An imaging optical system and an imaging method

Abstract

The application discloses an imaging optical system and an imaging method, the system comprising a controller and sequentially arranged front mirror group, spatially tunable component, rear mirror group and imaging detector; the spatially tunable component is located on a primary image plane and comprises sequentially arranged first polarizer, liquid crystal spatial light modulator and second polarizer; the first polarizer is used for polarizing natural light emitted by a target object to obtain polarized light; the liquid crystal spatial light modulator is used for phase modulating the polarized light of a target coordinate region to obtain phase modulated light; the second polarizer is used for detecting the phase modulated light to obtain amplitude modulated light; and the imaging detector is used for receiving a target image corresponding to the amplitude modulated light. The system firstly performs phase modulation on incident light through the spatial light modulator, and then realizes amplitude modulation through the second polarizer, so that the dynamic range of the system is greatly improved; and the system can also realize one-time modulation of light intensity at different spatial positions of a light field, so that the modulation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to an imaging optical system and an imaging method. Background Art

[0002] Traditional optoelectronic systems achieve wide dynamic range imaging in two ways: The first is by using an imaging detector with a wide dynamic range. The second is through HDR (High Dynamic Range Imaging) technology. For example, this involves taking multiple exposures of the same scene, controlling the exposure time and gain of the imaging detector for each exposure, and then performing grayscale stitching on these images to simultaneously image both bright and dark objects in the scene. For example, when shooting a portrait against sunlight, both the sun and the person can be captured brightly.

[0003] During research into related technologies, the inventors discovered that the first method described above places high demands on the dynamic range of the imaging detector, and the upper limit of the dynamic range is not high. The second method, which achieves large dynamic range imaging through algorithmic techniques, requires multiple exposures, which reduces system timeliness. Furthermore, the upper limit of the dynamic range is constrained by the integration time and electronic gain of the imaging detector. Summary of the Invention

[0004] The present invention aims to at least solve the technical problems existing in the prior art. To this end, in a first aspect, the present invention provides an imaging optical system, comprising a controller and a front mirror group, a spatially tunable component, a rear mirror group, and an imaging detector arranged in sequence; the controller is electrically connected to the spatially tunable component and the imaging detector, and the optical axes of the front mirror group, the spatially tunable component, the rear mirror group, and the imaging detector respectively coincide with the main optical axis of the system;

[0005] The front lens group is composed of at least one group of lenses, and is used to image the target object on a primary image plane;

[0006] The spatially tunable component is located on the primary image plane, and includes a first polarizer, a liquid crystal spatial light modulator, and a second polarizer placed in sequence; the first polarizer is used to polarize the natural light emitted by the target object to obtain polarized light; the liquid crystal spatial light modulator is used to phase-modulate the polarized light in the target coordinate area after receiving the target modulation signal from the controller to obtain phase-modulated light; the second polarizer is used to analyze the phase-modulated light to obtain amplitude-modulated light;

[0007] The rear mirror group is composed of at least one group of lenses, and is used to image the amplitude modulated light onto a final image plane;

[0008] The imaging detector is located on the final image plane and is used to receive the target image corresponding to the amplitude modulated light.

[0009] Optionally, the liquid crystal spatial light modulator is a reflective liquid crystal spatial light modulator or a transmissive liquid crystal spatial light modulator.

[0010] Optionally, the front mirror group includes at least one of a first reflective mirror and a first transmissive mirror, and the rear mirror group includes at least one of a second reflective mirror and a second transmissive mirror.

[0011] Optionally, when the liquid crystal spatial light modulator is a reflective liquid crystal spatial light modulator, the main optical axis of the system is a broken line, and the second polarizer, the rear mirror group, and the imaging detector are arranged on the reflected light path of the reflective liquid crystal spatial light modulator;

[0012] When the liquid crystal spatial light modulator is a transmissive liquid crystal spatial light modulator, the main optical axis of the system is a straight line, and the front mirror group, the first polarizer, the transmissive liquid crystal spatial light modulator, the second polarizer, the rear mirror group and the imaging detector are arranged on a straight line.

