JP3980822B2 - Image projection apparatus and image projection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image projecting apparatus and an image projecting method using Fourier transform that performs Fourier transform on light phase-modulated by a spatial light modulator and irradiates a target with an optical image obtained.
[0002]
[Prior art]
There are two types of spatial light modulators widely used in image projection devices, such as intensity modulation type and phase modulation type, and the latter phase modulation type is particularly promising in fields such as optical information processing and hologram processing. 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, and a reflection type is preferably used in order to increase the light use efficiency.
[0004]
However, in a reflective spatial light modulator, the incident surface of the readout light and the exit surface of the modulated light are on the same plane, and normally the modulated light is separated from the readout light using a half mirror. The efficiency of use decreases and the merit of the phase modulation type is lost.
[0005]
Therefore, the reading light is obliquely incident on the incident surface, and the modulated light is extracted by shifting the optical axes of the reading light and the modulating light, thereby eliminating the use of the half mirror and suppressing the decrease in the light utilization efficiency. Has been developed.
[0006]
[Problems to be solved by the invention]
However, in the image projection apparatus that simply uses the above-described conventional technique in which the readout light is incident obliquely on the incident surface of the spatial light modulator, the size of the optical image irradiated on the target is compared with the design size. There is a problem that the space to be projected protrudes. In particular, in a laser marking apparatus or the like, it is necessary to accurately irradiate and mark a predetermined place with an optical image of a predetermined size. Therefore, in such a field, the protrusion of the optical image has been a serious problem.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide an image projection apparatus and an image projection method that can irradiate an optical image with high accuracy onto a target.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the inventors diligently studied the problem of the protrusion of the optical image that occurs when the readout light is obliquely incident on the spatial light modulator. And it discovered that the distortion according to the incident angle (theta) of reading light arises in the optical image irradiated to a target.
[0009]
That is, as shown in FIG. 6, when the readout light is incident on the spatial light modulator at a predetermined incident angle θ and is phase-modulated and reflected by the hologram pattern, the modulated light is multiplied by cos θ in the width direction. Therefore, the optical image obtained by Fourier transforming the modulated light multiplied by cos θ is compared with the desired optical image shown in FIG. 7A according to the incident angle θ as shown in FIG. It was found that the image was extended in the width direction.
[0010]
The present invention has been made based on the above findings. That is, the image projection apparatus of the present invention includes a reflective spatial light modulator, hologram pattern writing means for writing a hologram pattern in the reflective spatial light modulator, and a predetermined incident angle θ on the reflective spatial light modulator. A holographic pattern, comprising: a light projecting means for entering the readout light; and a Fourier lens for subjecting the readout light phase-modulated by the reflective spatial light modulator and reflected at the angle θ to Fourier transform to form an image on the target. The writing means creates a corrected image obtained by multiplying the desired optical image by a factor of 1 / cos θ in a predetermined direction so as to cancel the influence of distortion generated when the reading light is incident obliquely when the target is irradiated with the desired optical image. Write the corresponding hologram pattern into the reflective spatial light modulator Write electrical signal generator It is characterized by having.
[0011]
In this image projection apparatus, the readout light incident on the reflective spatial light modulator with a predetermined incident angle θ is phase-modulated by the hologram pattern and reflected toward the target in a state including the image information of the hologram pattern. The readout light including the image information of the hologram pattern receives distortion and is multiplied by cos θ in a predetermined direction. However, the hologram pattern itself that is the source of the image information included in the readout light is 1 in the predetermined direction with respect to the desired optical image. Since the hologram pattern corresponds to the corrected image multiplied by / cos θ, the influence of the distortion is canceled here. Then, the readout light in which the influence of the distortion is canceled is subjected to Fourier transformation with a Fourier lens to form an image, whereby a desired optical image is irradiated to a predetermined position of the target.
[0012]
In the image projection apparatus of the present invention, the hologram pattern writing means may include storage means for storing hologram pattern data corresponding to a corrected image obtained in advance for a desired optical image. . In this way, the hologram pattern writing unit can write the hologram pattern into the reflective spatial light modulator only by reading the hologram pattern data stored in the storage unit. That is, since it is possible to save 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 a video rate in the reflective spatial light modulator.
