Phase modulation device

Abstract

A phase modulator according to an embodiment of the present disclosure includes: a phase modulation element having a plurality of pixels and capable of modulating a phase of light from a light source; a generation unit capable of generating first data relating to a phase modulation amount of each of the pixels; and an adjustment unit capable of adjusting the first data based on a wavelength of light from the light source such that the phase modulation range includes the reference phase value. The phase modulation element may modulate a phase of light from the light source based on the first data adjusted by the adjustment unit.

Description

Technical Field

[0001] The present disclosure relates to a phase modulation device. Background Art

[0002] A liquid crystal display device has been proposed which includes a glass substrate coated with an antireflection film and prevents multiple reflections in a liquid crystal layer (Patent Document 1). In addition, a phase modulation device including liquid crystal has also been proposed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. H5-66393 Summary of the invention

[0006] A phase modulation device is desired to suppress degradation of image quality.

[0007] It is desirable to provide a phase modulation device capable of suppressing degradation of image quality.

[0008] A phase modulation device according to an embodiment of the present disclosure includes: a phase modulation element including a plurality of pixels and configured to modulate the phase of light from a light source; a generation unit configured to generate first data on a phase modulation amount for each of the plurality of pixels; and an adjustment unit configured to adjust the first data so that a phase modulation range includes a reference phase value based on a wavelength of light from the light source. The phase modulation element is configured to modulate the phase of the light from the light source based on the first data adjusted by the adjustment unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 : is a diagram showing an example of a schematic configuration of a phase modulation device according to the first embodiment of the present disclosure.

[0010] Figure 2 : is a diagram for describing a configuration example of a phase modulation element according to the first embodiment of the present disclosure.

[0011] Figure 3 : is a diagram showing an example of the relationship between the voltage applied to the pixel of the phase modulation element according to the first embodiment of the present disclosure and the phase modulation amount.

[0012] Figure 4 : is a diagram for describing an example of signal processing of the phase modulation device according to the first embodiment of the present disclosure.

[0013] Figure 5 : is a diagram showing a configuration example of a phase modulation element according to the first embodiment of the present disclosure.

[0014] Figure 6 : is a diagram showing another configuration example of the phase modulation element according to the first embodiment of the present disclosure.

[0015] Figure 7 : is a diagram for describing an exemplary setting of a phase adjustment range by the phase modulation device according to the first embodiment of the present disclosure.

[0016] Figure 8 : is a diagram for describing an exemplary setting of a phase adjustment range by the phase modulation device according to the first embodiment of the present disclosure.

[0017] Fig. 9 : is a diagram showing an example of a schematic configuration of a phase modulation device according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] Some embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be noted that the description is made in the following order.

[0019] 1. First Implementation

[0020] 2. Second Implementation

[0021] 3. Modifications

[0022] <1. First Embodiment>

[0023] Figure 1 1 is a diagram showing an example of a schematic configuration of a phase modulation device according to a first embodiment of the present disclosure. The phase modulation device 1 is a device configured to modulate the phase of light. The phase modulation device 1 controls the phase of light using a phase modulation element. The phase modulation device 1 can control the wavefront of light to output light of an arbitrary pattern. The phase modulation device 1 can be applied to various display devices and optical devices. The phase modulation device 1 can be applied to, for example, a 3D display device, a laser processing device, a fundus examination device, an astronomical observation device, and the like.

[0024] The phase modulation device 1 includes a signal processing unit 10, a driving unit 50 and a phase modulation element 100. Figure 1 As shown, the phase modulation device 1 may include a light source 60. The signal processing unit 10 is configured to perform signal processing. The signal processing unit 10 includes, for example, a processor and a memory such as a ROM or a RAM, and performs signal processing (information processing) based on a program. The signal processing unit 10 may also be referred to as a signal processing circuit. The signal processing unit 10 may also serve as a control unit for controlling each part of the phase modulation device 1. For example, the signal processing unit 10 may provide a signal for controlling the driving unit 50 to the driving unit 50, thereby controlling the operation of the driving unit 50.

[0025] The signal processing unit 10 includes a generating section 11, a setting section 12, and an adjusting section 13. The generating section 11 is configured to generate data on the phase modulation amount (hereinafter, referred to as phase distribution data). The phase distribution data (phase distribution information) is data on the phase modulation amount of each pixel of the phase modulation element 100. The phase distribution data is data on the distribution of the phase modulation amount set in the phase modulation element 100. In other words, the phase distribution data is data on the magnitude of the voltage (potential difference) between the electrodes of the pixels provided to the phase modulation element 100. The generating section 11 is a phase distribution generating section configured to generate the phase distribution data.

[0026] The generating section 11 generates phase distribution data D1 based on image data (image signal) received from the outside, for example. The generating section 11 can generate the phase distribution data D1 by performing light propagation calculation using the image data. The generating section 11 calculates the phase modulation amount of each pixel required for display (reproduction) of an image (for example, a hologram reproduction image) based on the image data, thereby generating phase distribution data D1 about the phase modulation amount of each pixel. The generating section 11 can also be referred to as a calculating section configured to calculate phase distribution. The generating section 11 outputs the phase distribution data D1 thus generated to the adjusting section 13.

