JP4999546B2 - Laser beam intensity pattern forming device - Google Patents

Description

  The present invention relates to a laser beam intensity pattern forming apparatus which is applied to an apparatus having a function of arbitrarily forming an intensity pattern of a laser beam, such as a laser processing machine, and which controls the intensity pattern by a spatial phase modulator. .

  2. Description of the Related Art Laser processing machines that perform processing such as irradiating an object with a laser beam and making a hole in a portion irradiated with the laser beam are generally used. In such a laser processing machine, in order to engrave an object in an arbitrary pattern, an apparatus has been developed that irradiates a laser beam intensity pattern that matches the engraved pattern without scanning the laser beam in a time-sharing manner. (For example, refer to Patent Document 1). In the laser processing machine disclosed in Patent Document 1, the spatial phase distribution of the laser beam is formed into a predetermined shape with a reflective spatial light modulator in order to increase the energy efficiency used for processing the laser beam, and the electric field is further increased. An arbitrary intensity pattern is formed by performing a Fourier transform with a Fourier transform lens.

JP 2001-272635 A (FIG. 1)

In the conventional laser beam intensity pattern forming apparatus, the spatial phase distribution of the laser beam is appropriately converted as described above, and the electric field of the laser beam converted from the spatial phase distribution is further Fourier transformed by a Fourier transform lens. Although it is possible to form the laser beam intensity pattern, there are the following problems.
First, as a method for determining the spatial phase distribution of the laser beam converted by the spatial light modulator, the same calculation as that of a generally known computer hologram design method (simulated annealing method) was performed by electronic calculation. In this method, it is necessary to repeatedly perform calculation for obtaining an intensity pattern formed on a workpiece by two-dimensional Fourier transform of an electric field of a laser beam obtained by converting a spatial phase distribution by a spatial light modulator. Accordingly, it takes a considerable amount of time until the phase distribution conversion amount of the spatial light modulator for realizing the intensity pattern to be formed is obtained. Therefore, practically, it is necessary to calculate the phase conversion amount of the spatial light modulator corresponding to a specific processing pattern in advance and store it in the storage device, and read it from the storage device as necessary. That is, it is not possible to form an intensity pattern other than a predetermined one, and it is impossible to cope with a request for correction during processing.
Secondly, in the spatial light modulator, if there is a phase conversion error due to the limit of phase conversion resolution or a change with time, there is a difference between the calculated desired intensity pattern and the actually formed intensity pattern. Though possible, there is no way to correct this.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a laser beam intensity pattern forming apparatus capable of calculating in a short time the phase conversion amount of a laser beam converted by a spatial light modulator. And

  A laser beam intensity pattern forming apparatus according to the present invention includes a first laser light source that generates a laser beam and a first phase that converts a spatial phase distribution of the laser beam from the first laser light source in accordance with phase control information. A conversion unit, a first Fourier conversion unit that optically Fourier-transforms and outputs the laser beam converted by the first phase conversion unit, and a space for calculating a spatial phase distribution converted by the first phase conversion unit A laser beam intensity pattern forming apparatus including an optical phase distribution calculation unit, wherein the spatial light phase distribution calculation unit includes a second laser light source that generates a laser beam, and a second laser light source according to phase control information. A second phase converting means for converting the spatial phase distribution of the laser beam of the laser beam, and a second phase optically Fourier transforming the laser beam converted by the second phase converting means. A first phase detection means for detecting the spatial phase distribution of the laser beam converted by the second Fourier transform means, a third laser light source for generating the laser beam, Intensity conversion means for converting the spatial intensity distribution of the laser beam from the third laser light source based on the intensity pattern, and the spatial phase distribution of the laser beam converted by the intensity conversion means are detected by the first phase detection means. A third phase conversion unit that converts the spatial phase distribution according to the spatial phase distribution, an inverse Fourier transform unit that optically performs an inverse Fourier transform on the laser beam converted by the third phase conversion unit, and an inverse Fourier transform unit. A second phase detector for detecting the spatial phase distribution of the laser beam, and a second phase change using the spatial phase distribution detected by the second phase detector as phase control information. Those having a calculation loop and a phase control means for providing means and to the first phase converter.

