JP2025119866A - Light distribution generation device - Google Patents

Abstract

In a technology for generating a three-dimensional light distribution based on a phase distribution image, the light intensity of the three-dimensional light distribution can be modulated to a desired value regardless of the form of the three-dimensional light distribution to be generated.
[Solution] The device comprises a spatial light modulator 5 capable of modulating the phase distribution of light, a light source unit 1 that emits light to illuminate the spatial light modulator 5, a light intensity modulation unit 6 that can modulate the intensity of the light emitted from the light source unit 1, and a signal processing unit 7 that sends an instruction signal related to aspect information of the phase distribution image to the light intensity modulation unit 6 so that the intensity of the light emitted from the light source unit 1 can be modulated in the light intensity modulation unit 6 based on the aspect information of the phase distribution image in synchronization with the display timing of the phase distribution image on the spatial light modulator 5, and is configured so that a three-dimensional light distribution 8 having a desired intensity is dynamically generated at a position a predetermined distance from the spatial light modulator 5 based on the aspect of the phase distribution image displayed on the spatial light modulator.
[Selected Figure] Figure 1

Description

The present invention relates to a light distribution generating device, and in particular to a light distribution generating device that generates three-dimensional light distributions using holography technology, such as computer-generated holograms and phase holograms (similar in concept to kinoforms; hereinafter, phase holograms and kinoforms will be collectively referred to as phase holograms, etc.).

Technology for generating and controlling desired three-dimensional light distributions in time and space is required in a variety of fields, including laser processing, optical data storage, 3D displays, AR/VR displays, microscopy, and optical communications.

A commonly known technique for modulating the complex amplitude distribution of light is to display an amplitude (or intensity) hologram image generated by calculating interference and diffraction on an amplitude modulation spatial light modulator (see, for example, Non-Patent Document 1 below). This technique involves irradiating a spatial light modulator displaying amplitude hologram information with light, and then generating the desired three-dimensional light distribution on a plane a predetermined distance away from the spatial light modulator based on the reflected light carrying the amplitude hologram information from the spatial light modulator, with additional processing added to remove unnecessary diffracted light components as needed. However, because this technique uses an amplitude modulation spatial light modulator, the light utilization efficiency is extremely low, ranging from a few percent to less than a dozen percent, resulting in significant loss of light energy.

To solve this problem, a technology is known in which a phase-modulating spatial light modulator is used to display a phase distribution image (hereinafter sometimes referred to as a phase hologram), modulating only the phase distribution of the light wave and generating a desired three-dimensional light distribution on a plane distant from the spatial light modulator. This method does not require modulation of the light amplitude, and therefore can significantly improve light utilization efficiency.
As methods for creating the phase distribution image, dual phase encoding technology (for example, Non-Patent Documents 2 and 3 listed below) and the linear phase encoding technology described in Patent Document 1 listed below have been proposed. These can generate a desired three-dimensional light distribution with high precision, but the spatial-bandwidth product of the three-dimensional light distribution that can be generated is reduced to 1/4 × 1/4 or 1/8 × 1/8 of the spatial-bandwidth product of the spatial light modulator, which poses a problem in that there is a limit to the degree of freedom of the three-dimensional light distribution that can be generated.

In contrast to these, methods for generating three-dimensional light distributions based on phase holograms, etc., are known to be able to generate the desired three-dimensional light distribution by fully utilizing the spatial-bandwidth product of the spatial light modulator.

Patent Publication No. 2022-34984

Y. Takaki and Y. Tanemoto, “Band-limited zone plates for single-sideband holography,” Appl. Opt., vol. 48, pp. H64-H70 (2009). V. Arrizon, “Improved double-phase computer-generated holograms implemented with phase-modulation devices,” Opt. Lett., vol. 27, pp. 595-597 (2002). D. Pi, J. Liu, and Y. Wang, “Review of computer-generated hologram algorithms for color dynamic holographic three-dimensional display” Light: Science & Applications, vol. 11, 231 (2022).