[0027] The setting section 12 is configured to set a setting range of the phase modulation amount of the phase modulation element 100. The setting section 12 generates data on the setting range of the phase modulation amount (hereinafter, referred to as phase setting range data). The phase setting range data is data on a settable range of the phase modulation amount of the phase modulation element 100. The setting section 12 is a phase modulation range setting section configured to set the phase modulation range.

[0028] The setting section 12 determines, for example, a median value, an upper limit value, a lower limit value, etc. of a setting range of the phase modulation amount, thereby generating phase setting range data indicating the median value, the upper limit value, the lower limit value, etc. of the setting range. The setting section 12 may also be referred to as a determination section configured to determine the setting range of the phase modulation amount of the phase modulation element 100. The setting section 12 outputs the phase setting range data thus generated to the adjustment section 13.

[0029] The adjustment section 13 is configured to adjust the phase distribution data. As described later, the adjustment section 13 adjusts the phase distribution data D1 so that the phase modulation range includes a phase value (reference phase value) based on the wavelength of the light from the light source 60. The adjustment section 13 is a phase distribution adjustment section configured to adjust the phase distribution. The adjustment section 13 adjusts (corrects) the phase modulation amount of each pixel represented by the phase distribution data D1 based on the reference phase value. The adjustment section 13 may also be referred to as a correction section configured to correct the phase distribution data. The adjustment section 13 may generate phase distribution data D2 about the distribution of the phase modulation amount after adjustment, and may output the phase distribution data D2 to the driving section 50.

[0030] The driving section 50 is configured to drive the phase modulation element 100. The driving section 50 is a driving device (driving circuit), and can control the operation of the phase modulation element 100. For example, the driving section 50 is configured to control the voltage to the phase modulation element 100. The driving section 50 can supply a voltage for driving each pixel of the phase modulation element 100 to the phase modulation element 100, thereby controlling the phase modulation to be performed by the phase modulation element 100.

[0031] exist Figure 1 In the example shown, the phase distribution data D2 adjusted by the adjustment section 13 is received by the drive section 50. The drive section 50 determines the magnitude (set value) of the voltage to be supplied to each pixel of the phase modulation element 100 based on the phase distribution data D2, and supplies the voltage to each pixel of the phase modulation element 100. For example, the voltage to be supplied to each pixel of the phase modulation element 100 is controlled so as to obtain the distribution of the phase modulation amount represented by the phase distribution data D2, which allows the phase modulation amount of each pixel to be adjusted.

[0032] The phase modulation element 100 is an element configured to modulate the phase of incident light. The phase modulation element 100 is a liquid crystal phase modulation element, and uses liquid crystal to control the phase of light from the light source 60. It should be noted that the phase modulation element 100 may be a transmissive liquid crystal element or a reflective liquid crystal element.

[0033] Figure 2 1 is a diagram for describing a configuration example of a phase modulation element according to a first embodiment. The phase modulation element 100 includes a plurality of pixels P and is configured to control the phase of light of each pixel P. In the phase modulation element 100, a plurality of pixels P are arranged in a two-dimensional manner. Figure 1 As shown, the phase modulation element 100 includes a first substrate 101 , a second substrate 102 , and a liquid crystal layer 110 .

[0034] The first substrate 101 and the second substrate 102 are fixed by a sealing material not shown, sandwiching the liquid crystal layer 110. The paired first substrate 101 and the second substrate 102 are spaced apart from each other in the stacking direction. It should be noted that, as required, each polarizer may be arranged above the first substrate 101 and below the second substrate 102.

[0035] The first substrate 101 is a transparent substrate that transmits light, such as a glass substrate. A first electrode 20a is provided on the first substrate 101. The second substrate 102 is provided opposite to the first substrate 101. The second substrate 102 is, for example, a glass substrate, a semiconductor substrate (such as a silicon substrate), etc. A second electrode 20b is provided on the second substrate 102. The second electrode 20b is arranged opposite to the first electrode 20a with a portion of the liquid crystal layer 110 sandwiched therebetween.

[0036] The first electrode 20a is a transparent electrode including, for example, indium tin oxide (ITO). The first electrode 20a is an electrode common to a plurality of pixels P, and may also be referred to as a counter electrode (or a common electrode).

[0037] For example, the second electrode 20b includes a transparent material such as ITO. In addition, the second electrode 20b may also include other metal materials such as aluminum (Al). The second electrode 20b is an electrode provided for each pixel P, also referred to as a pixel electrode. In addition, devices including transistors and wiring are formed on the second substrate 102. The second substrate 102 may be provided with a circuit for driving each pixel P.