  According to the present invention, it is possible to perform complex and time-consuming repetitive calculations at high speed by providing a spatial phase distribution calculation unit and applying a Fourier transform lens that is an optical transformation process to the IFTA (Iterative Fourier Transform Algorithm) method. Is possible. Therefore, it is possible to form the required intensity pattern in a short time even in response to an intensity pattern formation request other than the default, which is impossible with the conventional laser beam intensity pattern forming apparatus.

Embodiment 1 FIG.
1 is a block diagram showing a functional configuration of a laser beam intensity pattern forming apparatus according to Embodiment 1 of the present invention. In FIG. 1, each part shown as the 1st laser light source 1, the 1st phase conversion means 5, the 1st Fourier-transform means 6, and the process target object 7 is the same as that of the conventional laser processing machine of patent document 1 It has a function.
The first laser light source 1 includes a laser oscillator 2, a concave lens 3, and a convex lens 4, and a laser beam emitted from the laser oscillator 2 to the space is expanded to a predetermined aperture by the concave lens 3 and the convex lens 4. The laser beam emitted from the laser light source 1 to the space propagates in the space with a substantially planar phase distribution and enters the first phase conversion means 5. The first phase conversion means 5 is a reflective spatial light modulator that arbitrarily forms only the spatial phase distribution without converting the intensity of the laser beam. For example, the optical writing type liquid crystal disclosed in Patent Document 1 is used. Realized by the commercial product used. The laser beam whose spatial phase distribution has been converted by the first phase converting means 5 enters the first Fourier transform means 6. The first Fourier transform means 6 is, for example, a glass refractive convex lens, but may be a reflective concave mirror. The first phase converting means 5 is located at the front focal point of the first Fourier transforming means 6, and the workpiece 7 is placed at the rear focal point of the first Fourier transforming means 6. As is generally known, the electric field of the light wave at the front focal point of the convex lens and the electric field of the light wave at the rear focal point after focusing have a Fourier transform relationship. That is, an intensity pattern obtained by Fourier transforming the electric field of the laser beam having a spatial phase distribution formed by the first phase conversion means 5 is formed on the workpiece 7.

The first embodiment includes a spatial phase distribution calculation unit 10 for realizing the present invention. The spatial phase distribution calculation unit 10 has a function of calculating the spatial phase distribution of the electric field of the laser beam formed by the first phase conversion means 5 at high speed in order to form a desired intensity pattern on the workpiece 7. Have
The spatial phase distribution calculation unit 10 according to the first embodiment includes a second laser light source 20, a second phase conversion unit 21, a second Fourier transform unit 23, and a first phase detection unit 24. Among these, the second laser light source 20, the second phase conversion means 21, and the second Fourier transform means 23 are the first laser light source 1, the first phase conversion means 5, and the first, respectively. The same functions as those of the Fourier transform means 6 are provided, and the mutual replacement relation is formed in the same manner. With this configuration, if the spatial phase distribution of the laser beam formed by the second phase conversion unit 21 is controlled so as to be equal to the spatial phase distribution of the laser beam formed by the first phase conversion unit 5. An electric field equivalent to the electric field of the laser beam on the workpiece 7 is formed in the spatial light phase distribution calculation unit 10. The first phase detection unit 24 is a unit that is placed on the back focal plane of the second Fourier transform unit 23 and detects the spatial phase distribution of the electric field of the laser beam converted by the second Fourier transform unit 23. For example, it is composed of an interferometer that splits a light wave into two light beams, converts one light beam into a substantially plane wave by a spatial filter, and then combines and interferes again to detect the spatial phase distribution of the light wave from the interference intensity distribution.