However, in phase holograms, etc., the light intensity of the three-dimensional light distribution that is generated changes depending on the distribution, and the strength of the light intensity cannot be controlled (for example, as shown in the comparative example in Figure 7 of the present application, in a three-dimensional distribution with many bright spots (for example, the embodiment shown in (d)), light energy is distributed to many bright spots, resulting in a weaker light intensity of the overall image, while in a three-dimensional distribution with few bright spots (for example, the embodiment shown in (a)), relatively more light energy is distributed to each bright spot, resulting in a stronger light intensity of the overall image).
Therefore, in the fields of laser processing and microscopy, it is difficult to irradiate a material or sample with a constant light intensity when the number of bright spots in the three-dimensional light distribution generated over time fluctuates extremely.

Furthermore, in the field of stereoscopic displays, light intensity fluctuates depending on the 3D image being generated. When dynamically generating 3D images, phase holograms or other devices are sequentially switched to generate different 3D images and displayed on a phase-modulation spatial light modulator, but the overall light intensity fluctuates with each frame, making it difficult to display natural 3D moving images.

Furthermore, when a color 3D image is displayed field sequentially on a single phase-modulating spatial light modulator using light sources that emit red, green, and blue light, the relative light intensity values of the red, green, and blue light of the 3D image shift, preventing the colors of the 3D image from being reproduced correctly. While the above-mentioned non-patent document 3 reviews optical systems that generate color 3D moving images, it only suggests using the aforementioned dual phase encoding technology for intensity modulation and does not suggest a method for solving the problem of fluctuations in light intensity according to the generated light distribution in phase holograms, etc.

The present invention has been developed in consideration of the above circumstances, and aims to provide a light distribution generating device that can modulate the light intensity of a three-dimensional light distribution to a desired value, regardless of the form of the three-dimensional light distribution to be generated, using three-dimensional light distribution generation technology based on phase holograms, etc.

The light distribution generating device of the present invention comprises:
a spatial light modulator capable of modulating the phase distribution of light based on a predetermined phase distribution image;
a light source unit that emits light that illuminates the spatial light modulator;
a light intensity modulation unit capable of modulating the intensity of the light emitted from the light source unit;
a signal processing unit that transmits an instruction signal related to aspect information of the predetermined phase distribution image to the light intensity modulation unit in synchronization with a display timing of the predetermined phase distribution image to the spatial light modulator, so that the intensity of the light emitted from the light source unit can be modulated in the light intensity modulation unit based on the aspect information of the predetermined phase distribution image,
The spatial light modulator is characterized in that it is configured to dynamically generate a three-dimensional light distribution having a desired intensity at a position a predetermined distance from the spatial light modulator based on the phase distribution image displayed on the spatial light modulator.
Here, the aspect information of the predetermined phase distribution image can be information about the size of a three-dimensional light distribution generated based on the predetermined phase distribution image.

The light source section may be configured to emit light of a plurality of wavelengths.
The light intensity modulation section may be provided with individual means for performing light intensity modulation on each of the light beams of the plurality of wavelengths.

It is also possible to provide a beam alignment means for coaxially aligning the light beams of the plurality of wavelengths, and a means for performing optical intensity modulation on the light beams of the plurality of wavelengths emitted coaxially from the beam alignment means.
Here, the means for modulating the light intensity can be an electro-optical element.
The means for modulating the light intensity may be an acousto-optic element.

When the means for modulating the light intensity is an acousto-optical element, the acousto-optical element is configured to adjust the frequency and amplitude of ultrasonic waves to be added to the light of the plurality of wavelengths incident on the acousto-optical element, thereby changing the light deflection angle and light intensity of the light emitted from the acousto-optical element,
an aperture is provided downstream of the acousto-optical element, and light of a specific wavelength component is extracted through the aperture, and the extracted light is used to illuminate the spatial light modulator; and the wavelength of the light extracted through the aperture is changed in time series, thereby changing the wavelength of the light illuminating the spatial light modulator in time series;
The spatial light modulator can be configured to dynamically generate a three-dimensional light distribution having a desired intensity at a predetermined distance from the modulator.