[0013]
The image projection apparatus according to the present invention further includes an object shape recognition unit for acquiring three-dimensional information of the target, and includes a hologram pattern writing unit. Electric signal generator for writing Is a hologram pattern that matches the shape of the target based on the three-dimensional information of the target acquired by the object shape recognition means. Generate This may be a feature. In this way, the hologram pattern writing means can generate a hologram pattern that forms a pattern three-dimensionally to match the shape of the target based on the three-dimensional information of the target acquired by the object shape recognition means. Therefore, there is less possibility that a distorted pattern is irradiated to the target, and it becomes possible to project a more accurate image.
[0014]
The image projection apparatus according to the present invention further includes an object position recognizing unit for acquiring target position information, and includes a hologram pattern writing unit. Electric signal generator for writing Is a hologram pattern that matches the position of the target based on the position information of the target acquired by the object position recognition means. Generate This may be a feature. In this way, even if the position of the target to be image projected is deviated from the desired position, the hologram pattern writing means can set the target position based on the position information of the target acquired by the object position recognition means. Since the matched hologram pattern can be generated, accurate image projection can be performed without depending on the variation in the position of the target.
[0015]
Further, the image projection method of the present invention includes a reading light incident step for inputting the reading light to the reflective spatial light modulator at a predetermined incident angle θ, and irradiating the target with a desired optical image. To cancel the influence of distortion that occurs when the readout light is incident obliquely, A hologram pattern writing step for creating a hologram pattern corresponding to a corrected image obtained by multiplying the desired optical image in a predetermined direction by 1 / cos θ and writing the hologram pattern in the reflective spatial light modulator, and the hologram written in the reflective spatial light modulator Phase modulated by pattern Reflected at an angle θ Fourier transform the read light Focus on the target And a Fourier transform step for obtaining a desired optical image.
[0016]
In this image projection method, the readout light incident on the reflective spatial light modulator with a predetermined incident angle θ is phase-modulated by the hologram pattern and reflected toward the target in a state including the image information of the hologram pattern. The readout light including the image information of the hologram pattern receives distortion and is multiplied by cos θ in a predetermined direction. However, the hologram pattern itself that is the source of the image information included in the readout light is 1 in the predetermined direction with respect to the desired optical image. Since the hologram pattern corresponds to the corrected image multiplied by / cos θ, the influence of the distortion is canceled here. Then, a desired optical image is irradiated onto a predetermined position of the target by forming an image by performing Fourier transform on the readout light in which the influence of the distortion is canceled.
[0017]
In the image projection method according to the present invention, the hologram pattern writing step includes an object shape recognition step for acquiring target three-dimensional information, and based on the target three-dimensional information acquired in the object shape recognition step. A hologram pattern may be created so as to match the shape of the target. In this way, it is possible to generate a hologram pattern that forms a three-dimensional pattern so as to match the target shape based on the target three-dimensional information acquired in the object shape recognition step. Therefore, it is possible to project a more accurate image.
[0018]
In the image projection method according to the present invention, the hologram pattern writing step includes an object position recognition step for acquiring position information of the target, and the target based on the position information of the target acquired in the object position recognition step. The hologram pattern may be generated so as to match the position of. In this way, even when the target position of the image projection target is shifted from the desired position, a hologram pattern that matches the target position is generated based on the target position information acquired in the object position recognition step. Therefore, accurate image projection can be performed without depending on the variation of the target position.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.
[0020]
(First embodiment)
FIG. 1 is a plan view schematically showing a configuration of a laser marking apparatus 10 as an image projection apparatus according to the first embodiment of the present invention.
[0021]
As shown in the figure, the laser marking device 10 includes a reflective spatial light modulator (SLM) 20, a hologram pattern writing unit 40, a light projecting unit 50, and a Fourier lens 60.
[0022]
The SLM 20 is a phase modulation type spatial light modulator using a parallel alignment nematic liquid crystal as a light modulation material. As shown in FIG. 2, the SLM 20 includes a glass substrate 22 having an AR coating 21 for preventing unnecessary reflection of writing light on the writing light incident surface. On the surface opposite to the incident surface of the glass substrate 22, a photoconductive layer 24 made of amorphous silicon (a-Si) whose resistance changes according to the intensity of incident light through the ITO 23, and a dielectric multilayer A mirror layer 25 made of a film is laminated. The SLM 20 further includes a glass substrate 27 having an AR coating 26 on the reading light incident surface. An ITO 28 is laminated on the surface of the glass substrate 27 opposite to the incident surface, and alignment layers 29 and 30 are provided on the mirror layer 25 and the ITO 28, respectively. Then, these alignment layers 29 and 30 are opposed to each other and connected via a frame-shaped spacer 31, a nematic liquid crystal is filled in the frame of the spacer 31, a liquid crystal layer is provided, and a light modulation layer 32 is formed. Yes. Due to the alignment layers 29 and 30, 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. A driving device 33 for applying a predetermined voltage is connected between the ITOs 23 and 28.