[0038] The liquid crystal layer 110 is a layer including a plurality of liquid crystal molecules, and is disposed between the first substrate 101 and the second substrate 102. The liquid crystal layer 110 is sealed between the first substrate 101 and the second substrate 102 by a sealing material. The liquid crystal molecules of the liquid crystal layer 110 having dielectric anisotropy respond to the voltage applied between the first electrode 20a and the second electrode 20b, thereby achieving control of the orientation of the liquid crystal molecules.

[0039] The phase modulation element 100 further includes an anti-reflection film 40 and an orientation film 30 (in Figure 2 In the embodiment, the first alignment film 30a and the second alignment film 30b are provided. For example, the anti-reflection film 40 includes a metal oxide. Figure 2 In the example shown, the anti-reflection film 40 is provided between the first electrode 20a and the first alignment film 30a and reduces (suppresses) reflection. The anti-reflection film 40 may be provided between the second electrode 20b and the second alignment film 30b. It should be noted that the anti-reflection film 40 may not be provided in the phase modulation element 100.

[0040] The alignment film 30 can align the liquid crystal molecules of the liquid crystal layer 110 in a specific direction. The alignment film 30 is a film (layer) capable of controlling the alignment of the liquid crystal molecules. The alignment film 30 is, for example, a film formed by oblique vapor deposition (oblique vapor deposition film), a polymer, or the like.

[0041] exist Figure 2 In the example shown, the first alignment film 30a is located between the liquid crystal layer 110 and the first electrode 20a, and is disposed on the first electrode 20a. The second alignment film 30b is located between the liquid crystal layer 110 and the second electrode 20b, and is disposed on the second electrode 20b. The liquid crystal molecules of the liquid crystal layer 110 are maintained in a tilted state by the first alignment film 30a and the second alignment film 30b. That is, the liquid crystal molecules of the liquid crystal layer 110 are each given a predetermined pre-tilt angle (tilt angle).

[0042] In the phase modulation element 100, the electric field in the liquid crystal layer 110 changes according to the voltage supplied between the first electrode 20a and the second electrode 20b, which changes the orientation of the liquid crystal molecules. By controlling the voltage supplied to the second electrode 20b of each pixel P, the orientation of the liquid crystal molecules can be adjusted for each pixel P, thereby changing the refractive index and the optical path length.

[0043] Light incident on each pixel P of the phase modulation element 100 is phase-modulated according to the tilt amount of the liquid crystal molecules of each pixel P and then emitted. The phase modulation element 100 causes each pixel P to have a different phase delay relative to the incident light, thereby transmitting light having a desired wavefront.

[0044] Figure 2 The multiple reflected light beam W1 shown in FIG. 1 schematically represents the multiple reflected light beam generated in the case where the phase modulation element 100 is a reflective liquid crystal element. In addition, the multiple reflected light beam W2 schematically represents the multiple reflected light beam that will be generated in the case where the phase modulation element 100 is a transmissive liquid crystal element. Even in the case where the phase modulation element 100 includes the anti-reflection film 40, the multiple reflected light beams are generated by multiple reflections between the first substrate 101 and the second substrate 102, depending on the wavelength of the incident light, etc., which may cause interference of the wavefront of the emitted light.

[0045] In order to solve this problem, the phase modulation device 1 according to the present embodiment adjusts the phase distribution data so that the phase modulation range of each pixel P of the phase modulation element 100 includes a reference phase value, thereby performing phase modulation of light using the phase modulation element 100. The reference phase value is a phase modulation amount set so that the light beams multiply reflected in the phase modulation element 100 have the same corresponding phases as each other. In the present embodiment, the phase difference between the multiply reflected light beams can be reduced. This makes it possible to suppress the interference of the wavefront caused by the multiply reflected light beams.

[0046] Figure 3 : is a diagram showing an example of the relationship between the voltage applied to the pixel of the phase modulation element according to the first embodiment and the phase modulation amount. Figure 3 In FIG. 1 , the applied voltage is represented by the horizontal axis and the phase modulation amount is represented by the vertical axis. Figure 3 The reference phase value θc shown in is determined based on the wavelength of light incident on the phase modulation device 100. In the present embodiment, the reference phase value θc is set by the setting section 12 or the adjustment section 13 based on the wavelength of light from the light source 60, and is, for example, 0π or 2π.

[0047] Figure 3 The phase modulation range R1 shown in FIG. 1 is the phase modulation range indicated by the above-mentioned phase setting range data, and is the setting range of the phase modulation amount of the phase modulation element 100. The setting section 12 sets the range including the reference phase value θc in the settable range of the phase modulation amount of the phase modulation element 100 as the phase modulation range R1, and generates the phase setting range data indicating the phase modulation range R1.

[0048] The phase modulation range R2 is the phase modulation range indicated by the above-mentioned phase distribution data D2, and is the range of the phase modulation amount required to display an image. The adjustment section 13 performs shift adjustment of the phase distribution data D1 so that the phase modulation range indicated by the phase distribution data D1 generated by the generation section 11 includes the reference phase value θc. Figure 3 In the embodiment shown in , the phase modulation range represented by the phase distribution data D2 generated by the shift adjustment is the phase modulation range R2 including the reference phase value θc.