According to the light distribution generating device of the present invention, the signal processing unit instructs the light intensity modulation unit on the aspect information of the phase distribution image to be displayed on the spatial light modulator, and based on this, the light intensity modulation unit adjusts the intensity value of the light that illuminates the phase distribution image to be displayed on the spatial light modulator. This makes it possible to modulate the light intensity of the three-dimensional light distribution to a desired value regardless of the aspect of the three-dimensional light distribution to be generated.
In addition, in the fields of laser processing and microscopy, it becomes possible to irradiate a material or sample with light while changing a desired three-dimensional light distribution to a desired light intensity.
Furthermore, in the field of stereoscopic displays, when displaying three-dimensional moving images, it is possible to independently control the intensity of the light illuminating the spatial light modulator regardless of the type of three-dimensional light distribution to be generated, thereby enabling the generation of natural three-dimensional moving images based on phase holograms, etc.

1 is a conceptual diagram illustrating an optical system of a light distribution generating device according to a first embodiment of the present invention. FIG. 10 is a conceptual diagram illustrating an optical system of a light distribution generating device according to a second embodiment of the present invention. FIG. 10 is a conceptual diagram illustrating an optical system of a light distribution generating device according to a third embodiment of the present invention. 1 is a conceptual diagram for explaining design conditions for a phase hologram when a simulation is performed using a light distribution generating device according to an embodiment of the present invention. FIG. 4 shows images of four phase holograms displayed on a spatial light modulator designed in the embodiment shown in FIG. 4 ((a) can generate a light distribution with a width of w = 800 μm, (b) can generate a light distribution with a width of w = 1600 μm, (c) can generate a light distribution with a width of w = 3200 μm, and (d) can generate a light distribution with a width of w = 6400 μm). The images ((a) to (d)) of each phase hologram shown in Figure 5 are displayed on the spatial light modulator of the light distribution generating device of this example (using the configuration of embodiment 1), and the light distribution generated at a position 300 mm away from the display surface of the spatial light modulator is detected by an image sensor. The images ((a) to (d)) of each phase hologram shown in Figure 5 are displayed on the spatial light modulator of the light distribution generating device of the comparative example, and the image shows the result of detecting the light distribution generated at a position 300 mm away from the display surface of the spatial light modulator using an imaging element.

Hereinafter, a light distribution generating device according to an embodiment of the present invention will be described.
(Embodiment 1)
First, the configuration of a light distribution generating device 100 according to the first embodiment will be described with reference to FIG.
The light distribution generating device 100 according to the first embodiment includes a (phase modulation type) spatial light modulator 5 capable of modulating the phase distribution of a light wave, one light source 1 that illuminates the spatial light modulator 5, a light intensity modulation unit 6 that can modulate the intensity of the illumination light emitted from the light source 1, and a signal processing unit 7 that controls the intensity of the illumination light in a time series while synchronizing the timing of displaying a phase distribution image on the spatial light modulator 5 with the timing of transmitting an aspect information signal related to the phase distribution image to the light intensity modulation unit 6 (and the timing of modulating the intensity of the illumination light in the light intensity modulation unit 6). The signal processing unit 7 is configured to adjust the intensity value of the light that illuminates the spatial light modulator 5 in the light intensity modulation unit 6, based on the aspect of the phase distribution image displayed on the spatial light modulator 5, so that a three-dimensional light wave distribution having a desired intensity is dynamically generated at a predetermined distance from the spatial light modulator 5. In addition to the above configuration, the light distribution generating device 100 according to the first embodiment also includes a spatial filter 2 and a lens (converging lens) 3 that convert the light emitted from the light intensity modulation unit 6 into a desired plane wave (or a desired spherical wave is also possible). Furthermore, the light distribution generating device 100 includes a beam splitter 4 that reflects the light converted into a plane wave by the spatial filter 2 and the lens 3 toward the spatial light modulator 5, and transmits the light that carries information about the phase distribution image reflected by the spatial light modulator 5. A desired three-dimensional distribution 8 is formed at a predetermined position in front of the spatial light modulator 5 by the light that has transmitted through the beam splitter 4 and carries information about the phase distribution image.