[0023]
As shown in FIG. 1, hologram pattern writing means 40 is arranged on the side on which the writing light of the SLM 20 having the above-described configuration is incident.
[0024]
The hologram pattern writing means 40 includes a light source 41 for emitting write light, a transmissive liquid crystal television 42 for displaying an image of the write light, and a writing light for controlling image display on the transmissive liquid crystal television 42. An electrical signal generator 43 and an imaging lens 44 for imaging an image signal included in the writing light on the photoconductive layer 24 of the SLM 20 are provided.
[0025]
On the other hand, on the side of the SLM 20 where the readout light is incident, the light projecting means 50 is disposed on the optical axis inclined at an angle θ with respect to the normal line within the normal plane of the incident surface. Note that the normal plane refers to a plane including any of the incident optical axis, the reflected optical axis, and the mirror normal when linearly polarized light is incident on the mirror and reflected.
[0026]
The light projecting means 50 includes a laser light source 51 for emitting readout light, a lens 52 for enlarging the readout light emitted from the laser light source 51, and a collimator for adjusting the enlarged readout light to parallel light. And a lens 53.
[0027]
A Fourier lens 60 for Fourier transforming the readout light phase-modulated by the hologram pattern is disposed on the reflected light path of the readout light.
[0028]
Thus, the laser marking device 10 according to the present embodiment is configured.
[0029]
Here, the laser marking device 10 according to the present embodiment is characterized by the structure of the hologram pattern writing means 40, particularly the writing electric signal generator 43.
[0030]
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 optical image irradiated on the sample T corresponds to the incident angle θ. Distortion occurs. That is, if 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 reflected light path is distorted in the width direction and the width becomes A cos θ. Thus, since the readout light on the reflected light path is distorted and multiplied by cos θ in the width direction, the optical image obtained by Fourier transforming this is extended in the width direction according to the incident angle θ.
[0031]
In order to mark an accurate optical image on the sample T without being affected by this distortion, the writing electrical signal generator 43 converts the optical image to be actually marked on the sample T in the width direction 1 /. An image multiplied by cos θ is used as a corrected image, and a hologram pattern for the corrected image is obtained and displayed on the liquid crystal television 42. In other words, if the width of the optical image to be actually marked on the sample T is B, the writing electric signal generator 43 creates a corrected image having a width of B / cos θ, and obtains a hologram pattern for the corrected image. Displayed on the liquid crystal television 42.
[0032]
An example of the configuration of the writing electric signal generator 43 for creating such a hologram pattern is shown in the circuit block diagram of FIG.
[0033]
As shown in the figure, when information of an optical image to be actually marked on the sample T is input to the writing electric signal generator 43, the optical image is created by the first calculator 43a. Next, the multiplier 43b creates a corrected image obtained by multiplying the optical image by 1 / cos θ in the width direction. Then, the second computing unit 43 c obtains a hologram pattern corresponding to the corrected image, and the result is output toward the liquid crystal television 42.
[0034]
As described above, the writing electric signal generator 43 may obtain a hologram pattern for a desired optical image by calculation each time, but a modified image that is created in advance in consideration of distortion and stored in a storage means such as a memory. It is also possible to call up and display the hologram pattern data on the liquid crystal television 42. In this way, the writing electrical signal generator 43 can display the hologram pattern on the liquid crystal television 42 only by reading the hologram pattern data stored in the storage means. That is, since it is possible to save the trouble of creating a corrected image from a desired optical image and further creating a hologram pattern, the hologram pattern can be rewritten to the reflective spatial light modulator 20 at a video rate.
[0035]
Next, a laser marking method as an image projection method according to an embodiment of the present invention using the above-described laser marking device 10 will be described.
[0036]
First, the writing electric signal generator 43 sets a corrected image by multiplying the width of the optical image to be actually marked on the sample T by 1 / cos θ, and displays a hologram pattern for the corrected image on the liquid crystal television 42.
[0037]
Next, writing light is emitted from the light source 41 on the writing light side toward the liquid crystal television 42. Then, image information of the hologram pattern is written in 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. An AC voltage of several volts is applied between the ITOs 23 and 28 of the SLM 20 by the drive 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. To do. As a result, the divided voltage applied to the light modulation layer 32 varies depending on the pixel position (hologram pattern writing step).
