted with respect to the inclination of the irradiation surface of the irradiation object. And suitable irradiation can be performed.

It is a figure which shows roughly the whole structure of the laser irradiation apparatus which has a tilt control mechanism concerning one Embodiment of this invention. It is a schematic diagram for demonstrating the fluctuation | variation (tilt) of the irradiation target object which arises in a laser irradiation apparatus, and the coping method with respect to it. It is a schematic diagram for demonstrating the laser spot and irradiation method on the irradiation target object in the laser irradiation apparatus shown in FIG. It is a figure which shows the waveform of the synthetic | combination signal MONL + MONR of each signal output from a pair of AF optical system in the laser irradiation apparatus shown in FIG. It is a schematic diagram for demonstrating the drive method of the θ-axis direction of the optical head part by the tilt control part in the laser irradiation apparatus shown in FIG. It is a schematic diagram for demonstrating the drive method of the θ-axis direction of the optical head part by the tilt control part in the laser irradiation apparatus shown in FIG. It is a figure which shows typically the example of the drive means of the optical head part in the laser irradiation apparatus shown in FIG. It is a schematic diagram for demonstrating the drive method of the θ-axis direction of the optical head part by the tilt control part in the laser irradiation apparatus shown in FIG. It is a figure which shows roughly the principle of the autofocus control mechanism in the conventional laser irradiation apparatus. It is a figure which shows roughly the structure of the laser irradiation apparatus which does not need to provide the optical path for focus control different from the optical system for irradiation which the present inventors devised. It is a figure which shows the waveform of signal MONC output from the detector of AF optical system in the laser irradiation apparatus shown in FIG.

  Hereinafter, a laser irradiation apparatus having a tilt control mechanism as a best mode for carrying out a laser irradiation apparatus having a tilt control mechanism and a tilt control method in the laser irradiation apparatus of the present invention will be described in detail with reference to the accompanying drawings. To do. 1 to 8 are diagrams illustrating embodiments of the present invention. In these drawings, the same reference numerals denote the same components, and the basic configuration and operation are the same. To do.

[Constitution]
FIG. 1 is a diagram schematically showing the overall configuration of the laser irradiation apparatus of the present embodiment.
In FIG. 1, the laser irradiation apparatus of this embodiment is
(A) laser light emitting units 6a to 6d having a semiconductor laser element that emits a laser beam and a coupling lens (not shown);
(B) an optical fiber group 2a into which the laser beam emitted from each of the laser emitting units 6a and 6b is incident at one end;
(C) an optical fiber group 2b into which laser beams emitted from the laser light emitting units 6c and 6d are incident at one end;
(D) A plurality of laser beams emitted from the other end of each of the optical fiber groups 2a and 2b are incident on one side surface, and a pair of light guide plates 13a are emitted from the other side surface while irregularly reflecting the laser beam inside. 13b,
(E) a collimating lens 14 that converts the laser beam emitted from each of the light guide plates 13a and 13b into parallel light in the same direction;
(F) an objective lens 16 that condenses the laser beam, which is parallel light emitted from the collimator lens 14, and irradiates the irradiation target 20;
(G) a pair of return optical fibers 5a, 5b for guiding the laser beam reflected from the irradiation object 20 and incident on the light guide plates 13a, 13b to the outside from a substantially central portion of one side surface of each of the light guide plates 13a, 13b; ,
(H) an AF optical system L (31) and an AF optical system R (32) into which a laser beam emitted from the other end of each of the return optical fibers 5a and 5b is incident;
(I) an AF control unit 35 that outputs a control signal for controlling the driving of the objective lens 16 based on signals output from the AF optical system L (31) and the AF optical system R (32);
(J) Based on the signals output from the AF optical system L (31) and the AF optical system R (32), a control signal for controlling the driving of the optical head unit 80 to the driving means (not shown). Output tilt control unit 40
It consists of.