That is, the light distribution generating device 100 according to the first embodiment basically has the following functions (1) to (4).
(1) The light intensity of the illumination light to the phase modulation type spatial light modulator 5 is modulated by the light intensity modulation unit 6 .
(2) Information on the desired light intensity (for example, stored in a memory unit not shown) is provided for each (according to) the form of the phase distribution image to be displayed on the phase modulation type spatial light modulator 5 (such as size information of the three-dimensional distribution to be generated).
(3) An instruction signal from the signal processing unit 7 is sent to the light intensity modulation unit 6 so that the timing of displaying the phase distribution image on the spatial light modulator 5 and the timing of modulating the intensity of the light illuminating the spatial light modulator 5 in the light intensity modulation unit 6 are synchronized.
(4) At the same time as sequentially switching the phase distribution image displayed on the spatial light modulator 5, the intensity of the light illuminating the spatial light modulator 5 is modulated in the light intensity modulation unit 6 based on the light intensity information added to the phase distribution image (the aspect of the phase distribution image (size information of the three-dimensional distribution to be generated)).

The configuration of each part of the light distribution generating device 100 according to the first embodiment will be described in more detail below.
As the light source 1, it is preferable to use a highly coherent light source capable of reproducing a hologram, such as a laser or a light emitting diode, or a partially coherent light source.
An electro-optical element (EOM) or an acousto-optical element (AOM) is suitable as the light intensity modulation unit 6 to which the light emitted from the light source 1 is incident. Any of these optical elements can continuously modulate the light intensity of the incident light from 0 to 1 (maximum intensity). Furthermore, any of these optical elements can modulate the light intensity at high speeds equal to or faster than the frame rate of the phase-modulation type spatial light modulator 5.

In embodiment 1 shown in Figure 1, a spatial filter 2 and a lens 3 are provided to convert the light emitted from the light intensity modulation unit 6 into a plane wave (or a spherical wave), but a beam expander can also be used in place of the spatial filter 2 and lens 3.

In the first embodiment shown in FIG. 1, a reflective phase modulation spatial light modulator 5 made of an LCOS or DMD is used, but it is also possible to use a transmissive spatial light modulator instead, in which case the beam splitter 4 is not necessary.
When a phase hologram or the like created from the complex amplitude distribution to be generated is displayed on the spatial light modulator 5, only the phase distribution (the amplitude distribution is not modulated) of incident light consisting of a plane wave or the like irradiated onto the spatial light modulator 5 is modulated. The light phase-modulated by the spatial light modulator 5 propagates to a position (surface) a predetermined distance in front of the spatial light modulator 5, and generates a desired three-dimensional light distribution based on the phase hologram or the like displayed on the spatial light modulator 5. Note that by configuring the light phase-modulated by the spatial light modulator 5 to be Fourier-transformed using a lens (not shown) and then generating a three-dimensional light distribution, it is possible to generate a desired three-dimensional light distribution based on the phase hologram or the like at a position (surface) closer in front of the spatial light modulator 5.

Furthermore, digital information relating to light intensity values is added to the data of the phase hologram, etc., and when the signal processing unit 7 displays the phase hologram, etc. on the spatial light modulator 5, it refers to the digital information of the light intensity values added to the data of the phase hologram, etc., and sends an instruction signal based on this digital information to the light intensity modulation unit 6, which synchronizes with the switching of the display of the phase hologram, etc. on the spatial light modulator 5, and the light intensity modulation unit 6 modulates the intensity value of the light from the light source 1 based on the instruction signal.
As the digital information regarding the light intensity values, for example, the light intensity value information can be added as metadata of the image data of a phase hologram (the phase values 0 to 2π can be quantized according to the number of gradations that can be displayed by a spatial light modulator and expressed as a grayscale image. For example, see FIG. 5. When a light source of three colors, RGB, is used, it is expressed as a three-color channel image).

It is also possible to add pixels around the image data of the phase hologram and store light intensity information in those pixels (in this case, the spatial light modulator 5 removes the surrounding pixels to which the image data of the phase hologram has been added and displays the phase hologram).
Furthermore, even if the initial phase of the phase hologram changes, the three-dimensional light distribution does not change, so information on the light intensity value may be added as the amount of shift in the initial phase of the phase hologram.

In addition, as a mode of providing digital information regarding the light intensity value, as described above, in addition to the size of the three-dimensional light distribution generated based on the phase hologram displayed on the spatial light modulator 5, the light intensity value for the phase hologram can be calculated, for example, from the number of bright spots in the three-dimensional light distribution to be generated and the intensity of each bright spot.