The spatial phase distribution calculation unit 10 further includes a third laser light source 30, an intensity conversion unit 31, a third phase conversion unit 32, an inverse Fourier transform unit 33, a second phase detection unit 34, a second control unit 35, A third control means 36 and a first control means (phase control means) 37 are provided.
The third laser light source 30 is also a light source having a function equivalent to that of the first laser light source 1. The intensity conversion means 31 is constituted by a spatial light modulator, and is a means for converting the spatial intensity distribution of the laser beam from the third laser light source 30 based on a desired intensity pattern prepared in advance. The third phase conversion means 32 is a spatial light modulator similar to the first phase conversion means 5 and the second phase conversion means 21, and the laser beam of the third laser light source 30 converted by the intensity conversion means. It is means for converting the spatial phase distribution according to the spatial phase distribution detected by the first phase detection means. The laser beam emitted from the third laser light source 30 to the space is a substantially plane wave, but has an electric field composed of a certain spatial intensity distribution and spatial phase distribution by the intensity conversion means 31 and the third phase conversion means 32. It is converted into a laser beam. The inverse Fourier transform unit 33 is a convex lens similar to the first Fourier transform unit 6 and the second Fourier transform unit 23, and optically reverses the electric field of the laser beam converted by the third phase conversion unit 32. It is a means for Fourier transform. The second phase detection unit 34 has a function equivalent to that of the first phase detection unit 24 and is a unit that detects the spatial phase distribution of the laser beam converted by the inverse Fourier transform unit 33.

The third controller 36 adjusts the third phase so that the spatial phase distribution of the laser beam formed by the third phase converter 32 matches the spatial phase distribution of the laser beam detected by the first phase detector 24. It is means for controlling the phase conversion means 32. Therefore, the first phase detection unit 24 converts the detected spatial phase distribution information into an electrical signal and provides it to the third control unit 36. The second control means 35 is means for controlling the intensity conversion means 31 so as to convert the spatial intensity distribution of the laser beam of the third laser light source based on a desired intensity pattern given in advance. The first control unit 37 is a unit that gives the spatial phase distribution of the laser beam detected by the second phase detection unit 34 to the second phase conversion unit 21 as phase control information. The first control unit 37 also has a function of giving phase control information to the first phase conversion unit 5 at an appropriate time point for the calculation by the spatial light phase distribution calculation unit 10.
The configuration of the spatial phase distribution calculation unit 10 described above forms a calculation loop that calculates the spatial phase distribution of the electric field of the laser beam formed by the first phase conversion means 5 at high speed.

Next, the operation of the spatial phase distribution calculation unit 10 will be described.
The spatial phase distribution calculation unit 10 calculates the phase conversion amount converted by the first phase conversion means 5 by applying IFTA, which is one of the generally known kinoform-type Computer Generated Hologram design techniques. . FIG. 2 is a flowchart showing a processing procedure for calculating the phase conversion amount converted by the first phase conversion means 5 in the spatial phase distribution calculation unit 10.
When a desired intensity pattern to be formed on the workpiece 7 is set in the second control means 35, the pattern control information is given to the intensity conversion means 31 (step ST201). Based on this control information, the intensity conversion means 31 modulates the intensity (amplitude) of the light wave of the laser beam output from the third laser light source 30 so as to match the desired intensity pattern (step ST202). Next, the phase of the light wave of the laser beam whose spatial intensity distribution is converted is modulated by the third phase conversion means 32 controlled as described later by the third control means 36 (step ST203), and the light wave A is changed. Obtain (step ST204). In this case, the initial value is determined by a random number, for example. Next, the light wave A whose intensity and phase are determined is subjected to inverse Fourier transform by the inverse Fourier transform means 33 (step ST205) to obtain a light wave B (step ST206).

The second phase detection means 34 detects the phase of the light wave B after the inverse Fourier change and provides it to the first control means 37 (step ST207). The first control means 37 controls the second phase conversion means 21 based on the detected phase of the light wave B, modulates the phase of the laser beam of the second laser light source 20 (step ST210), and In combination with the fixed intensity (step ST209), the light wave C is formed (step ST211). Next, the second Fourier transform means 23 performs Fourier transform on the light wave C (step ST212) to form a light wave D (step ST213). Next, the first phase detection means 24 detects the phase of the formed light wave D (step ST214), and the detected phase, that is, information on the spatial phase distribution is converted into an electrical signal, and the third control means 36 is used. Given to. The third control means 36 controls the third phase conversion means 32 based on the information on the spatial phase distribution of the light wave D, and modulates the light wave A so as to have the same spatial phase distribution as the light wave D (step ST203). .
The above processing procedure represents one cycle of the arithmetic processing performed by the calculation loop. By repeating this processing a plurality of cycles, the phase of the light wave D gradually changes, and the intensity of the light wave D becomes the intensity of the light wave A, that is, the desired intensity. Approaching the pattern.