[0049] The driving section 50 supplies a voltage to each pixel P of the phase modulation element 100, thereby obtaining a phase distribution represented by the phase distribution data D2. Since the phase modulation amount of the phase modulation element 100 is a value within a range including the reference phase value θc, it is possible to reduce the phase difference between the light beams multiply reflected in the phase modulation element 100. This makes it possible to suppress the occurrence of interference of wavefronts caused by the multiply reflected light beams.

[0050] In one example, if Figure 4 As shown, the adjustment section 13 according to the present embodiment performs offset adjustment of the phase modulation amount for each pixel P. The adjustment section 13 may adjust the phase distribution data D1 to reduce the difference between the phase modulation amount of each pixel P and the reference phase value θc. The adjustment section 13 may perform the offset adjustment of the phase modulation amount to reduce the sum S1 of values ​​obtained by squaring the difference between the phase modulation amount Ψ of each pixel P and the reference phase value θc (see the following expression (1)).

[0051] [Expression 1]

[0052]

[0053] In this case, the adjustment section 13 can adjust the phase modulation amount Ψ so that the sum S1 is minimized. This makes it possible to reduce the difference between the phase modulation amount Ψ of each pixel P and the reference phase value θc, and thus effectively suppress the interference of the wavefront caused by the multiple reflected light beams. Therefore, the image quality of the image can be improved. It should be noted that when the phase modulation amount is adjusted within the phase modulation range R1, the adjustment section 13 can perform a process of wrapping (folding back) the phase modulation amount based on the phase modulation range R1.

[0054] In one example, the generation unit 11 of the phase modulation device 1 is configured to generate the phase distribution data D1 by performing a light propagation calculation once. The generation unit 11 can generate the phase distribution data D1 by calculating the light propagation between the image plane and the reproduction plane of the phase modulation device 100 only once under the condition that the uniform phase is set as the initial phase of the reproduction plane, the reproduction plane being the image plane formed by the phase-modulated light.

[0055] In this case, the generation unit 11 may adopt Sommerfeld diffraction integral, angular spectrum method, Fresnel diffraction, etc. as the propagation calculation method. In addition, for example, the generation unit 11 may adopt a dual phase (DP) method, a complex field encoding (CFE) method, etc. as a method of converting amplitude information obtained by the light propagation calculation into phase information.

[0056] The generation unit 11 can bias the phase distribution of the phase distribution data D1 through the above-mentioned light propagation calculation, thereby reducing the influence of multiple reflections on image quality. In addition, since the light propagation calculation is performed in a single step, the calculation speed can be maintained at a high speed.

[0057] It should be noted that the generation unit 11 can generate the phase distribution data D1 by performing the light propagation calculation multiple times. The generation unit 11 can use the Gerchberg-Saxton method, the Wirtinger holographic method, the stochastic gradient descent (SGD) method, etc. as the propagation calculation method. The generation unit 11 can optimize the phase distribution on the image plane of the phase modulation element 100 by performing the light propagation calculation at least twice.

[0058] In the case of performing multiple light propagation calculations, the phase distribution of the phase distribution data D1 can also be deviated, thereby reducing the impact of multiple reflections on image quality. In addition, the degree of phase distribution can be controlled by the initial phase set during the light propagation calculation, thereby increasing the degree of freedom of setting. Therefore, it is expected to improve image quality.

[0059] Figure 5 : is a diagram showing a configuration example of a phase modulation element according to the first embodiment. Figure 5 The example in which the phase modulation element 100 is a reflective liquid crystal element is shown. When phase modulation is not performed in the phase modulation element 100, the optical path length L between the first electrode 20a and the second electrode 20b can be calculated using the refractive index n of each layer. k and the thickness of each layer d k It is represented by the following expression (2).

[0060] [Expression 2]

[0061]

[0062] The total phase quantity θ at a specific wavelength λ all The change amount Δn of the refractive index of the liquid crystal layer 110 and the thickness d of the liquid crystal layer 110 can be expressed by the following expression (3).

[0063] [Expression 3]

[0064]

[0065] When the first electrode 20a has a refractive index r1, the second electrode 20b has a refractive index r2, and the incident wave has a phase α, a combined wave Φ1 of the multi-reflected light beam W1 can be expressed by the following expression (4).

[0066] [Expression 4]

[0067]

[0068] From the above-mentioned expressions (3) and (4), the following expression (5) is obtained. Note that in expression (5), m is an integer.

[0069] [Expression 5]

[0070]

[0071] In the case where the optical path length (L+Δnd) between the substrates is an integral multiple of the half wavelength of the incident light, the combined wave Φ1 is a combination of waves having respective wavefronts identical to each other. This makes it possible to prevent the occurrence of interference of wavefronts.

