JP2001272634A - Image projection device and image projecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image projection device and an image projecting method capable of projecting an optical image accurately to a target. SOLUTION: The image projection device 10 is provided with a reflection type space optical modulator 20, a hologram pattern writing means 40 for writing a hologram pattern in the reflection type space optical modulator 20, a projection means 50 for being made incident readout light on the reflection type space optical modulator 20 with the prescribed incidence angle θ and a Fourier lens 60 for performing the Fourier transform of the readout light, in which phase modulation is performed by the reflection type space optical modulator 20, and the hologram pattern writing means 40 has a structure where the hologram pattern corresponding to a correction image being made the desired optical image 1/cosθ times in the prescribed direction can be written in the reflection type space optical modulator 20, when the desired optical image is projected on the target T.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image projection apparatus and an image projection method using Fourier transform for performing Fourier transform on light phase-modulated by a spatial light modulator and irradiating an obtained optical image to a target.

[0002]

2. Description of the Related Art There are two types of spatial light modulators widely used in image projection devices, such as an intensity modulation type and a phase modulation type. Particularly, in the field of optical information processing and hologram processing, the latter phase modulation type is used. Is promising. This is because, unlike the intensity modulation type, the phase modulation type spatial light modulator can increase the light use efficiency.

[0003] There are also two types of phase modulation type spatial light modulators, a reflection type and a transmission type. The reflection type is preferably used in order to increase the efficiency of light utilization.

However, in the reflection type spatial light modulator, the plane of incidence of the readout light and the plane of emission of the modulated light are on the same plane, and the modulated light is usually separated from the readout light by using a half mirror. However, the light use efficiency is reduced and the merit of the phase modulation type is lost.

Therefore, the read light is obliquely incident on the incident surface, and the modulated light is extracted by shifting the optical axes of the read light and the modulated light, so that the use of the half mirror is omitted to reduce the light use efficiency. Suppression techniques have been developed.

[0006]

However, in an image projection apparatus that simply uses the above-described conventional technique in which readout light is obliquely incident on an incident surface of a spatial light modulator, an optical image of a target illuminated on a target is read out. There is a problem that the size is larger than the size at the time of design, and the space to be projected is protruded. In particular, in a laser marking device or the like, it is necessary to accurately irradiate a predetermined location with an optical image of a predetermined size to perform marking, and therefore, the protrusion of the optical image has been a serious problem in such a field.

Accordingly, an object of the present invention is to provide an image projection apparatus and an image projection method capable of accurately irradiating an optical image to a target.

[0008]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have made intensive studies on the problem of protrusion of an optical image caused when reading light is obliquely incident on a spatial light modulator. Then, it was found that a distortion corresponding to the incident angle θ of the readout light occurs in the optical image irradiated on the target.

That is, as shown in FIG. 6, when the readout light enters the spatial light modulator at a predetermined incident angle θ and is phase-modulated and reflected by the hologram pattern, the modulated light is cos θ in the width direction. This cos
The optical image obtained by Fourier-transforming the modulated light multiplied by θ is compared with the desired optical image shown in FIG.
As shown in (b), it was found that the image extended in the width direction according to the incident angle θ.

[0010] The present invention has been made based on the above findings. That is, the image projection apparatus of the present invention includes a reflection type spatial light modulator, hologram pattern writing means for writing a hologram pattern on the reflection type spatial light modulator, and a predetermined incident angle θ to the reflection type spatial light modulator. A hologram pattern writing means for projecting a read light into the target; and a Fourier lens for performing a Fourier transform on the read light that has been phase-modulated in the reflection type spatial light modulator. Irradiates the desired optical image in one direction in a predetermined direction.
It has a structure in which a hologram pattern corresponding to a corrected image multiplied by / cos θ can be written in a reflective spatial light modulator.

In this image projection device, the readout light incident on the reflective spatial light modulator at a predetermined incident angle θ is
The light is phase-modulated by the hologram pattern, and is reflected toward the target while containing image information of the hologram pattern. The readout light including the image information of the hologram pattern is distorted and multiplied by cos θ in a predetermined direction.
Since the hologram pattern corresponds to the corrected image multiplied by / cos θ, the effect of the distortion is canceled here. Then, a desired optical image is emitted to a predetermined position of the target by performing Fourier transform on the readout light from which the influence of the distortion has been canceled and forming an image by Fourier transformation.