  FIG. 3 shows an example of a result of simulation of the present algorithm by an electronic computer. FIG. 3A shows the desired intensity pattern set in step ST201. FIG. 3B shows the intensity of the light wave D obtained in the first processing procedure, and FIG. 3C shows the intensity of the light wave D obtained in the 90th processing procedure. As apparent from FIG. 3, it can be seen that the intensity of the light wave D approaches the desired intensity pattern FIG. 3A by repeating the processing procedure.

  As described above, it can be understood that the spatial phase distribution to be converted by the first phase conversion means 5 is obtained by repeating the processing cycle of the calculation loop shown in FIG. It is to calculate the distribution at high speed. That is, it is necessary to reduce the number of processing cycles as much as possible to obtain the required spatial phase distribution. For this reason, in the present invention, processing for determining whether the spatial phase distribution achieves a desired intensity pattern is performed every processing cycle. This determination process may be realized in an electronic computer (not shown) that controls the means of the spatial phase distribution calculation unit 10 in an integrated manner. Therefore, the electronic computer performs the processing procedure shown in FIG. 2 so that the second control unit 35, the third control unit 36, the first control unit 37, the first phase detection unit 24, and the second phase are performed. A control command for operating according to a sequence programmed in advance is given to the detection means 34. In addition, the electronic computer continues to store the spatial phase distribution detected by the second phase detection unit 34 in the storage device every time the processing cycle is repeated, and creates a time-series change history. Furthermore, the time series change history of the spatial phase distribution is constantly evaluated, it is determined that the spatial phase distribution has not changed even after repeated processing cycles, and has converged to a constant value, and a control command is issued to the first control means 37. Then, the processing is interrupted so that the phase control amount of the first phase conversion means 5 is output to the phase control information so as to match the converged spatial phase distribution.

  For example, Frank Wyrowski and Olof Bryngdahl, “Iterative Fourier-transform algorithm applied computer holography”, J. Opt. Soc. Am. A, Vol. 5, p1058, 1988 It is generally known that it is effective. However, the first embodiment differs from the above document in that Fourier transform and inverse Fourier transform are performed by a Fourier transform lens that is an optical process.

  As described above, according to the first embodiment, by providing the spatial phase distribution calculation unit 10 and applying the Fourier transform lens, which is an optical conversion process, to the IFTA method, it is possible to perform complex and time-consuming repetitive calculations at high speed. It becomes possible to do in. Therefore, it is possible to form the required intensity pattern in a short time even in response to an intensity pattern formation request other than the default, which is impossible with the conventional laser beam intensity pattern forming apparatus. In the case of the first embodiment, the optical conversion process is performed using the second and third laser light sources 20 and 30 without using the energy emitted by the first laser light source 1. The energy efficiency of the first laser light source 1 is not impaired.

Embodiment 2. FIG.
4 is a block diagram showing a functional configuration of a laser beam intensity pattern forming apparatus according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote equivalent functional parts, and the description thereof will be omitted in principle. In the second embodiment, instead of the second laser light source 20 and the second phase conversion means 21 of the first embodiment, the optical path bends between the first phase conversion means 5 and the first Fourier transform means 6. Means 100 is arranged, and the first laser light source 1 is also used as the second laser light source 20.
The optical path bending means 100 is a means for bending the optical path of the laser beam from the first laser light source 1 converted by the first phase conversion means 5, and is composed of, for example, a plane mirror polished on a plane with high accuracy, and is a laser. Reflection is possible without changing the intensity and phase distribution of the beam. In addition, the plane mirror which is the optical path bending means 100 can be selected from two types of arrangements in which the laser beam converted by the first phase conversion means 5 is bent and when it is not bent by driving and controlling the use position. I have to. That is, in FIG. 4, 100 (a) represents an arrangement when the laser beam is bent, and 100 (b) represents an arrangement when the laser beam is not bent.