[0072] In the case where the phase modulation element 100 is a reflective liquid crystal element, the setting section 12 (or the adjustment section 13) of the phase modulation device 1 can set such a phase modulation amount of the phase modulation element 100 that allows the optical path length between the first substrate 101 and the second substrate 102 to be an integral multiple of the half wavelength of the light from the light source 60 as the reference phase value θc. The above-mentioned offset adjustment of the phase modulation amount based on the reference phase value θc reduces the phase difference between the multiple reflected light beams. Therefore, it is possible to prevent the interference of the wavefront caused by the multiple reflected light beams, and it is possible to suppress the degradation of the image quality.

[0073] Figure 6 is a diagram showing another configuration example of the phase modulation element according to the first embodiment. Figure 6 The example in which the phase modulation element 100 is a transmissive liquid crystal element is shown. In this case, the total phase amount θ at a certain wavelength λ all It can be expressed by the following expression (6).

[0074] [Expression 6]

[0075]

[0076] Further, the combined wave Φ2 of the multiple reflected light beam W2 can be expressed by the following expression (7).

[0077] [Expression 7]

[0078]

[0079] From the above-mentioned expressions (6) and (7), the following expression (8) is obtained. Note that in expression (8), m is an integer.

[0080] [Expression 8]

[0081] L+Δnd=λm...(8)

[0082] In the case where the optical path length (L+Δnd) between the substrates is an integral multiple of the wavelength of the incident light, the combined wave Φ2 is a combination of waves having respective wavefronts identical to each other. This makes it possible to prevent the occurrence of interference of wavefronts.

[0083] In the case where the phase modulation element 100 is a transmissive liquid crystal element, the setting section 12 (or the adjustment section 13) of the phase modulation device 1 can set the phase modulation amount of the phase modulation element 100 that allows the optical path length between the first substrate 101 and the second substrate 102 to be an integral multiple of the wavelength of the light from the light source 60 to the reference phase value θc. The above-mentioned offset adjustment of the phase modulation amount based on the reference phase value θc reduces the phase difference between the multiple reflected light beams. Therefore, it is possible to prevent the interference of the wavefront caused by the multiple reflected light beams, and it is possible to suppress the degradation of the image quality.

[0084] Figure 7 and Figure 8 1 is a diagram for describing an exemplary setting of a phase adjustment range performed by the phase modulation device according to the first embodiment. The setting section 12 may set a median value of a setting range of the phase modulation amount based on the optical path length of each pixel P. For example, the setting section 12 may set a median value of a setting range to reduce the amount of phase modulation by changing the phase amount θ to θ. k The remainder obtained by dividing by 2π and the reference phase value θc The difference between is squared to obtain the sum of values ​​S2 (see the following expression (9)). Phase quantity θ k Based on the optical path length of each pixel P.

[0085] [Expression 9]

[0086]

[0087] In this case, the setting unit 12 may set the median of the setting range of the phase modulation amount so that the sum S2 is minimized. This makes it possible to effectively suppress the interference of wavefronts caused by multiple reflected light beams even when there is a difference in the optical path length between the pixels P of the phase modulation element 100. Therefore, in the case where the optical path length of each pixel P is uneven, it is possible to prevent image quality from being deteriorated.

[0088] In addition, as in Figure 8 In the embodiment shown in , the setting section 12 can set the setting range so as to allow the difference between the median value and the upper limit value of the setting range of the phase modulation amount to be a phase difference greater than or equal to half a wavelength (a phase difference greater than or equal to π). Alternatively, the setting section 12 can set the setting range so as to allow the difference between the median value and the lower limit value of the setting range of the phase modulation amount to be a phase difference greater than or equal to half a wavelength. This makes it possible to prevent a large potential difference from being generated between the pixels of the phase modulation element 100, and to prevent obstruction in obtaining a desired phase modulation amount. It is possible to prevent image quality degradation caused by disclination.

[0089] [Work and Effect]

[0090] The phase modulation device (phase modulation device 1) according to the present embodiment includes: a phase modulation element (phase modulation element 100) including a plurality of pixels and configured to modulate the phase of light from a light source (light source 60); a generation section (generation section 11) configured to generate first data (phase distribution data) about the phase modulation amount of each pixel; and an adjustment section (adjustment section 13) configured to adjust the first data so that the phase modulation range includes a reference phase value (reference phase value θc) based on the wavelength of the light from the light source. The phase modulation element is configured to modulate the phase of the light from the light source based on the first data adjusted by the adjustment section.

[0091] In the phase modulation device 1 according to the present embodiment, the phase of the light from the light source 60 is modulated based on the phase distribution data D2 adjusted so that the phase modulation range includes the reference phase value θc based on the wavelength of the light from the light source 60. This makes it possible to suppress the occurrence of interference of the wavefront caused by the multi-reflected light beam. Therefore, it is possible to suppress the degradation of image quality.

[0092] <2. Second Embodiment>

[0093] Next, a description is given of a second embodiment of the present invention. Hereinafter, the same components as those in the foregoing embodiment are denoted by the same reference numerals, and description thereof is appropriately omitted.