Further, in the image projection apparatus according to the present invention, the hologram pattern writing means includes a storage means for storing hologram pattern data corresponding to a corrected image previously obtained for a desired optical image. It may be. According to this configuration, the hologram pattern writing unit can write the hologram pattern in the reflection type spatial light modulator only by reading the data of the hologram pattern stored in the storage unit. That is, since it is possible to eliminate the trouble of creating a corrected image from a desired optical image and further creating a hologram pattern,
The hologram pattern can be rewritten at the video rate in the reflective spatial light modulator.

Further, the image projection apparatus of the present invention further comprises an object shape recognizing means for acquiring three-dimensional information of the target, and the hologram pattern writing means comprises a three-dimensional object of the target acquired by the object shape recognizing means. It may have a structure capable of generating a hologram pattern matching the shape of the target based on the information. According to this configuration, the hologram pattern writing unit outputs the target 3 obtained by the object shape recognition unit.
Since it is possible to generate a hologram pattern for forming a pattern three-dimensionally so as to match the shape of the target based on the dimensional information, the possibility that the target is irradiated with a distorted pattern is reduced, and more accurate Image projection can be performed.

Further, the image projection apparatus of the present invention further comprises an object position recognizing means for acquiring position information of the target, and the hologram pattern writing means stores the target position information acquired by the object position recognizing means. A hologram pattern that matches the position of the target based on the hologram pattern.
With this configuration, even when the position of the target on which the image is to be projected is displaced from the desired position, the hologram pattern writing unit sets the target position based on the position information of the target acquired by the object position recognition unit. Since a matched hologram pattern can be generated, accurate image projection can be performed without depending on a change in the position of the target.

The image projection method according to the present invention further comprises a reading light incidence step of causing the reading light to enter the reflection type spatial light modulator at a predetermined incident angle θ, and irradiating a target with a desired optical image. A hologram pattern writing step of creating a hologram pattern corresponding to the corrected image obtained by multiplying the optical image by 1 / cos θ in a predetermined direction and writing the hologram pattern to the reflection type spatial light modulator; And Fourier transforming the modulated readout light to obtain a desired optical image.

In this image projection method, the reading light incident on the reflective spatial light modulator at a predetermined incident angle θ is
The light is phase-modulated by the hologram pattern, and is reflected toward the target while containing image information of the hologram pattern. The readout light including the image information of the hologram pattern is distorted and multiplied by cos θ in a predetermined direction.
Since the hologram pattern corresponds to the corrected image multiplied by / cos θ, the effect of the distortion is canceled here. Then, a desired optical image is emitted to a predetermined position of the target by forming an image by Fourier transforming the readout light in which the influence of the distortion has been canceled.

In the image projection method according to the present invention, the hologram pattern writing step includes an object shape recognition step for acquiring three-dimensional information of the target.
A hologram pattern may be created to match the shape of the target based on the three-dimensional information of the target acquired in the object shape recognition step. With this configuration, it is possible to generate a hologram pattern for forming a three-dimensional pattern so as to match the shape of the target based on the three-dimensional information of the target acquired in the object shape recognition step.
The possibility that the target is irradiated with the distorted pattern is reduced, and more accurate image projection can be performed.

In the image projection method according to the present invention, the hologram pattern writing step includes an object position recognizing step for obtaining target position information, and based on the target position information obtained in the object position recognizing step. And generating a hologram pattern so as to match the position of the target. In this way, even if the position of the target to be projected is shifted from the desired position, a hologram pattern matching the target position is generated based on the target position information acquired in the object position recognition step. Since it is possible, it is possible to perform accurate image projection without depending on a change in the position of the target.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the same components are denoted by the same reference numerals, and redundant description will be omitted.

(First Embodiment) FIG. 1 is a plan view schematically showing a configuration of a laser marking device 10 as an image projection device according to a first embodiment of the present invention.

As shown, the laser marking device 10
Comprises a reflective spatial light modulator (SLM) 20, hologram pattern writing means 40, light projecting means 50, and Fourier lens 60.