Furthermore, if the optical system contains a large amount of aberration or placement error, using the analytical calculation formula (1) above may result in a discrepancy between the theoretical value and the actual light intensity value. Therefore, it is possible to generate a three-dimensional light distribution from a phase hologram in the optical system in advance, adaptively change the light intensity, and create a lookup table of light intensity values that can be used to adjust the phase hologram, and then refer to this.

(Embodiment 2)
Next, the configuration of a light distribution generating device 110 according to the second embodiment will be described with reference to FIG.
In the light distribution generating device 110 according to the second embodiment, a plurality of light sources 11A, 11B, and 11C (three in FIG. 2 ) are provided, each emitting illumination light of a different wavelength. Light intensity modulation units 16A, 16B, and 16C are provided corresponding to the light sources 11A, 11B, and 11C, respectively. Furthermore, the device is configured to add intensity information for light of each wavelength of the illumination light to each phase distribution image displayed on the spatial light modulator 15.

The light distribution generating device 110 according to the second embodiment shown in FIG. 2 has many similar configurations to the light distribution generating device 100 according to the first embodiment. Therefore, components corresponding to the components of the light distribution generating device 100 according to the first embodiment are assigned reference numerals that are 10 larger than the reference numerals assigned to the components of the light distribution generating device 100 according to the first embodiment, and detailed descriptions of components that overlap with those of the first embodiment will be omitted.
2, the light intensity from each of the light sources 11A, 11B, and 11C is controlled independently by light intensity modulation units 16A, 16B, and 16C provided corresponding to the light sources 11A, 11B, and 11C. That is, a signal line is connected from the signal processing unit 17 to each of the light intensity modulation units 16A, 16B, and 16C so that instruction signals can be sent individually to each of the light intensity modulation units 16A, 16B, and 16C.

The light emitted from each of the light intensity modulation units 16A, 16B, and 16C is propagated as a single light beam along an aligned line by a mirror 19A and a dichroic mirror (or dichroic prism) 19B or 19C. The light propagating along the same axis is then converted into a plane wave (or spherical wave) by an optical spatial filter 12 and a lens 13 (or a beam expander), and illuminates a phase-modulating spatial light modulator 15.
The phase modulation type spatial light modulator 15 is a reflective type, and light is incident on and emitted from the spatial light modulator 15 via a beam splitter 14, similar to the first embodiment.

When generating a three-dimensional light distribution for each wavelength component using a field sequential method in which the screen is divided into multiple regions and phase holograms or the like are sequentially displayed in the multiple regions, light intensity information for each wavelength based on aspect information of the phase hologram or the like to be displayed on the spatial light modulator 15 (information about the aspect (size, etc.) of the three-dimensional light distribution generated based on this phase hologram or the like) is pre-added to the digital information of the phase hologram or the like. When the phase hologram or the like is displayed on the spatial light modulator 15, the light intensity information for each wavelength added to the digital information of the phase hologram or the like is referenced, and the light intensity of the corresponding wavelength component is modulated in light intensity modulation units 16A, 16B, and 16C in synchronization with the display timing.

(Embodiment 3)
Next, the configuration of a light distribution generating device 120 according to the third embodiment will be described with reference to FIG.
In the light distribution generating device 120 according to the third embodiment, a plurality of light sources 21A, 21B, and 21C (three in FIG. 3 ) are provided, each emitting illumination light of a different wavelength, whereas the light intensity modulation unit 26 is provided with a single acousto-optic element that aligns the light from each of the light sources 11A, 11B, and 11C to collect and propagate the collected light on a coaxial line, and then inputs the collected light to modulate the light intensity for each wavelength component.

As described above, in the light distribution generating device 120 according to the third embodiment, an acousto-optic element is used as the light intensity modulation unit 26. This acousto-optic element modulates light using the diffraction phenomenon, and therefore the deflection angle varies depending on the wavelength of the incident light, and the spatial separation distance between the output light beams of each wavelength increases according to the propagation distance from the output end of the light intensity modulation unit 26.
In other words, by using the aperture 31 to extract only light of the desired wavelength at a position (plane) where light of different wavelengths is sufficiently spatially separated, light of a specific wavelength component can be irradiated onto the phase-modulating spatial light modulator 25.