[0094] Fig. 9 1 is a diagram showing an example of a schematic configuration of a phase modulation device according to a second embodiment of the present disclosure. In the present embodiment, the phase modulation device 1 further includes a measuring section 70 and a calculating section 80. The measuring section 70 is configured to measure light from the phase modulation element 100. The measuring section 70 includes, for example, a photodiode sensor, a CCD image sensor, a CMOS image sensor, etc.

[0095] The measuring section 70 is configured to perform photoelectric conversion on incident light to thereby generate a signal. The measuring section 70 may receive light that has been phase-modulated by the phase modulation element 100, and as a result of the measurement, generate and output a signal D11 as an electrical signal based on the amount of received light. For example, the measuring section 70 outputs the signal D11 corresponding to the intensity of the emitted light that has been phase-modulated by the phase modulation element 100 to the calculating section 80.

[0096] The calculation section 80 is configured to calculate the phase modulation amount based on the signal D11 received from the measurement section 70. For example, the calculation section 80 calculates (detects) the phase modulation amount θ1 of the phase modulation element 100 that allows the intensity of light from the phase modulation element 100 to be the highest based on the signal D11. The calculation section 80 generates a signal D12 representing the phase modulation amount θ1 thus calculated, and outputs the signal D12 to the setting section 12 of the signal processing unit 10. It should be noted that the measurement section 70 and the calculation section 80 may be integrated. Alternatively, the signal processing unit 10 may include the calculation section 80.

[0097] The setting section 12 is configured to change the phase setting range data regarding the setting range of the phase modulation amount based on the measurement result of the measuring section 70. The setting section 12 can adjust the median value, upper limit value, lower limit value, etc. of the setting range of the phase modulation amount based on the signal D12 received from the calculating section 80. For example, the setting section 12 sets the phase modulation amount θ1 indicated by the signal D12 to the median value of the setting range, thereby adjusting the phase setting range data. The setting section 12 outputs the phase setting range data thus adjusted to the adjusting section 13.

[0098] The adjustment unit 13 is configured to adjust the phase distribution data based on the measurement result of the measurement unit 70. Fig. 9In the example shown, the adjustment section 13 receives the phase setting range data changed by the setting section 12. The adjustment section 13 adjusts the phase distribution data D1 according to the phase setting range data, thereby generating the phase distribution data D2. It should be noted that the adjustment section 13 can change the phase distribution data D2 based on the phase setting range data. The driving section 50 supplies a voltage to each pixel P of the phase modulation element 100, thereby obtaining the phase distribution represented by the phase distribution data D2.

[0099] As described above, in the present embodiment, the phase modulation amount of each pixel P of the phase modulation element 100 can be adjusted based on the measurement result of the measurement section 70. This makes it possible to adjust the phase modulation range and suppress the interference of the wavefront caused by the multiple reflected light beams even when the characteristics of the phase modulation element 100 change over time. Therefore, the phase modulation amount can be optimized and the image quality can be improved.

[0100] [Work and Effect]

[0101] The phase modulation device (phase modulation device 1) according to the present embodiment includes a measuring section (measuring section 70) configured to measure light from a phase modulation element (phase modulation element 100). An adjusting section (adjusting section 13) is configured to adjust the first data (phase distribution data) based on the measurement result of the measuring section.

[0102] In the phase modulation device 1 according to the present embodiment, the phase distribution data is adjusted based on the measurement result of the measurement section 70, and the phase of the light from the light source 60 is modulated. This makes it possible to suppress the occurrence of interference of wavefronts caused by multiple reflected light beams and to suppress degradation of image quality.

[0103] Next, a modification of the present disclosure is described. Hereinafter, the same components as those in the foregoing embodiment are denoted by the same reference numerals, and description thereof is appropriately omitted.

[0104] <3. Modifications>

[0105] In the above-described embodiments, configuration examples of the phase modulation device have been described; however, the phase modulation device is not limited to these embodiments in construction. The phase modulation device 1 may include a light source different from the light source 60, and the light source may be used as a light source for measuring light that has been phase-modulated at the phase modulation element 100. It should be noted that the wavelength of the light of the measurement light source may also be determined in such a way that the light from the light source is largely reflected by the electrodes (the first electrode 20a and the second electrode 20b) of the phase modulation element 100. This makes it possible to accurately measure the intensity of the light from the phase modulation element 100. It should be noted that the measurement light source may have a wavelength outside the wavelength range of visible light.

[0106] The phase modulation device 1 may include an optical system that separates the optical path, and the optical system may measure the light from the phase modulation element 100. In addition, the measurement section 70 of the phase modulation device 1 may perform measurement using high-order diffracted light. In addition, the phase modulation device 1 may include a measurement device configured to measure the brightness distribution on the image plane of the phase modulation element 100 as the measurement section 70.

[0107] In the above embodiment, the configuration examples of the phase modulation element 100 have been described; however, these examples are only examples, and the phase modulation element 100 is not limited in configuration to the above examples. For example, the phase modulation element 100 may not include the anti-reflection film 40.