[0013] A second aspect of the present invention provides an imaging method, which is applied to the system described in the first aspect, and includes:

[0014] When the liquid crystal spatial light modulator is in a fully transparent state, the controller acquires an initial image received by the imaging detector;

[0015] The controller divides the initial image into a plurality of grid areas of equal area;

[0016] The controller obtains the grayscale value of each pixel in each of the grid areas, and determines a target grid area requiring grayscale modulation from the plurality of grid areas based on the grayscale value;

[0017] The controller determines, based on a spatial mapping relationship between the photosensitive surface of the imaging detector and the liquid crystal spatial light modulator, that the target grid area corresponds to a target coordinate area on the liquid crystal spatial light modulator;

[0018] The controller generates a target modulation signal according to the grayscale value of the target coordinate area;

[0019] The liquid crystal spatial light modulator adjusts the phase of the polarized light passing through the target coordinate area according to the target modulation signal to obtain phase modulated light; the polarized light is natural light passing through the first polarizer;

[0020] After the phase modulated light is amplitude modulated by the analyzer of the second polarizer, the rear mirror group images the amplitude modulated light onto the imaging detector to obtain a target image; the grayscale values ​​of the pixels in the target network area of ​​the target image are within a preset grayscale range.

[0021] Optionally, the determining a target grid area requiring grayscale modulation from the multiple grid areas based on the grayscale value includes:

[0022] For each of the grid areas in the initial image, counting a first number of first pixel points whose grayscale values ​​are less than or equal to a preset first grayscale threshold;

[0023] If there is a first grid area where the first number is greater than a preset target number, sending a parameter adjustment instruction to the imaging detector, the parameter adjustment instruction including a target parameter and a target value of the target parameter; the target parameter being an initial parameter related to a response amplitude of the imaging detector;

[0024] The imaging detector adjusts the target parameter to the target value according to the parameter adjustment signal, so that the imaging detector displays a first image; the first image is an image in each grid area where the first number is smaller than the target number;

[0025] For each of the grid areas in the first image, counting a second number of pixels having a grayscale value greater than a preset second grayscale threshold;

[0026] The second grid areas whose second number is greater than the target number are determined as target grid areas.

[0027] Optionally, after counting the first number of first pixel points whose grayscale values ​​are less than or equal to a preset first grayscale threshold, the method further includes:

[0028] If there is no first grid area whose first number is greater than the preset target number, then for each of the grid areas in the initial image, counting a second number of second pixel points whose grayscale values ​​are greater than a preset second grayscale threshold;

[0029] The second grid areas whose second number is greater than the target number are determined as target grid areas.

[0030] Optionally, the target modulation signal includes a target rotation angle of liquid crystal molecules in the target coordinate region, and the liquid crystal spatial light modulator performs phase adjustment on polarized light in the target coordinate region according to the target modulation signal, including:

[0031] The liquid crystal spatial light modulator controls the liquid crystal molecules in the target coordinate area to rotate according to the target rotation angle according to the target modulation signal, so that the phase of the polarized light passing through the target coordinate area is adjusted.

[0032] Optionally, the preset grayscale range is between the first grayscale threshold and the second grayscale threshold.

[0033] Optionally, before the controller acquires the initial image received by the imaging detector, the method further includes:

[0034] After the system is powered on, the liquid crystal spatial light modulator sets the rotation angles of all liquid crystal molecules to the initial angles, so that the spatial light modulator is in a fully transparent state; the fully transparent state is a state with the highest transmittance of natural polarized light;

[0035] The rear mirror assembly images the target object located in front of the front mirror assembly onto the imaging detector;

[0036] The imaging detector receives an initial image corresponding to the target object.