[0038]
On the other hand, linearly polarized readout light is emitted from the laser light source 51. Then, the readout light is adjusted to parallel light by the lens 52 and the collimating lens 53. At this time, the light modulation layer 32 of the SLM 20 is incident as P-polarized light with a predetermined incident angle θ (reading light incident step).
[0039]
As described above, since the divided voltage applied to the light modulation layer 32 differs depending on the pixel position, the inclination of the liquid crystal molecules changes according to this voltage. At this time, the orientation direction of the liquid crystal molecules changes within the slope. As a result, the refractive index of the light modulation layer 32 changes depending on the pixel position. The readout light incident on the light modulation layer 32 is phase-modulated by this refractive index change, reflected by the mirror layer 25, and output again from the incident surface.
[0040]
At this time, the image information included in the readout light is distorted in the width direction and multiplied by cos θ. However, the hologram pattern itself that is the source of the image information included in the readout light has a desired optical image in the width direction 1 /. Since this is a hologram pattern for the corrected image multiplied by cos θ, the influence of the distortion is canceled as a result. Then, a desired optical image is marked at a predetermined position of the sample T by performing Fourier transform on the readout light including the image information in which the influence of the distortion is canceled by the Fourier lens 60 to form an image (Fourier transform). Step).
[0041]
As described above, in the laser marking device 10 according to the present embodiment, the hologram pattern writing unit 40, when marking a desired optical image on the sample T, is a corrected image obtained by multiplying the desired optical image by 1 / cos θ in the width direction. Has a structure in which a hologram pattern corresponding to the above can be 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 reflective spatial light modulator 20 is distorted and multiplied by cos θ in the width direction, the hologram pattern itself can reduce the desired optical image by 1 in the width direction. Since this corresponds to the corrected image multiplied by / cos θ, the influence of the distortion is canceled as a result. As a result, it is possible to mark a desired optical image with high accuracy at a predetermined position of the sample T by forming an image by performing Fourier transform on the readout light including the image information of the hologram pattern by the Fourier lens 60.
[0042]
Further, in the laser marking method according to the present embodiment, the reading light is incident on the reflective spatial light modulator 20 at a predetermined incident angle θ, and the phase is modulated by the hologram pattern to include the image information of the hologram pattern. When reflected toward T, the readout light including the image information of this hologram pattern is distorted and multiplied by cos θ in a predetermined direction, but the hologram written in the reflective spatial light modulator 20 in the hologram pattern writing step Since the 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 influence of distortion is canceled here. As a result, a desired optical image can be accurately marked at a predetermined position on the sample T by performing Fourier transform on the readout light in which the influence of the distortion is canceled and forming an image.
[0043]
(Second Embodiment)
Next, a laser marking device according to a second embodiment of the present invention will be described with reference to FIG.
[0044]
In the above-described first embodiment, the case where a desired pattern is marked on the surface of the sample T installed at a desired position has been described, but the installation position of the sample T is not always fixed. If the installation position of the sample T is deviated from the desired position, and the sample T is irradiated with a pattern on the assumption that the sample T is installed at the desired position, the pattern is enlarged / reduced / There is a risk that the accuracy of marking will be reduced due to deformation.
[0045]
In view of such a problem, the laser marking device 10 according to the present embodiment further includes an object position recognition unit for acquiring position information of the sample T as shown in FIG. This object position recognizing means includes a laser distance measuring device 70 having a light emitting element 72 such as a semiconductor laser and a light receiving element 74 such as a photodiode. The laser distance measuring device 70 emits laser light from the light emitting element 72 toward the target T, receives the reflected light by the light receiving element 74, and measures the position (distance) of the target. The laser distance measuring device 70 is connected to the writing electric signal generator 43.
[0046]
In this 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). When an optical image to be actually irradiated and processed on the sample T is input to the writing electric signal generator 43, the writing electric signal generator 43 corresponds to the desired optical image based on the position of the sample T. A hologram pattern to be obtained is obtained, and the hologram pattern is displayed on the liquid crystal television 42.
[0047]
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 in 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).
[0048]
On the other hand, linearly polarized readout light is emitted from the laser light source 51. Then, the readout light is adjusted to parallel light by the lens 52 and the collimating lens 53. At this time, the light modulation layer 32 of the SLM 20 is incident as P-polarized light with a predetermined incident angle θ (reading light incident step). The readout light incident on 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.
[0049]
Then, the phase-modulated readout light is subjected to Fourier transform by the Fourier lens 60 to form an image (Fourier transform step), whereby the sample T is irradiated with a desired optical image that matches the position of the sample T.