[0108] Although the present disclosure has been described with reference to the embodiments and the modified examples, the present technology is not limited to the above-described embodiments and the modified examples, and various modifications are possible. For example, although the above-described modified examples have been described as modified examples of the above-described embodiments, the respective configurations of the modified examples may be appropriately combined.

[0109] The phase modulation device provided by the embodiment of the present disclosure includes: a phase modulation element; a generating unit configured to generate first data about the phase modulation amount of each pixel; and an adjusting unit configured to adjust the first data so that the phase modulation range includes a reference phase value based on the wavelength of the light from the light source. The phase modulation element is configured to modulate the phase of the light from the light source based on the first data adjusted by the adjusting unit. This makes it possible to suppress the interference of wavefronts caused by multiple reflected light beams and to suppress the degradation of image quality.

[0110] It should be noted that the effects described here are merely illustrative and non-restrictive, and other effects may be provided. In addition, the present disclosure may have the following configurations. (1)

[0112] A phase modulation device, comprising:

[0113] a phase modulation element comprising a plurality of pixels and configured to modulate the phase of light from a light source;

[0114] a generating section configured to generate first data on a phase modulation amount of each of a plurality of pixels; and

[0115] an adjusting unit configured to adjust the first data so that the phase modulation range includes a reference phase value based on the wavelength of the light from the light source, wherein

[0116] The phase modulation element is configured to modulate the phase of the light from the light source based on the first data adjusted by the adjustment section. (2)

[0118] The phase modulation device according to (1), wherein the reference phase value is a phase modulation amount set so that the light beams multiply reflected in the phase modulation element have respective phases identical to each other. (3)

[0120] The phase modulation device according to (1) or (2), wherein the adjustment section is configured to adjust the first data so that a difference between a phase modulation amount of each of the plurality of pixels and a reference phase value is reduced. (4)

[0122] The phase modulation device according to any one of (1) to (3), wherein the adjustment section is configured to shift the phase modulation amount so that a sum of values ​​obtained by squaring a difference between the phase modulation amount of each of the plurality of pixels and the reference phase value decreases. (5)

[0124] The phase modulation device according to any one of (1) to (4), wherein the generation section is configured to generate the first data by performing light propagation calculation once. (6)

[0126] The phase modulation device according to any one of (1) to (4), wherein the generation section is configured to generate the first data by performing the light propagation calculation a plurality of times. (7)

[0128] The phase modulation device according to any one of (1) to (6), wherein:

[0129] The phase modulation element includes a first substrate, a second substrate opposite to the first substrate, and a liquid crystal layer disposed between the first substrate and the second substrate and including liquid crystal molecules, and

[0130] The phase modulation element is a reflective liquid crystal element. (8)

[0132] The phase modulation device according to (7), wherein the reference phase value is a phase modulation amount of the phase modulation element that allows an optical path length between the first substrate and the second substrate to become an integral multiple of a half wavelength of light from the light source. (9)

[0134] The phase modulation device according to (7) or (8), comprising:

[0135] A setting unit is configured to set a setting range of a phase modulation amount of a phase modulation element, wherein

[0136] The setting section is configured to set a median value of the setting range based on an optical path length of each of the plurality of pixels. (10)

[0138] The phase modulation device according to any one of (7) to (9), comprising:

[0139] A setting unit is configured to set a setting range of a phase modulation amount of a phase modulation element, wherein

[0140] The setting section is configured to set the setting range to allow a difference between a median value and an upper limit value of the setting range and a difference between the median value and a lower limit value of the setting range to be a phase difference greater than or equal to a half wavelength. (11)

[0142] The phase modulation device according to any one of (1) to (6), wherein:

[0143] The phase modulation element includes a first substrate, a second substrate opposite to the first substrate, and a liquid crystal layer disposed between the first substrate and the second substrate and including liquid crystal molecules, and

[0144] The phase modulation element is a transmissive liquid crystal element. (12)

[0146] The phase modulation device according to (11), wherein the reference phase value is a phase modulation amount of the phase modulation element that makes the optical path length between the first substrate and the second substrate an integral multiple of the wavelength of the light from the light source. (13)

[0148] The phase modulation device according to (11) or (12), comprising:

[0149] A setting unit is configured to set a setting range of a phase modulation amount of a phase modulation element, wherein

[0150] The setting section is configured to set a median value of the setting range based on an optical path length of each element in the plurality of pixels. (14)

[0152] The phase modulation device according to any one of (11) to (13), comprising:

[0153] A setting unit is configured to set a setting range of a phase modulation amount of a phase modulation element, wherein

[0154] The setting section is configured to set the range to allow a difference between a median value and an upper limit value of the set range and a difference between the median value and a lower limit value of the set range to be a phase difference greater than or equal to a half wavelength. (15)

[0156] The phase modulation device according to any one of (1) to (14), comprising:

[0157] a measuring unit configured to measure light from the phase modulation element, wherein

[0158] The adjustment section is configured to adjust the first data based on a measurement result of the measurement section. (16)

[0160] The phase modulation device according to any one of (1) to (15), comprising:

[0161] a measuring section configured to measure light from the phase modulation element; and

[0162] A setting unit is configured to set a setting range of a phase modulation amount of a phase modulation element, wherein:

[0163] The setting section is configured to set the range based on a measurement result by the measuring section. (17)

[0165] The phase modulation device according to any one of (1) to (16), comprising:

[0166] a measuring section configured to measure light from the phase modulation element; and

[0167] A setting unit is configured to set a setting range of a phase modulation amount of a phase modulation element, wherein:

[0168] The setting section is configured to set the phase modulation amount of the phase modulation device that allows the intensity of light from the phase modulation element to be the highest to a median value of the setting range.