The SLM 20 is a spatial light modulator of a phase modulation type using a parallel alignment nematic liquid crystal as a light modulation material. As shown in FIG. 2, the SLM 20 has an AR coating 21 on the incident surface of the writing light for preventing unnecessary reflection of the writing light.
Is provided with a glass substrate 22 which has been subjected to. A photoconductive layer 24 made of amorphous silicon (a-Si) whose resistance changes according to the intensity of the incident light via the ITO 23 is provided on a surface opposite to the incident surface of the glass substrate 22, and a dielectric multilayer. A mirror layer 25 made of a film is laminated. Also S
The LM 20 also has an AR coating 2 on the incident surface of the readout light.
6 is further provided. And
On the surface of the glass substrate 27 opposite to the incident surface, ITO2
8 are stacked, and the mirror layer 25 and the ITO 2
The alignment layers 29 and 30 are provided on the substrate 8, respectively.
These alignment layers 29 and 30 are connected to each other via a frame-shaped spacer 31 so as to face each other, and a nematic liquid crystal is filled in the frame of the spacer 31 to provide a liquid crystal layer.
2 are formed. The nematic liquid crystal in the light modulation layer 32 is aligned parallel or perpendicular to the surfaces of the alignment layers 29 and 30 by the alignment layers 29 and 30. A drive device 33 for applying a predetermined voltage is connected between the two ITOs 23 and 28.

As shown in FIG. 1, a hologram pattern writing means 40 is arranged on the side of the SLM 20 having the above-described structure on which writing light is incident.

The hologram pattern writing means 40
A light source 41 for emitting writing light, a transmission type liquid crystal television 42 for displaying an image of the writing light, a writing electric signal generator 43 for controlling image display on the transmission type liquid crystal television 42, An imaging lens 44 for imaging an image signal included in the writing light on the photoconductive layer 24 of the SLM 20 is provided.

On the other hand, on the side of the SLM 20 on which the readout light is incident, a light projecting means 50 is arranged on an optical axis inclined by an angle θ with respect to the normal in the normal to the incident surface. Note that the normal surface refers to a surface that includes any of the incident optical axis, the reflected optical axis, and the normal line of the mirror when the linearly polarized light enters the mirror and is reflected.

The light projecting means 50 includes a laser light source 51 for emitting readout light, a lens 52 for expanding readout light emitted from the laser light source 51, and adjusting the expanded readout light to parallel light. And a collimating lens 53.

A Fourier lens 60 for Fourier transforming the read light phase-modulated by the hologram pattern is arranged on the reflected light path of the read light.

Thus, the laser marking device 10 according to the present embodiment is configured.

Here, in the laser marking device 10 according to the present embodiment, the hologram pattern writing means 4
0, in particular, the structure of the electric signal generator 43 for writing.

That is, in the laser marking device 10 according to the present embodiment, since the reading light is obliquely incident on the spatial light modulator 20 at the incident angle θ, the incident angle is not included in the optical image irradiated on the sample T. Distortion occurs according to θ. That is, assuming that the hologram pattern width displayed on the liquid crystal television 42 is A, the readout light including the image information of the hologram pattern on the reflection optical path is distorted in the width direction and has a width of Ac.
osθ. As described above, since the readout light on the reflection optical path is distorted and multiplied by cos θ in the width direction, an optical image obtained by Fourier transforming the light is expanded in the width direction according to the incident angle θ.

In order to mark an accurate optical image on the sample T without being affected by the distortion, the electrical signal generator 43 for writing writes the optical image to be actually marked on the sample T in the width direction. A hologram pattern for the corrected image is obtained by multiplying the corrected image by 1 / cos θ, and displayed on the liquid crystal television 42. That is, the width of the optical image to be actually marked on the sample T is B
Then, the electrical signal generator 43 for writing has a width of B / c
A corrected image of osθ is created, and a hologram pattern for the corrected image is obtained and displayed on the liquid crystal television 42.

An example of the configuration of the electric signal generator 43 for writing such a hologram pattern is shown in FIG.
Is shown in the circuit block diagram of FIG.

As shown in the figure, when information of an optical image to be actually marked on the sample T is input to the electric signal generator 43 for writing, the optical image is created by the first computing unit 43a. Next, a corrected image obtained by multiplying the optical image by 1 / cos θ in the width direction is created by the multiplier 43b.
Then, the hologram pattern corresponding to the corrected image is obtained by the second computing unit 43c, and the result is displayed on the liquid crystal television 4.
2 is output.