Next, the operation will be described.
Now, when the optical path bending means 100 is at the position of 100 (a), the bent laser beam goes to the second Fourier transform means 23. That is, the first laser light source 1 acts in the same manner as the second laser light source 20 in FIG. 1, and the first phase conversion means 5 acts in the same manner as the second phase conversion means 21 in FIG. Become. In this state, the spatial light phase distribution calculation unit 10 of the second embodiment can perform the same calculation as that of the first embodiment. Next, when an electronic computer (not shown) determines that the spatial phase distribution of the first phase conversion unit 5 is suitable for forming a desired intensity pattern, the first control unit 36 converts the spatial phase distribution with the first phase conversion unit 5. The spatial phase distribution of the laser beam to be fixed is fixed, and the optical path bending means 100 is switched to the position 100 (b). Then, since the laser beam converted by the first phase conversion unit 5 is not bent, it is Fourier-transformed by the first Fourier transform unit 6 to form a desired intensity pattern on the workpiece 7.

  As described above, according to the second embodiment, the first laser light source 1 and the first phase conversion means 5 are used not only for processing the workpiece 7 but also for the optical signal processing in the spatial phase distribution calculation unit 10. Therefore, it is possible to reduce the size and weight of the device, save power, and reduce the manufacturing cost. In addition, with the configuration of the second embodiment, since the calculation of the spatial phase distribution of the first phase conversion unit 5 is completed and the drive control of the first phase conversion unit 5 is completed, the control delay is reduced. It can be shortened. Furthermore, since the control of the first phase conversion means 5 is performed in a closed loop, the control accuracy can be improved.

  In the above example, the laser beam is bent using a plane mirror that drives and controls the position as the optical path bending means 100. Instead of the plane mirror, means that can deflect or branch the laser beam in two directions are used. Obviously, the operation of the second embodiment can be satisfied. For example, a beam splitter may be used for the optical path bending means 100 to split the laser beam into two. However, in this case, the workpiece 7 is always irradiated with the laser beam. However, if the automatic stage is retracted until the control of the first phase conversion means 5 is completed, the function is impaired. The same effect can be expected.

Embodiment 3 FIG.
FIG. 5 is a block diagram showing a functional configuration of a laser beam intensity pattern forming apparatus according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG. 4 denote equivalent functional parts, and the description thereof will be omitted in principle. In the third embodiment, intensity detecting means 110 is provided to the second embodiment to improve the second embodiment.
The intensity detection unit 110 is a unit that detects the intensity of the light wave converted by the second Fourier transform unit 23.

Next, the operation will be described.
FIG. 6 is a flowchart showing a processing procedure for calculating the phase conversion amount converted by the first phase conversion means 5 in the spatial phase distribution calculation unit 10 of the third embodiment. In the figure, the same processing step codes as those in FIG. 2 indicate equivalent processes, and the description thereof is omitted. In the case of the third embodiment, steps ST215 and ST217 are added to the processing of the first embodiment.
The intensity detection means 110 detects the intensity of the light wave D converted by the second Fourier transform means 23 and provides it to the first control means 37 (step ST215). The first control means 37 estimates the phase of the light wave C from the intensity of the light wave D detected by the intensity detection means 110, and the light wave C detected by the second phase detection means 34 in step ST207. The difference from the phase of B is calculated, and the phase modulation amount performed by the first phase conversion means 5 in the process of step ST210 is corrected according to the difference (step ST217).