  In the laser irradiation apparatus of the present embodiment, the laser light emitting units 6a to 6d, the optical fiber groups 2a and 2b, the collimator lens 14, the objective lens 16, the return optical fibers 5a and 5b, the AF optical system L (31), and the AF optical system R About (32), it shall be comprised similarly to the component in the conventional laser irradiation apparatus shown in FIG. Further, the AF optical system L (31) and the AF optical system R (32) have the same AF condensing lens and detector as shown in FIG.

  In the laser irradiation apparatus of this embodiment, as shown in FIG. 1, the light guide plates 13a and 13b are substantially the same flat plate shape, and are symmetrical with respect to the optical axis of the irradiation light. The emission direction of the laser beam is adjusted so that approximately the same amount of laser beam emitted from the side surface of the other end enters the collimator lens 14, but otherwise, the conventional method shown in FIG. 10 is used. This is the same as the collimating lens 14 in the laser irradiation apparatus.

  In the laser irradiation apparatus of the present embodiment, as shown in FIG. 1, the AF control unit 35 is configured to perform an objective based on signals from the two systems output from the AF optical system L (31) and the AF optical system R (32). The driving of the lens 16 is controlled (details will be described later), but the rest is the same as the AF control unit 35 in the conventional laser irradiation apparatus shown in FIG.

Although not shown, the laser irradiation apparatus of the present embodiment moves the optical head unit 80 in an arc shape so that the irradiation direction changes while maintaining a certain distance from the irradiation point on the irradiation surface of the irradiation target 20. It has drive means (θ-axis direction).
Further, the laser irradiation apparatus of the present embodiment is a driving unit that moves the optical head unit 80 in a direction perpendicular to the irradiation surface of the irradiation target 20 (Z-axis direction) and in one direction parallel to the irradiation surface (Y-axis direction). You may have.

[Operation]
In the laser irradiation apparatus of the present embodiment, the principle of operation for performing focusing and tilt control using a focus control optical system will be described.

FIG. 2 is a schematic diagram for explaining a variation (tilt) of an irradiation target generated in the laser irradiation apparatus of the present embodiment and a countermeasure for the same.
In general, an irradiation target in a laser irradiation apparatus for laser annealing is a glass substrate having a silicon film formed on the upper surface, but the surface (irradiation surface) has a thickness depending on the state of the glass substrate surface and the film formation state of silicon. Unevenness in the thickness is inevitable, and in some cases, the height of the irradiated surface may vary by 20 to 30 μm.

  As shown in FIG. 2A, when the irradiation surface of the irradiation object is tilted, the focal depth of the laser beam used in the laser irradiation apparatus of the present embodiment may be extremely shallow. Can not be uniformly irradiated. This cannot be dealt with by the focus adjustment by the objective lens in the conventional laser irradiation apparatus shown in FIGS. Therefore, as shown in FIG. 2A, the irradiation direction (optical axis direction) must be adjusted according to the inclination of the irradiation surface.

  As described above, the laser irradiation apparatus of the present embodiment has a pair of irradiation optical system and focus control optical system, and each irradiation light is determined based on the positional relationship between the light guide plates 13a and 13b and the collimating lens 14. Is asymmetric in the vertical direction in FIG. In FIG. 1, the laser spot 7 on the irradiation object 20 is represented as a point, but actually, as shown in FIG. 3, a spot shape (typically having a certain width in the direction substantially perpendicular to the scanning direction) In this case, an elliptical laser spot is irradiated. The light guide plates 13a and 13b and the collimating lens 14 are arranged so that the irradiation light from the pair of irradiation optical systems is asymmetric in the width direction of the laser spot. As a result, the return light incident on the pair of AF optical systems L (31) and R (32) also has the same asymmetry.

  Therefore, the tilt control unit 40 can obtain an optimum irradiation direction based on signals from the AF optical system L (31) and the AF optical system R (32). For example, the θ-axis direction of the optical head unit 80 is set so that the combined signal obtained by adding the signals MONL and MONR output from the AF optical system L (31) and the AF optical system R (32) takes a maximum value. What is necessary is just to control a drive. FIG. 4 is a diagram illustrating the waveform of the combined signal MONL + MONR of each signal output from the pair of AF optical systems. Actually, as shown in FIG. 4, control may be performed so that the value of the combined signal MONL + MONR exceeds a predetermined threshold value Vt (for example, 90% of the maximum output level value).