As described above, the write electric signal generator 4
The liquid crystal television 3 may retrieve the hologram pattern for the desired optical image by calculation each time, but may call the hologram pattern data for the corrected image created in advance in consideration of the distortion and stored in storage means such as a memory. 42 may be displayed. In this way, the writing electrical signal generator 43 can display the hologram pattern on the liquid crystal television 42 only by reading the data of the hologram pattern stored in the storage means. That is, since it is not necessary to create a corrected image from a desired optical image and further create a hologram pattern, it is possible to rewrite the hologram pattern in the reflective spatial light modulator 20 at a video rate.

Next, the above laser marking device 10
A laser marking method as an image projection method according to an embodiment of the present invention using the method will be described.

First, the writing electric signal generator 43 sets a corrected image to a width obtained by multiplying the width of an optical image to be actually marked on the sample T by 1 / cos θ, and transmits a hologram pattern corresponding to the corrected image to the liquid crystal television 42. indicate.

Next, the writing light is emitted from the light source 41 on the writing light side toward the liquid crystal television 42. Then, the image information of the hologram pattern is written into the writing light when passing through the liquid crystal television 42. The writing light including the image information of the hologram pattern is imaged on the photoconductive layer 24 of the SLM 20 by the imaging lens 44. SLM2
Although an AC voltage of several volts is applied between the two ITOs 23 and 28 by the driving device 33, the electrical impedance of the photoconductive layer 24 varies depending on the pixel position depending on the image written on the photoconductive layer 24. I do. As a result, in the light modulation layer 32, the partial pressure of the applied voltage differs depending on the pixel position (hologram pattern writing step).

On the other hand, readout light of linear polarization is emitted from the laser light source 51. Then, the reading light is transmitted through the lens 52,
The light is adjusted to a parallel light by the collimating lens 53. At this time, a predetermined incident angle θ is applied to the light modulation layer 32 of the SLM 20.
Is incident as P-polarized light (reading light incidence step).

As described above, since the voltage applied to the light modulating layer 32 varies depending on the pixel position, the inclination of the liquid crystal molecules changes according to the voltage. At this time, the orientation direction of the liquid crystal molecules changes within the normal plane. As a result, the refractive index of the light modulation layer 32 changes depending on the pixel position. The read light incident on the light modulation layer 32 is phase-modulated by the change in the refractive index, reflected by the mirror layer 25, and output again from the incident surface.

At this time, the image information included in the readout light is distorted in the width direction and multiplied by cos θ, and the hologram pattern itself, which is the source of the image information included in the readout light, converts the desired optical image into the widthwise direction. Since the hologram pattern is a hologram pattern for the corrected image multiplied by 1 / cos θ, the effect of the distortion is consequently canceled. Then, the readout light including the image information in which the influence of the distortion has been canceled is subjected to Fourier transform by the Fourier lens 60 to form an image.
A desired optical image is marked at a predetermined position (Fourier transform step).

As described above, in the laser marking device 10 according to the present embodiment, when marking a desired optical image on the sample T, the hologram pattern writing means 40 multiplies the desired optical image by 1 / cos θ in the width direction. The hologram pattern corresponding to the corrected image is written in the reflective spatial light modulator 20. Therefore,
Even if the readout light including the image information of the hologram pattern reflected by the reflection type spatial light modulator 20 is distorted and multiplied by cos θ in the width direction, the hologram pattern itself converts the desired optical image into 1 / cos θ in the width direction. Since this corresponds to the multiplied corrected image, the effect of distortion is eventually canceled.
As a result, the read light including the image information of the hologram pattern is Fourier-transformed by the Fourier lens 60 to form an image, so that a desired optical image can be accurately marked at a predetermined position of the sample T.

Further, in the laser marking method according to the present embodiment, readout light is made incident on the reflective spatial light modulator 20 at a predetermined incident angle θ and phase-modulated by the hologram pattern to include image information of the hologram pattern. When the light is reflected toward the sample T in this state, the read light including the image information of the hologram pattern is distorted and multiplied by cos θ in a predetermined direction, but is written to the reflective spatial light modulator 20 in a hologram pattern writing step. Since the hologram pattern itself is a hologram pattern corresponding to a corrected image multiplied by 1 / cos θ in a predetermined direction with respect to a desired optical image, the effect of distortion is canceled here. As a result, the reading light from which the influence of the distortion has been canceled out is subjected to Fourier transform to form an image.
It is possible to accurately mark a desired optical image at a predetermined position.