  As described above, according to the third embodiment, by providing the intensity detection unit 110, the phase detected by the first phase detection unit 24 and the phase modulation amount converted by the first phase conversion unit 5 can be obtained. Therefore, even when the first phase conversion means 5 has a driving error such as hysteresis, desired laser beam intensity pattern control can be performed with high accuracy. Further, in the interrupt processing of the iterative loop calculation in an electronic computer (not shown), the spatial intensity distribution detected by the second intensity detecting means 31 and the desired intensity pattern are directly compared, so that the control accuracy can be improved. It becomes.

Embodiment 4 FIG.
FIG. 7 is a block diagram showing a functional configuration of a laser beam intensity pattern forming apparatus according to Embodiment 4 of the present invention. In the figure, the same reference numerals as those in FIG. 4 denote equivalent functional parts, and the description thereof will be omitted in principle. In the fourth embodiment, an optical wave branching unit 120 and a third phase detection unit 121 are provided between the optical path bending unit 100 and the second Fourier transform unit 23 of the second embodiment, and the second embodiment is improved. It has become.
The light wave branching unit 120 is a unit that extracts the laser beam converted by the first phase conversion unit 5 by dividing the amplitude. The third phase detection unit 121 is a unit that detects the spatial phase distribution of the laser beam converted by the first phase conversion unit 5 branched and extracted by the light wave branching unit 120.

Next, the operation will be described.
FIG. 8 is a flowchart showing a processing procedure for calculating the phase conversion amount converted by the first phase conversion means 5 in the spatial phase distribution calculation unit 10 of the fourth embodiment. In the figure, the same processing step codes as those in FIG. 2 indicate equivalent processes, and the description thereof is omitted. In the case of the fourth embodiment, the processes of step ST217 and step ST218 are added to the process of the third embodiment.
The laser beam (light wave C) converted by the first phase converting means 5 is extracted by dividing the amplitude by the light wave branching means 120, and the phase of the extracted light wave C is detected by the third phase detecting means 121. It outputs to the 1st control means 37 (step ST218). The first control unit 37 calculates the difference between the phase of the given light wave C and the phase of the light wave B detected by the second phase detection unit 34, and the first phase conversion unit 5 determines the difference according to the difference. The amount of phase modulation performed in step ST210 is corrected (step ST217).

  As described above, according to the fourth embodiment, the phase detected by the first phase detection unit 24 and the first phase conversion are provided by providing the light wave branching unit 120 and the third phase detection unit 121. Since the difference from the phase modulation amount converted by the means 5 can be corrected, the desired antenna beam intensity pattern control can be accurately performed even when the first phase conversion means 5 has a driving error such as hysteresis, as in the third embodiment. Is possible.

It is a block diagram which shows the function structure of the laser beam intensity pattern formation apparatus by Embodiment 1 of this invention. It is a flowchart which shows the process sequence of the spatial phase distribution calculating part which concerns on Embodiment 1 of this invention. It is explanatory drawing which compares the simulation result of the light wave intensity pattern in the process by Embodiment 1 of this invention. It is a block diagram which shows the function structure of the laser beam intensity | strength pattern formation apparatus by Embodiment 2 of this invention. It is a block diagram which shows the function structure of the laser beam intensity | strength pattern formation apparatus by Embodiment 3 of this invention. It is a flowchart which shows the process sequence of the spatial phase distribution calculating part which concerns on Embodiment 3 of this invention. It is a block diagram which shows the function structure of the laser beam intensity | strength pattern formation apparatus by Embodiment 4 of this invention. It is a flowchart which shows the process sequence of the spatial phase distribution calculating part which concerns on Embodiment 4 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 1st laser light source, 2-4 A part of 1st laser light source, 2 Laser oscillator, 3 Concave lens, 4 Convex lens, 5 1st phase conversion means, 6 1st Fourier transform means, 7 Processing object, 10 spatial phase distribution calculation unit, 20 second laser light source, 21 second phase conversion means, 23 second Fourier transform means, 24 first phase detection means, 30 third laser light source, 31 intensity conversion means, 32 Third phase conversion means, 33 Inverse Fourier transform means, 34 Second phase detection means, 35 Second control means, 36 Third control means, 37 First control means (phase control means), 100 Optical path Bending means, 110 intensity detecting means, 120 light wave branching means, 121 third phase detecting means.