Here, the driving method of the optical head unit 80 in the θ-axis direction by the tilt control unit 40 is as shown in FIG. 5B, assuming that the approximate center of the optical head unit 80 is the rotation axis as shown in FIG. As shown, the focus position shifts. Therefore, as shown in FIGS. 6A and 6B, the tilt control unit 40 performs drive control so that the optical head unit 80 rotates in the θ direction with the focal point on the irradiation surface of the irradiation object as the rotation axis.
As the driving means for rotating the optical head unit 80 in the θ-axis direction in this way, for example, a method of holding the optical head unit 80 on a stage as shown in FIG. 7 is suitable.

  Furthermore, in the laser irradiation apparatus of the present embodiment, the driving unit moves the optical head unit 80 in a direction perpendicular to the irradiation surface of the irradiation target 20 (Z-axis direction) and in one direction parallel to the irradiation surface (Y-axis direction). 8, the tilt control unit 40 drives the optical head unit 80 in the Y-axis, Z-axis, and θ-axis directions, respectively, as shown in FIGS. 8 (a), 8 (b), and 8 (c). Thus, it is possible to adjust the focal position shift. In this case, it is preferable to obtain and store in advance the relationship between the amount of focal position shift and tilt and the amount of movement in the Y-axis, Z-axis, and θ-axis directions.

The method of performing tilt control using the focus control optical system described above can be similarly applied to focus control by the AF control unit 35. That is, by driving and controlling the objective lens 16 so that the combined signal obtained by adding the signals MONL and MONR output from each of the AF optical system L (31) and the AF optical system R (32) takes a maximum value, Focusing can be suitably performed.
Note that the focus control method in the laser irradiation apparatus of the present embodiment is not limited to the above example. For example, the AF optical system L (31) and the AF optical system R (32) have a focus error caused by the astigmatism method. A signal may be output, and the AF control unit 35 may control the objective lens 16 based on the focus error signal.

The laser irradiation apparatus having the tilt control mechanism and the tilt control method in the laser irradiation apparatus according to the present invention have been described with reference to specific embodiments, but the present invention is not limited to these. A person skilled in the art can make various changes and improvements to the configurations and functions of the optical system, detector, focus control system, tilt control system, etc. in the above embodiments without departing from the scope of the present invention. It is.
For example, in the laser irradiation apparatus according to the above-described embodiment, a pair of AF optical systems that receive the return light from the irradiation target 20 are provided. However, the present invention is not limited to this configuration, and any even number of AF optical systems is provided. It may be provided.
In the laser irradiation apparatus according to the above-described embodiment, the semiconductor laser element is used. However, other types of light sources can be used as a matter of course.

  The laser irradiation apparatus having the tilt control mechanism of the present invention and the tilt control method in the laser irradiation apparatus can be implemented in a laser annealing apparatus that modifies a silicon film formed on the surface of an irradiation target, and includes a phase change optical disk, a flat It can be used in the manufacturing process of panel displays, solar cells and the like.

1a, 1b,..., 1n Semiconductor laser elements 2, 2a, 2b Optical fibers 4a, 4b Coupling lenses 5, 5a, 5b Optical fibers 6a, 6b, 6c, 6d Laser light emitting part 7 Laser spot 10 Optical head part 11 Detector 12 Condensing lens 13, 13a, 13b Light guide plate 14 Collimating lens 16 Objective lens 17 Return light 20 Irradiation target 30 AF optical system 35 AF control unit 40 Tilt control unit 70, 80 Optical head unit

Claims (14)