(Second Embodiment) Next, a laser marking device according to a second embodiment of the present invention will be described with reference to FIG.

In the first embodiment described above, a case has been described in which a desired pattern is marked on the surface of the sample T set at a desired position. However, the setting position of the sample T is not always fixed. Not exclusively. If the position of the sample T is shifted from the desired position, and the sample T is irradiated with a pattern on the premise that the sample T is installed at the desired position, the pattern is enlarged and enlarged on the processed surface of the sample T.
It may be reduced or deformed, resulting in a decrease in marking accuracy.

Laser marking device 1 according to this embodiment
0 further includes an object position recognizing means for acquiring the position information of the sample T as shown in FIG. The object position recognizing means includes a light emitting element 72 such as a semiconductor laser and a light receiving element 74 such as a photodiode inside.
And a laser distance measuring device 70 having the following. The laser range finder 70 emits laser light from the light emitting element 72 toward the target T, receives the reflected light with the light receiving element 74, and measures the position (distance) of the target. The laser distance measuring device 70 is connected to the electric signal generator 43 for writing.

In the laser marking device 10, the position information of the target T measured by the laser distance measuring device 70 is sent to the writing electric signal generator 43 (object position recognition step). Then, an optical image to be actually irradiated and processed on the sample T is written into the electrical signal generator 4 for writing.
3, the electric signal generator 43 for writing
A hologram pattern corresponding to the desired optical image is obtained based on the position of the sample T, and the hologram pattern is displayed on the liquid crystal television 42.

Next, when the writing light is emitted from the light source 41 on the writing light side toward the liquid crystal television 42, the image information of the hologram pattern is written into the writing light when passing through the liquid crystal television 42. The writing light having this image information is imaged on the photoconductive layer 24 of the SLM 20 by the imaging lens 44 (hologram pattern writing step).

On the other hand, readout light of linearly polarized light is emitted from the laser light source 51. Then, the reading light is transmitted through the lens 52,
The light is adjusted to a parallel light by the collimating lens 53. At this time, a predetermined incident angle θ is applied to the light modulation layer 32 of the SLM 20.
Is incident as P-polarized light (reading light incidence step). The read light that has entered the light modulation layer 32 is phase-modulated by the hologram pattern, reflected by the mirror layer 25, and output again from the incident surface.

Then, the phase-modulated readout light is subjected to Fourier transformation by the Fourier lens 60 to form an image (Fourier transformation step).
The desired optical image corresponding to the position is illuminated.

As described above, since the laser marking device 10 according to the present embodiment is provided with the object position recognizing means for acquiring the position information of the sample T, a pattern matching the position of the sample T can be generated. This makes it possible to perform accurate marking without depending on a change in the position of the sample T.

(Third Embodiment) Next, a laser marking device according to a third embodiment of the present invention will be described with reference to FIG.

In the above-described first and second embodiments, the case where a desired pattern is marked on the processed surface of the sample T which is a plane has been described. However, the processed surface of the sample T is not always flat. Absent. If the processing surface of the sample T having a three-dimensional shape is irradiated with a pattern assuming a flat surface, the pattern is distorted in accordance with the unevenness of the processing surface of the sample T, which may cause a reduction in marking accuracy. There is.

Laser marking device 1 according to this embodiment
0 further includes an object shape recognition unit for acquiring three-dimensional information of the sample T as shown in FIG. The object shape recognizing means includes two image pickup devices 80 and 82 each capable of picking up an image of the sample T. These imaging devices 80 and 82 include a Fourier lens 60
Are arranged in a substantially symmetrical positional relationship with respect to the optical axis from the sample to the sample T.
It is connected to the.

In the laser marking device 10, the stereo images of the sample T imaged by the imaging devices 80 and 82 are sent to the writing electric signal generator 43, respectively. Then, a correspondence between pixels is obtained between images captured by the pair of imaging devices 80 and 82, a pixel shift amount of a corresponding point, that is, parallax is calculated, and a distance to the target is calculated using triangulation. In this way, three-dimensional information such as the unevenness of the sample T is calculated, and the three-dimensional shape of the sample T is recognized (object shape recognition step). In the laser marking device 10 according to the present embodiment, since the imaging devices 80 and 82 as the object shape recognizing unit can also acquire the position information of the target T, the imaging devices 80 and 82 can be used as the object position recognizing unit. Is also working.