[0050]
As described above, since the laser marking device 10 according to the present embodiment includes the object position recognition unit for acquiring the position information of the sample T, it is possible to generate a pattern that matches the position of the sample T. Accurate marking can be performed without depending on the variation of the position of the sample T.
[0051]
(Third embodiment)
Next, a laser marking apparatus according to a third embodiment of the present invention will be described with reference to FIG.
[0052]
In the first and second embodiments described above, the case where a desired pattern is marked on the processing surface of the sample T that forms a plane has been described. However, the processing surface of the sample T is not always flat. If the processing surface of the sample T having a three-dimensional shape is irradiated with a pattern assuming a flat surface, the pattern may be distorted in accordance with the unevenness of the processing surface of the sample T, and the marking accuracy may be reduced. There is.
[0053]
In view of such a problem, the laser marking device 10 according to the present embodiment further includes object shape recognition means for acquiring three-dimensional information of the sample T as shown in FIG. This object shape recognizing means includes two imaging devices 80 and 82 each capable of capturing an image of the sample T. These imaging devices 80 and 82 are arranged in a substantially symmetrical positional relationship with respect to the optical axis from the Fourier lens 60 to the sample T, and are connected to the writing electric signal generator 43, respectively.
[0054]
In the laser marking device 10, the stereo images of the sample T imaged by the imaging devices 80 and 82 are respectively sent to the writing electric signal generator 43. Then, a correspondence between pixels is obtained between the images captured by the pair of imaging devices 80 and 82, a pixel shift amount of the corresponding point, that is, a parallax is calculated, and a distance to the target is calculated using triangulation. In this way, the 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 recognition unit can also acquire the position information of the target T, the imaging devices 80 and 82 serve as the object position recognition unit. Is also functioning.
[0055]
Then, when an optical image to be actually irradiated and processed on the sample T is input to the writing electric signal generator 43, a hologram pattern corresponding to the desired optical image is obtained based on the three-dimensional shape of the sample T. The hologram pattern is displayed on the liquid crystal television 42.
[0056]
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 in 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).
[0057]
On the other hand, linearly polarized readout light is emitted from the laser light source 51. Then, the readout light is adjusted to parallel light by the lens 52 and the collimating lens 53. At this time, the light modulation layer 32 of the SLM 20 is incident as P-polarized light with a predetermined incident angle θ (reading light incident step). The readout light incident on 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.
[0058]
Then, the phase-modulated readout light is subjected to Fourier transformation by the Fourier lens 60 to form an image (Fourier transformation step), so that a desired optical image matching the shape of the sample T is irradiated onto the three-dimensional surface of the sample T. .
[0059]
As described above, since the laser marking device 10 according to the present embodiment includes the object shape recognition means for acquiring the three-dimensional information of the sample T, it is possible to generate a pattern that matches the shape of the sample T. It is possible to suppress a decrease in marking accuracy by suppressing distortion of the irradiated pattern on the surface of the sample T.
[0060]
In addition, this invention is not limited to above-described embodiment, A various deformation | transformation is possible.
[0061]
For example, in the above-described embodiment, since the case where the reading light is incident at a predetermined incident angle θ within the normal plane is considered, the hologram pattern written in the reflective spatial light modulator 20 has a desired optical image in the width direction. This corresponds to a corrected image that has been multiplied by 1 / cos θ and the same size in the height direction. On the other hand, when reading light is incident on the incident surface from an arbitrary direction, the incident direction of the reading light is decomposed into two directions of the width direction and the height method, and the incident angle in the width direction is α and the height. Let the incident angle in the direction be β. Then, the writing electric signal generator 43 can write a hologram pattern for the corrected image obtained by multiplying the desired optical image by 1 / cos α in the width direction and 1 / cos β in the height direction to the reflective spatial light modulator 20. The structure is In this way, even when the readout light is incident on the incident surface of the reflective spatial light modulator 20 from an arbitrary direction, a desired optical image is accurately marked at a predetermined position of the sample T. It becomes possible.
[0062]
In the above-described embodiment, the laser marking apparatus 10 has been described as the image projection apparatus. However, the present invention is not limited to this and can be widely applied to an image projection apparatus such as an exposure apparatus.