[0037] The embodiments of the present invention have the following beneficial effects:

[0038] An imaging optical system provided by an embodiment of the present invention includes a controller and a front lens group, a spatially tunable component, a rear lens group, and an imaging detector, which are arranged in sequence. The controller is electrically connected to the spatially tunable component and the imaging detector, and the optical axes of the front lens group, the spatially tunable component, the rear lens group, and the imaging detector respectively coincide with the main optical axis of the system. The front lens group is composed of at least one group of lenses and is used to image a target object on a primary image plane. The spatially tunable component is located on the primary image plane, and the spatially tunable component includes a first polarizer, a liquid crystal spatial light modulator, and a second polarizer, which are arranged in sequence. The first polarizer is used to polarize natural light emitted by the target object to obtain polarized light. The liquid crystal spatial light modulator is used to phase modulate the polarized light in a target coordinate region after receiving a target modulation signal from the controller to obtain phase-modulated light. The second polarizer is used to analyze the phase-modulated light to obtain amplitude-modulated light. The rear lens group is composed of at least one group of lenses and is used to image the amplitude-modulated light onto a final image plane. The imaging detector is located on the final image plane and is used to receive a target image corresponding to the amplitude-modulated light. The system can phase modulate the incident light through the cooperation of the first polarizer and the spatial light modulator, and ultimately achieve amplitude modulation through the second polarizer, greatly improving the dynamic range of the system; moreover, the system can phase modulate the polarized light in the target coordinate area, realizing one-time modulation of the light intensity at different spatial positions in the light field, significantly improving the modulation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic diagram of an imaging optical system provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of an optical path of an imaging optical system including a reflective liquid crystal spatial light modulator provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of an optical path of an imaging optical system including a transmissive liquid crystal spatial light modulator provided by an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of a practical scenario provided by an embodiment of the present invention;

[0043] Figure 5 A flowchart of the steps of an imaging method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0045] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "multiple" means two or more. In addition, the use of "based on" or "according to" means openness and inclusiveness, because the process, steps, calculations or other actions "based on" or "according to" one or more of the conditions or values ​​may be based on additional conditions or values ​​beyond the stated in practice.

[0046] Figure 1 Schematic diagram of an imaging optical system provided by an embodiment of the present invention.

[0047] like Figure 1 As shown, the system includes a controller and a front mirror group, a spatially tunable component, a rear mirror group, and an imaging detector arranged in sequence. The controller is electrically connected to the spatially tunable component and can send electrical signals to the spatially tunable component.

[0048] The optical axes of the front mirror group, the spatially tunable component, the rear mirror group and the imaging detector respectively coincide with the main optical axis of the system.

[0049] The front lens group is composed of at least one set of lenses, which is used to image the target object on the primary image plane.

[0050] The spatial tunable component is located on the primary image plane and receives the image of the target object from the front lens group. The spatial tunable component includes a first polarizer, a liquid crystal spatial light modulator and a second polarizer placed in sequence. The first polarizer is placed in front of the liquid crystal spatial light modulator and serves as a polarizer to convert the natural light emitted by the target object into polarized light. The light rays in the natural light propagate in various directions, while the polarizer selectively allows light rays propagating in only one vibration direction to pass through, removing light wave information in other directions.

[0051] The liquid crystal spatial light modulator can receive electrical signals from the controller. The liquid crystal spatial light modulator includes but is not limited to LC-SLM (Liquid Crystal-Spatial Light Modulator), or ordinary LCD (Liquid Crystal Display), etc. The liquid crystal spatial light modulator is composed of two parallel glass substrates combined with polarized materials, with a liquid crystal layer in between, and the rotation direction of the liquid crystal molecules in the liquid crystal layer is controlled by voltage to realize imaging.

[0052] The liquid crystal spatial light modulator receives polarized light through the first polarizer, and after receiving the target modulation signal from the controller, rotates the liquid crystal molecules in the corresponding area according to the angle specified in the target modulation signal, changes the polarization direction of the polarized light, which is equivalent to phase modulation of the polarized light, and makes the polarized light become phase modulation light. The phase modulation light passes through the second polarizer, which acts as an analyzer and only allows light vibrating in a specific direction to pass through, and cannot allow light vibrating perpendicular to the direction to pass through. The second polarizer finally outputs the projection light of the phase modulation light on the second polarizer plane, changes the intensity of the phase modulation light, thereby realizing amplitude modulation of the light on the primary image plane, obtaining amplitude modulation light, and changing the brightness of the light.