When an optical image to be actually illuminated and processed on the sample T is input to the electric signal generator 43 for writing, a hologram pattern corresponding to the desired optical image is formed based on the three-dimensional shape of the sample T. The obtained hologram pattern is displayed on the liquid crystal television 42.

Next, when writing light is emitted from the light source 41 on the writing light side toward the liquid crystal television 42, image information of a hologram pattern is written into the writing light when passing through the liquid crystal television 42. The writing light having this image information is imaged on the photoconductive layer 24 of the SLM 20 by the imaging lens 44 (hologram pattern writing step).

On the other hand, a linearly polarized readout light is emitted from the laser light source 51. Then, the reading light is transmitted through the lens 52,
The light is adjusted to a parallel light by the collimating lens 53. At this time, a predetermined incident angle θ is applied to the light modulation layer 32 of the SLM 20.
Is incident as P-polarized light (reading light incidence step). The read light that has entered the light modulation layer 32 is phase-modulated by the hologram pattern, reflected by the mirror layer 25, and output again from the incident surface.

Then, the phase-modulated readout light is Fourier transformed by the Fourier lens 60 to form an image (Fourier transform step), whereby a desired optical image conforming to the shape of the sample T is formed on the three-dimensional surface of the sample T. Irradiated.

As described above, since the laser marking device 10 according to the present embodiment is provided with the object shape recognizing means for acquiring the three-dimensional information of the sample T, it is possible to generate a pattern matching the shape of the sample T. This makes it possible to suppress the distortion of the irradiated pattern on the surface of the sample T, thereby suppressing a decrease in marking accuracy.

The present invention is not limited to the above embodiment, and various modifications are possible.

For example, in the above-described embodiment, a case was considered in which the readout light is made incident at a predetermined incident angle θ in the normal plane. Therefore, the hologram pattern written in the reflection type spatial light modulator 20 has a desired optical image. 1 / in the width direction
This corresponds to a corrected image multiplied by cos θ and equalized in the height direction. On the other hand, when the readout light is made to enter the incident surface from an arbitrary direction, the readout light incident direction is divided into two directions of the width direction and the height method, and the incident angle in the width direction is α, the height is The incident angle in the direction is β. And
The writing electric signal generator 43 has a structure capable of writing a hologram pattern for a corrected image obtained by multiplying a desired optical image by 1 / cos α in the width direction and by 1 / cos β in the height direction to the reflective spatial light modulator 20. And In this way, even when the readout light is incident on the incident surface of the reflective spatial light modulator 20 from any direction, the sample T
It is possible to accurately mark a desired optical image at a predetermined position.

In the above-described embodiment, the laser marking device 10 has been described as an image projection device. However, the present invention is not limited to this, and can be widely applied to an image projection device such as an exposure device.

[0063]

According to the image projection apparatus of the present invention, when the hologram pattern writing means irradiates a target with a desired optical image, the hologram pattern writing means shifts the desired optical image by one in a predetermined direction.
It has a structure in which a hologram pattern corresponding to the corrected image multiplied by / cos θ can be written in the reflective spatial light modulator. Therefore, even if the readout light including the image information of the hologram pattern reflected by the reflection type spatial light modulator is distorted and multiplied by cos θ in a predetermined direction, the hologram pattern itself shifts a desired optical image by 1 / in a predetermined direction. Since this corresponds to the corrected image multiplied by cos θ, the effect of distortion is eventually canceled. As a result, it is possible to accurately irradiate a desired optical image to a predetermined position of the target by performing Fourier transform on the readout light including the image information of the hologram pattern by the Fourier lens and forming an image.