[0169] This application claims the benefit of Japanese Patent Application No. 2022-082327 filed with the Japan Patent Office on May 19, 2022, the entire contents of which are hereby incorporated by reference.

[0170] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

Claims

1. A phase modulation device, comprising: a phase modulation element comprising a plurality of pixels and configured to modulate the phase of light from a light source; a generating section configured to generate first data on a phase modulation amount of each pixel of the plurality of pixels; as well as an adjusting unit configured to adjust the first data so that the phase modulation range includes a reference phase value based on the wavelength of the light from the light source, wherein The phase modulation element is configured to modulate the phase of light from the light source based on the first data adjusted by the adjustment section.

2. The phase modulation device according to claim 1, wherein: The reference phase value includes a phase modulation amount which is set so that light beams multiply reflected in the phase modulation element have respective phases which are the same as each other.

3. The phase modulation device according to claim 1, wherein: The adjustment section is configured to adjust the first data so that a difference between a phase modulation amount of each of the plurality of pixels and the reference phase value is reduced.

4. The phase modulation device according to claim 1, wherein: The adjustment section is configured to shift the phase modulation amount so that a sum of values ​​obtained by squaring a difference between the phase modulation amount of each of the plurality of pixels and the reference phase value decreases.

5. The phase modulation device according to claim 1, wherein: The generating section is configured to generate the first data by performing a light propagation calculation once.

6. The phase modulation device according to claim 1, wherein: The generating section is configured to generate the first data by performing light propagation calculation a plurality of times.

7. The phase modulation device according to claim 1, wherein: The phase modulation element includes a first substrate, a second substrate opposite to the first substrate, and a liquid crystal layer disposed between the first substrate and the second substrate and including liquid crystal molecules, and The phase modulation element includes a reflective liquid crystal element.

8. The phase modulation device according to claim 7, wherein: The reference phase value includes a phase modulation amount of the phase modulation element that allows an optical path length between the first substrate and the second substrate to become an integral multiple of a half wavelength of light from the light source.

9. The phase modulation device according to claim 8, comprising: A setting unit is configured to set a setting range of the phase modulation amount of the phase modulation element, wherein The setting section is configured to set a median value of the setting range based on the optical path length of each of the plurality of pixels.

10. The phase modulation device according to claim 8, comprising: A setting unit is configured to set a setting range of the phase modulation amount of the phase modulation element, wherein The setting section is configured to set the setting range to allow a difference between a median value and an upper limit value of the setting range and a difference between the median value and a lower limit value of the setting range to be a phase difference greater than or equal to a half wavelength.

11. The phase modulation device according to claim 1, wherein: The phase modulation element includes a first substrate, a second substrate opposite to the first substrate, and a liquid crystal layer disposed between the first substrate and the second substrate and including liquid crystal molecules, and The phase modulation element includes a transmissive liquid crystal element.

12. The phase modulation device according to claim 11, wherein: The reference phase value includes a phase modulation amount of the phase modulation element that allows an optical path length between the first substrate and the second substrate to become an integral multiple of a wavelength of light from the light source.

13. The phase modulation device according to claim 12, comprising: A setting unit is configured to set a setting range of the phase modulation amount of the phase modulation element, wherein The setting section is configured to set a median value of the setting range based on the optical path length of each of the plurality of pixels.

14. The phase modulation device according to claim 12, comprising: A setting unit is configured to set a setting range of the phase modulation amount of the phase modulation element, wherein The setting section is configured to set the setting range to allow a difference between a median value and an upper limit value of the setting range and a difference between the median value and a lower limit value of the setting range to be a phase difference greater than or equal to a half wavelength.

15. The phase modulation device according to claim 1, comprising: A measuring unit is configured to measure light from the phase modulation element, wherein: The adjustment section is configured to adjust the first data based on a measurement result of the measurement section.

16. The phase modulation device according to claim 1, comprising: a measuring unit configured to measure light from the phase modulation element; as well as A setting unit is configured to set a setting range of the phase modulation amount of the phase modulation element, wherein: The setting section is configured to set the setting range based on a measurement result by the measuring section.

17. The phase modulation device according to claim 1, comprising: a measuring unit configured to measure light from the phase modulation element; as well as A setting unit is configured to set a setting range of the phase modulation amount of the phase modulation element, wherein: The setting section is configured to set a phase modulation amount of the phase modulation element that allows the intensity of light from the phase modulation element to be the highest to a median value of the setting range.

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