Claims (6)

A first laser light source for generating a laser beam;
First phase conversion means for converting a spatial phase distribution of a laser beam from the first laser light source according to phase control information;
First Fourier transform means for optically Fourier transforming and outputting the laser beam converted by the first phase conversion means;
A laser beam intensity pattern forming device including a spatial light phase distribution calculation unit that calculates a spatial phase distribution converted by the first phase conversion unit,
The spatial light phase distribution calculator is
A second laser light source for generating a laser beam;
Second phase conversion means for converting a spatial phase distribution of a laser beam from the second laser light source according to phase control information;
Second Fourier transform means for optically Fourier transforming the laser beam converted by the second phase conversion means;
First phase detection means for detecting a spatial phase distribution of the laser beam converted by the second Fourier transform means;
A third laser light source for generating a laser beam;
Intensity conversion means for converting the spatial intensity distribution of the laser beam from the third laser light source based on a predetermined intensity pattern given in advance;
Third phase conversion means for converting the spatial phase distribution of the laser beam converted by the intensity conversion means according to the spatial phase distribution detected by the first phase detection means;
Inverse Fourier transform means for optically inverse Fourier transforming the laser beam converted by the third phase conversion means;
Second phase detection means for detecting a spatial phase distribution of the laser beam converted by the inverse Fourier transform means;
A calculation loop including a phase control unit that applies the spatial phase distribution detected by the second phase detection unit to the second phase conversion unit and the first phase conversion unit as the phase control information; A laser beam intensity pattern forming apparatus.   By using the electronic computer, the spatial phase distribution detected by the second phase detection means for each repetitive calculation by the calculation loop is stored in the storage device as a time series change history, and based on the time series change history, Judging that the spatial phase distribution detected by the second phase detection means has converged to a constant value, the spatial phase distribution converted by the first phase conversion means via the phase control means matches the converged spatial phase distribution. 2. The laser beam intensity pattern forming apparatus according to claim 1, wherein: The spatial light phase distribution calculation unit
The first laser light source is also used as the second laser light source, and the first phase conversion means is also used as the second phase conversion means.
Optical path bending means for bending the optical path of the laser beam converted by the first phase conversion means,
3. The laser beam intensity pattern forming apparatus according to claim 1, wherein the second Fourier transform means performs Fourier transform on the laser beam obtained from the optical path bending means. The calculation loop of the spatial light phase distribution calculator is
Intensity detecting means for detecting the spatial intensity distribution of the laser beam converted by the second Fourier transform means,
The control means estimates the spatial phase distribution of the laser beam converted by the first phase conversion means from the spatial intensity distribution detected by the intensity detection means, and the estimated spatial phase distribution and the first phase detection means. The difference between the spatial phase distribution detected in step 1 and the spatial phase distribution detected by the second phase detection means is calculated, and the phase modulation amount of the first phase conversion means is corrected according to the obtained difference. The laser beam intensity pattern forming apparatus according to claim 3. The calculation loop of the spatial light phase distribution calculator is
A third phase detecting means for detecting a spatial phase distribution of the laser beam converted by the first phase converting means;
The phase control means calculates a difference between the spatial phase distribution detected by the first phase detection means and the spatial phase distribution detected by the third phase detection means, and the first control unit calculates the first difference according to the obtained difference. 4. The laser beam intensity pattern forming apparatus according to claim 3, wherein the phase modulation amount of the phase conversion means is corrected.   The optical path bending means takes a position for directing the laser beam converted by the first phase conversion means to the second Fourier transform means when forming a calculation loop of the spatial light phase distribution calculation unit, When the spatial phase distribution of one phase conversion means is in a state suitable for forming a desired intensity pattern, a laser beam converted by the first phase conversion means with a phase modulation amount that matches the spatial phase distribution is 6. The laser beam intensity pattern forming apparatus according to claim 3, wherein the laser beam intensity pattern forming apparatus is configured by a plane mirror that is selectively controlled so as to take a position directed to the first Fourier transform unit.

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