As a result, in the light intensity modulation section 26 consisting of an acousto-optical element, by setting the frequency of the excitation ultrasound to a predetermined value, it is possible to select light of a wavelength that can pass through the opening 31, and by setting the amplitude of the ultrasound to a predetermined value, it is possible to set the intensity of light of a wavelength that can pass through the opening 31 to a desired value.
If the aperture diameter of the spatial filter 22 (or beam expander) can be formed small enough to filter out the desired wavelength component, the aperture 31 may be omitted.
Comparing the light distribution generating device 120 of embodiment 3 with the light distribution generating device 110 of embodiment 2, regardless of the number of light sources, illumination light for the spatial light modulator 25 of the desired intensity can be generated using a single light modulator element (such as an acousto-optical element (AOM) or an electro-optical element (EOM)), thereby making it possible to make the light distribution generating device more compact.
The other components are configured in substantially the same manner as those in the second embodiment.

The effect of the light distribution generating device according to the example of the present invention, which employs the configuration of the light distribution generating device according to the first embodiment shown in FIG. 1, was verified using the method described below.
That is, the phase hologram to be displayed on the phase modulation type spatial light modulator 45 was designed under the conditions shown in FIG.
The phase-modulating spatial light modulator 45 had a pixel pitch of 12.5 μm and a pixel count of 512 × 512, and was illuminated with laser light of 633 nm wavelength. Phase holograms capable of generating three-dimensional light distributions 48 with widths w of 800 μm, 1600 μm, 3200 μm, and 6400 μm on a surface 300 mm away from the phase-modulating spatial light modulator 45 were designed using iterative calculations based on the Gerchberg-Saxton algorithm (iterative Fourier transform algorithm or ping-pong algorithm). The number of iterations used in designing all phase holograms was 500.

The four phase holograms designed as described above are shown in Figure 5 ((a) when the width w of the generated three-dimensional light distribution 48 is 800 μm, (b) when it is 1600 μm, (c) when it is 3200 μm, and (d) when it is 6400 μm, at a position (plane) 300 mm away from the spatial light modulator 45).

(Example)
Each of the phase holograms shown in Figures 5(a) to 5(d) was displayed on the phase-modulation spatial light modulator 5 in the light distribution generating device 100 of Figure 1 according to embodiment 1, and the three-dimensional light distribution generated at a position (plane) 300 mm in front of the spatial light modulator 5 was detected by an image sensor (not shown). Note that the light intensity modulation unit 6 shown in Figure 1 modulated the light intensity of the illumination light for each phase hologram, and illuminated the phase-modulation spatial light modulator 5 under the condition that the light distribution of Figure 6(d) was not underexposed.
The results are shown in Figure 6 ((a) when the width w of the three-dimensional light distribution 8 generated at a position (plane) 300 mm away from the spatial light modulator 5 is 800 μm, (b) when it is 1600 μm, (c) when it is 3200 μm, and (d) when it is 6400 μm).

(Comparative Example)
Each of the phase holograms shown in Figures 5(a) to 5(d) was displayed on the phase-modulation spatial light modulator 5 in the light distribution generating device 100 of Figure 1 according to embodiment 1, and the three-dimensional light distribution generated at a position (plane) 300 mm in front of the spatial light modulator 5 was detected by an image sensor (not shown). Note that the light intensity modulation unit 6 shown in Figure 1 was not operated, and the light from the light source 1 was allowed to pass as is, and the phase-modulation spatial light modulator 5 was illuminated with light of the same intensity under the condition that the light distribution of Figure 7(a) would not be overexposed.
The results are shown in Figure 7 ((a) when the width w of the three-dimensional light distribution 8 generated at a position (plane) 300 mm away from the spatial light modulator 5 is 800 μm, (b) when it is 1600 μm, (c) when it is 3200 μm, and (d) when it is 6400 μm).

(Verification results)
In the comparative example, as is clear from Figure 7, the larger the size of the three-dimensional light distribution to be generated, the more dispersed the light energy of the laser light illuminating the phase modulation type spatial light modulator 5 becomes, and the weaker the light intensity becomes.
In contrast to this, in this embodiment, as is clear from FIG. 6, it is clear that the light intensity of the three-dimensional light distribution to be generated can be adjusted to a substantially constant value regardless of its size.