[0053] The rear lens group is composed of at least one set of lenses, which is used to image the amplitude modulation light onto the final image plane.

[0054] The imaging detector is located on the final image plane and is a kind of photoelectric sensor, which is a device for observing and recording particles based on imaging. The imaging detector receives the target image corresponding to the amplitude modulation light.

[0055] As an optional embodiment, the liquid crystal spatial light modulator is a reflective liquid crystal spatial light modulator or a transmissive liquid crystal spatial light modulator.

[0056] The liquid crystal spatial light modulator consists of cover glass, front transparent electrode, liquid crystal layer, pixel layer, integrated circuit backplane and other structures.

[0057] The pixel layer is located at the bottom of the liquid crystal layer. The pixel layer of the reflective liquid crystal spatial light modulator is a reflector pixel, which is a reflective layer coated with aluminum or a dielectric film and has a very high reflection efficiency.

[0058] The pixel layer of a transmissive LC spatial light modulator (SLM) is a transmissive mirror pixel, allowing light to pass through. Reflective LC SLMs achieve modulation by reflecting light, offering high light utilization and deep modulation depth, but are relatively expensive and are suitable for applications requiring high light intensity, such as laser processing. Transmissive LC SLMs modulate light by transmitting it through, offering advantages such as a simple structure, low cost, and ease of integration, but with relatively low light utilization. They are commonly used in fields such as optical communications and optical displays.

[0059] As an optional embodiment, when the liquid crystal spatial light modulator is a reflective liquid crystal spatial light modulator, the main optical axis of the system is a broken line, and the second polarizer, the rear mirror group, and the imaging detector are arranged on the optical path of the reflected light of the reflective liquid crystal spatial light modulator;

[0060] When the liquid crystal spatial light modulator is a transmissive liquid crystal spatial light modulator, the main optical axis of the system is a straight line, and the front mirror group, the first polarizer, the transmissive liquid crystal spatial light modulator, the second polarizer, the rear mirror group and the imaging detector are arranged on a straight line.

[0061] Figure 2 A schematic diagram of the optical path of an imaging optical system including a reflective liquid crystal spatial light modulator provided by an embodiment of the present invention.

[0062] like Figure 2 As shown, in an optical system comprising a reflective liquid crystal spatial light modulator, the system's principal optical axis becomes a broken line after passing through the reflective liquid crystal spatial light modulator. A second polarizer, a rear mirror assembly, and an imaging detector are positioned along the reflected light path of the reflective liquid crystal spatial light modulator. The reflective liquid crystal spatial light modulator phase-modulates the polarized light passing through the first polarizer and then reflects it onto the second polarizer, which analyzes the light to produce amplitude-modulated light.

[0063] Figure 3 A schematic diagram of the optical path of an imaging optical system including a transmissive liquid crystal spatial light modulator provided by an embodiment of the present invention.

[0064] like Figure 3As shown, in an optical system including a transmissive liquid crystal spatial light modulator (LCSLM), the system's principal optical axis is a straight line, along which the front lens group, first polarizer, LCSLM, second polarizer, rear lens group, and imaging detector are arranged. The LCSLM phase-modulates polarized light passing through the first polarizer and transmits it to the second polarizer, which analyzes the light to produce amplitude-modulated light.

[0065] As an optional embodiment, the front mirror group includes at least one of a first reflective mirror and a first transmissive mirror, and the rear mirror group includes at least one of a second reflective mirror and a second transmissive mirror.