[0063]
【The invention's effect】
In the image projection apparatus of the present invention, the hologram pattern writing means applies the hologram pattern corresponding to the corrected image obtained by multiplying the desired optical image by a factor of 1 / cos θ when the target is irradiated with the desired optical image. The optical modulator has a writable structure. Therefore, even if the readout light including the image information of the hologram pattern reflected by the reflective spatial light modulator is distorted and multiplied by cos θ in the predetermined direction, the hologram pattern itself converts the desired optical image in the predetermined direction 1 / Since this corresponds to the corrected image multiplied by cos θ, the influence of the distortion is canceled as a result. As a result, it is possible to accurately irradiate a predetermined position of the target with a desired optical image by forming an image by performing Fourier transform on the readout light including the image information of the hologram pattern with a Fourier lens.
[0064]
In the image projection method of the present invention, the readout light is incident on the reflective spatial light modulator at a predetermined incident angle θ, phase-modulated by the hologram pattern, and reflected toward the target in a state including the image information of the hologram pattern. In this case, the readout light including the image information of the hologram pattern is distorted and multiplied by cos θ in a predetermined direction. However, the hologram pattern itself written in the reflective spatial light modulator in the hologram pattern writing step is the desired optical Since the hologram pattern corresponds to the corrected image multiplied by 1 / cos θ in the predetermined direction with respect to the image, the influence of the distortion is canceled here. As a result, it is possible to accurately irradiate a predetermined optical position to a predetermined position of the target by forming an image by performing Fourier transform on the readout light in which the influence of the distortion is canceled.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing a configuration of a laser marking apparatus according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a configuration of a spatial light modulator.
FIG. 3 is a circuit block diagram showing 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 showing a state in which readout 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 with a conventional technique is distorted. FIG. 7A shows a desired optical image to be irradiated on a target, and FIG. 7B shows a distortion in the width direction. An actual optical image is shown.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Laser marking apparatus, 20 ... Reflection type spatial light modulator, 40 ... Hologram pattern writing means, 50 ... Projection means, 60 ... Fourier lens, 70 ... Laser ranging apparatus, 80, 82 ... Imaging apparatus, T ... Sample .

Claims (7)

A reflection type spatial light modulator; hologram pattern writing means for writing a hologram pattern in the reflection type spatial light modulator; and a projection for inputting readout light to the reflection type spatial light modulator at a predetermined incident angle θ. An optical means, and a Fourier lens for subjecting the readout light phase-modulated by the reflective spatial light modulator and reflected at an angle θ to Fourier transform and form an image on a target,
The holographic pattern writing means irradiates the target optical image in a predetermined direction by 1 / cos θ times so as to cancel the influence of distortion generated when the read light is incident obliquely when the target optical image is irradiated onto the target. image projection apparatus characterized by a having it electrical signal generator for write No write write a hologram pattern to the reflective spatial light modulator corresponding to the modified image. The image projection according to claim 1, wherein the hologram pattern writing unit includes a storage unit that stores data of a hologram pattern corresponding to the corrected image obtained in advance for the desired optical image. apparatus. The apparatus further comprises object shape recognition means for obtaining the three-dimensional information of the target, and the writing electric signal generator of the hologram pattern writing means is based on the three-dimensional information of the target obtained by the object shape recognition means. The image projection apparatus according to claim 1, wherein a hologram pattern matching the shape of the target is generated . The apparatus further comprises object position recognition means for acquiring the position information of the target, and the writing electric signal generator of the hologram pattern writing means is based on the position information of the target acquired by the object position recognition means. The image projection apparatus according to claim 1, wherein a hologram pattern that matches the position of the target is generated . A readout light incident step for entering the readout light at a predetermined incident angle θ into the reflective spatial light modulator;
A hologram corresponding to a corrected image obtained by multiplying the desired optical image by 1 / cos θ in a predetermined direction so as to cancel the influence of distortion generated when the read light is obliquely incident upon irradiating the target with the desired optical image. Hologram pattern writing step of creating a pattern and writing to the reflective spatial light modulator;
A Fourier transform step of obtaining a desired optical image that forms an image on a target by Fourier transforming the readout light phase-modulated by the hologram pattern written in the reflective spatial light modulator and reflected at an angle θ ;
An image projection method comprising: The hologram pattern writing step includes an object shape recognition step for acquiring three-dimensional information of the target, and matches the shape of the target based on the three-dimensional information of the target acquired in the object shape recognition step. To create the hologram pattern,
The image projection method according to claim 5, wherein: The hologram pattern writing step includes an object position recognition step for acquiring position information of the target, and matches the position of the target based on the position information of the target acquired in the object position recognition step. Generate hologram pattern,
The image projection method according to claim 5, wherein the image projection method is an image projection method.

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