(Modifications)
The light distribution generating device of the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, the focal length, size, performance, and other characteristics of each component such as a lens can be selected as appropriate.
Furthermore, in the third embodiment, one acousto-optical element (AOM) is used as the light intensity modulation section 26, but it is also possible to use an electro-optical element (EOM) instead.
Electro-optical elements electrically control the intensity of illumination light irradiating a spatial light modulator by using the electro-optical effect of crystals such as lithium niobate. Although the intensity modulation operation is somewhat more complicated than that of acousto-optical elements, it is possible to perform modulation in the same way as acousto-optical elements.

Furthermore, in the above-described second and third embodiments, the light distribution generating device is configured on the premise of using a light source that emits light of one wavelength, but instead of this configuration, a type that emits light of multiple wavelengths from one light source may be used.
Furthermore, in the above embodiment, a beam splitter (BS) is used to separate the incident light of the reflective spatial light modulator from the outgoing light from this reflective spatial light modulator, but a polarizing beam splitter (PBS) may also be used to separate the incident light and outgoing light, thereby improving the light utilization efficiency.
Furthermore, the light emitted from the light source may be laser light having a wavelength not only in the visible range but also in the infrared or ultraviolet range, and light having multiple wavelengths may be selected not only from the three color lights of R, G, and B, but also from any other multiple wavelengths.

1, 11A, 11B, 11C, 21A, 21B, 21C Light source 2, 12, 22 Spatial filter 3, 13, 23 Lens 4, 14, 24 Beam splitter 5, 15, 25, 45 (Phase modulation type) spatial light modulator 6, 16A, 16B, 16C, 26 Light intensity modulation unit 7, 17, 27 Signal processing unit 8, 18, 28, 48 (Desired) three-dimensional light distribution 100, 110, 120 Light distribution generating device

Claims (8)

a spatial light modulator capable of modulating the phase distribution of light based on a predetermined phase distribution image;
a light source unit that emits light that illuminates the spatial light modulator;
a light intensity modulation unit capable of modulating the intensity of the light emitted from the light source unit;
a signal processing unit that transmits an instruction signal related to aspect information of the predetermined phase distribution image to the light intensity modulation unit in synchronization with a display timing of the predetermined phase distribution image to the spatial light modulator, so that the intensity of the light emitted from the light source unit can be modulated in the light intensity modulation unit based on the aspect information of the predetermined phase distribution image,
A light distribution generating device characterized in that it is configured to dynamically generate a three-dimensional light distribution having a desired intensity at a position a predetermined distance from the spatial light modulator based on a phase distribution image displayed on the spatial light modulator. The light distribution generating device described in claim 1, characterized in that the aspect information of the predetermined phase distribution image is information about the size of the three-dimensional light distribution generated based on the predetermined phase distribution image. The light distribution generating device described in claim 1, characterized in that the light source unit is configured to emit light of multiple wavelengths. The light distribution generating device described in claim 3, characterized in that the light intensity modulation unit is equipped with means for individually performing light intensity modulation on each of the multiple types of wavelength light. The light distribution generating device described in claim 3, characterized in that it comprises a beam alignment means for coaxially aligning the light of the multiple wavelengths, and a means for performing light intensity modulation on the light of the multiple wavelengths emitted coaxially from the beam alignment means. The light distribution generating device described in claim 5, characterized in that the means for performing light intensity modulation is an electro-optical element. The light distribution generating device described in claim 5, characterized in that the means for performing light intensity modulation is an acousto-optic element. When the means for modulating the light intensity is an acousto-optical element, the acousto-optical element is configured to adjust the frequency and amplitude of ultrasonic waves to be added to the light of the plurality of wavelengths incident on the acousto-optical element, thereby changing the light deflection angle and light intensity of the light emitted from the acousto-optical element,
an aperture is provided downstream of the acousto-optical element, and light of a specific wavelength component is extracted through the aperture, and the extracted light is used to illuminate the spatial light modulator; and the wavelength of the light extracted through the aperture is changed in time series, thereby changing the wavelength of the light illuminating the spatial light modulator in time series;
8. The light distribution generating device according to claim 7, wherein a three-dimensional light distribution having a desired intensity is dynamically generated at a position a predetermined distance from the spatial light modulator.