According to the image projection method of the present invention, the readout light is made incident on the reflection type spatial light modulator at a predetermined incident angle θ, phase-modulated by the hologram pattern, and projected onto the target in a state containing the image information of the hologram pattern. When reflected toward the hologram pattern, the readout light including the image information of the hologram pattern is distorted and cosed in a predetermined direction.
The hologram pattern itself written in the reflective spatial light modulator in the hologram pattern writing step is 1 / cos θ in a predetermined direction with respect to a desired optical image.
Since the hologram pattern corresponds to the multiplied corrected image, the influence of the distortion is canceled here. As a result, it is possible to accurately irradiate a desired optical image to a predetermined position of the target by forming an image by performing Fourier transform on the read light in which the influence of the distortion has been canceled.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a configuration of a laser marking device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a spatial light modulator.

FIG. 3 is a circuit block diagram illustrating an example of a configuration of a writing electric signal generator.

FIG. 4 is a plan view schematically showing a configuration of a laser marking device according to a second embodiment of the present invention.

FIG. 5 is a plan view schematically showing a configuration of a laser marking device according to a third embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating a state in which read light including image information of a hologram pattern is reflected by a spatial light modulator and is distorted.

7A and 7B show a state in which an optical image irradiated by a conventional technique is distorted. FIG. 7A is a desired optical image to be irradiated on a target, and FIG. 7B is distorted in a width direction. 4 shows an actual optical image.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Laser marking apparatus, 20 ... Reflection type spatial light modulator, 40 ... Hologram pattern writing means, 50 ... Emission means, 60 ... Fourier lens, 70 ... Laser distance measuring apparatus, 80, 82 ... Imaging apparatus, T ... Sample .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 31/12 G02F 1/1335 530 (72) Inventor Tsutomu Hara 1 1126 Nomachi, Ichinomachi, Hamamatsu City, Shizuoka Prefecture Hamamatsu Within Photonics Co., Ltd. (72) Inventor Teruo Hiruma 1126 No. 1, Nomachi, Hamamatsu City, Shizuoka Prefecture F-term within Hamamatsu Photonics Co., Ltd. KA18 LA02 LA03 LA12 NA25 4E068 CD05 DA00 5F089 BA02 BB01

Claims (7)

[Claims] 1. A reflection type spatial light modulator, hologram pattern writing means for writing a hologram pattern in the reflection type spatial light modulator, and a readout light with a predetermined incident angle θ to the reflection type spatial light modulator. And a Fourier lens for performing Fourier transform of the readout light phase-modulated in the reflection-type spatial light modulator. The hologram pattern writing means includes a target optical image An image projection device, wherein a hologram pattern corresponding to a corrected image obtained by multiplying the desired optical image by 1 / cos θ in a predetermined direction can be written to the reflection-type spatial light modulator when irradiating light. . 2. The hologram pattern writing unit according to claim 1, further comprising a storage unit configured to store hologram pattern data corresponding to the corrected image previously obtained for the desired optical image. An image projection device according to claim 1. 3. An object shape recognizing unit for acquiring three-dimensional information of the target, wherein the hologram pattern writing unit is configured to execute the target based on the three-dimensional information of the target acquired by the object shape recognizing unit. 3. The image projection device according to claim 1, wherein the image projection device has a structure capable of generating a hologram pattern matching the shape of the image projection device. 4. The apparatus according to claim 1, further comprising an object position recognizing unit for obtaining the position information of the target, wherein the hologram pattern writing unit is configured to detect the position of the target based on the position information of the target obtained by the object position recognizing unit. The image projection device according to any one of claims 1 to 3, wherein the image projection device has a structure capable of generating a hologram pattern that conforms to (1). 5. A reflection type spatial light modulator having a predetermined incident angle θ
A step of irradiating a target with a desired optical image, and forming a hologram pattern corresponding to a corrected image obtained by multiplying the desired optical image by 1 / cos θ in a predetermined direction, and performing the reflection. A hologram pattern writing step of writing to a spatial light modulator, and a Fourier transform step of performing a Fourier transform on the read light phase-modulated by the hologram pattern written to the reflection type spatial light modulator to obtain a desired optical image. And an image projection method. 6. The hologram pattern writing step includes an object shape recognition step for acquiring three-dimensional information of the target, and the target hologram pattern is written based on the three-dimensional information of the target acquired in the object shape recognition step. The image projection method according to claim 5, wherein the hologram pattern is created so as to conform to a shape. 7. The hologram pattern writing step includes an object position recognition step for acquiring position information of the target, and the position of the target is determined based on the position information of the target acquired in the object position recognition step. The hologram pattern is generated so as to match.
2. The image projection method according to 1.,