A laser irradiation apparatus that irradiates a laser spot that focuses laser light on an irradiation object,
A plurality of irradiation optical systems comprising means for emitting laser light;
A collimating lens that receives laser light emitted from each of the irradiation optical systems and collects the collimated light;
An objective lens that focuses the laser light that has passed through the collimating lens into a predetermined laser spot shape and focuses on the irradiation surface of the irradiation target;
A plurality of return optical systems that receive the return light that is reflected by the laser light applied to the irradiation object and passes through the objective lens and the collimator lens;
Means for detecting the amount of return light received in each of the return optical systems;
The laser irradiation apparatus which has an irradiation direction adjustment means which adjusts the irradiation direction of the laser spot with respect to an irradiation target based on the detected light quantity of the return light.   The laser irradiation apparatus according to claim 1, wherein the irradiation direction adjusting unit adjusts the irradiation direction of the laser spot while fixing a focal point on the irradiation surface of the irradiation object. In the laser irradiation apparatus, the laser irradiation device has an optical head portion that houses the collimating lens and the objective lens,
The irradiation direction adjusting means adjusts the irradiation direction of the laser spot by turning the optical head unit around the central axis with the focal point on the irradiation surface of the irradiation object as the central axis. The laser irradiation apparatus according to claim 2.   The irradiation direction adjusting means adjusts the irradiation position on the irradiation object by adjusting the position of the optical head in a direction parallel to and perpendicular to the irradiation surface of the irradiation object. 3. The laser irradiation apparatus according to 3.   The irradiation direction adjusting unit is configured to adjust the irradiation direction of the laser spot and / or the irradiation position on the irradiation target so that the total value of the amount of return light received by each of the return optical systems becomes a maximum value. The laser irradiation apparatus according to claim 1, wherein the laser irradiation apparatus is adjusted.   The irradiation direction adjusting means is configured to apply the laser spot irradiation direction to the irradiation target and / or on the irradiation target so that the total amount of the return light received by each of the return optical systems is equal to or greater than a predetermined threshold value. The laser irradiation apparatus according to claim 1, wherein an irradiation position is adjusted.   In the laser irradiation apparatus, a focal point for focusing the laser spot on the irradiation target by moving the objective lens in a direction substantially perpendicular to the irradiation surface of the irradiation target based on the amount of the detected return light. The laser irradiation apparatus according to claim 1, further comprising an adjusting unit. A plurality of irradiation optical systems having means for emitting laser light; a collimating lens that receives the laser light emitted from each of the irradiation optical systems and collects the collimated light; and predetermined laser light that has passed through the collimating lens. An objective lens that focuses on the laser spot shape and focuses on the irradiation surface of the irradiation target, and the return light that is reflected by the laser light irradiated on the irradiation target and passes through the objective lens and the collimating lens. In a laser irradiation apparatus having a plurality of return optical systems that receive light and means for detecting the amount of return light received by each of the return optical systems,
A laser irradiation method comprising adjusting an irradiation direction of a laser spot on an irradiation object based on the detected amount of return light.   9. The laser irradiation method according to claim 8, wherein the irradiation direction of the laser spot is adjusted while fixing the focal point on the irradiation surface of the irradiation object. In the laser irradiation apparatus, the laser irradiation device has an optical head portion that houses the collimating lens and the objective lens,
10. The laser according to claim 9, wherein the irradiation direction of the laser spot is adjusted by rotating the optical head around the central axis with the focal point on the irradiation surface of the irradiation object as the central axis. Irradiation method.   The laser irradiation method according to claim 10, wherein the irradiation position on the irradiation object is adjusted by adjusting the position of the optical head in a direction parallel to and perpendicular to an irradiation surface of the irradiation object. .   The irradiation direction of the laser spot with respect to the irradiation object and / or the irradiation position on the irradiation object is adjusted so that the total value of the amount of the return light received in each of the return optical systems becomes the maximum value. The laser irradiation method according to any one of claims 8 to 11.   Adjusting the irradiation direction of the laser spot on the irradiation object and / or the irradiation position on the irradiation object such that the total amount of the return light received by each of the return optical systems is equal to or greater than a predetermined threshold value. The laser irradiation method according to any one of claims 8 to 11, wherein the laser irradiation method is characterized in that:   The laser spot is focused on the irradiation object by moving the objective lens in a direction substantially perpendicular to the irradiation surface of the irradiation object based on the amount of the detected return light. 14. The laser irradiation method according to any one of 8 to 13.