[0066] Specifically, the front lens group and the rear lens group can be designed as a transmissive structure, a reflective structure, or a hybrid transmissive-reflective structure. That is, the front lens group can be solely the first reflector or the first transmissive mirror, or can be composed of the first transmissive mirror and the first reflector together. The rear lens group can be solely the second reflector or the second transmissive mirror, or can be composed of the second transmissive mirror and the second reflector together.

[0067] The front and rear lens groups are preferably a hybrid transflective structure. The hybrid structure of the front lens group allows the target object to be imaged as perfectly as possible on the primary image plane, while any residual aberrations can be compensated by the rear lens group. Therefore, the rear lens group is also preferably a hybrid structure, both to compensate for the residual aberrations of the front lens group and to relay the image from the primary image plane to the final image plane.

[0068] Figure 4 A schematic diagram of a practical scenario provided by an embodiment of the present invention.

[0069] like Figure 4 As shown, when the imaging optical system in this scheme images a target object, if a strong light source, such as the sun, appears in the scene, the light emitted by the sun is amplitude modulated by the spatially tunable component, so that the amplitude intensity of this part of the light is effectively modulated, and finally this part of the light is received by the detector without saturation.

[0070] In summary, the imaging optical system provided by the embodiment of the present invention includes a controller and a front mirror group, a spatially tunable component, a rear mirror group and an imaging detector arranged in sequence; the controller is electrically connected to the spatially tunable component and the imaging detector, and the optical axes of the front mirror group, the spatially tunable component, the rear mirror group and the imaging detector respectively coincide with the main optical axis of the system; the front mirror group is composed of at least one group of lenses and is used to image a target object on a primary image plane; the spatially tunable component is located on the primary image plane, and the spatially tunable component includes a first polarizer, a liquid crystal spatial light modulator, and a second polarizer arranged in sequence; the first polarizer is used to polarize natural light emitted by the target object to obtain polarized light; the liquid crystal spatial light modulator is used to phase modulate the polarized light in the target coordinate area after receiving a target modulation signal from the controller to obtain phase-modulated light; the second polarizer is used to analyze the phase-modulated light to obtain amplitude-modulated light; the rear mirror group is composed of at least one group of lenses and is used to image the amplitude-modulated light onto a final image plane; and the imaging detector is located on the final image plane to receive a target image corresponding to the amplitude-modulated light. The system can phase modulate the incident light through the cooperation of the first polarizer and the spatial light modulator, and ultimately achieve amplitude modulation through the second polarizer, greatly improving the dynamic range of the system; moreover, the system can phase modulate the polarized light in the target coordinate area, realizing one-time modulation of the light intensity at different spatial positions in the light field, significantly improving the modulation efficiency.

[0071] Figure 5 A flowchart of the steps of an imaging method provided by an embodiment of the present invention.

[0072] This method is applied to Figure 1-Figure 3 Any system in Figure 5 As shown, the method includes the following steps:

[0073] Step 101: When the liquid crystal spatial light modulator is in a fully transparent state, the controller obtains an initial image received by the imaging detector.

[0074] In an embodiment of the present invention, a target object is placed in front of the front lens assembly of the imaging optical system, and the liquid crystal spatial light modulator is set to a fully transparent state. A controller can then capture an image displayed on the photosensitive surface of the imaging detector. This image serves as the initial image of the target object, and the controller subsequently detects whether this initial image contains excessively bright or dark areas.

[0075] As an optional embodiment, before the controller acquires the initial image received by the imaging detector, the method further includes:

[0076] Step 201: After the system is powered on, the liquid crystal spatial light modulator sets the rotation angles of all liquid crystal molecules to initial angles, so that the spatial light modulator is in a fully transparent state; the fully transparent state is a state with the highest transmittance of naturally polarized light;

[0077] Step 202: The rear lens assembly images the target object located in front of the front lens assembly onto the imaging detector;

[0078] Step 203: The imaging detector receives an initial image corresponding to the target object.

[0079] In steps 201 to 203, after the system is powered on, the liquid crystal spatial light modulator does not perform modulation. At this time, the liquid crystal spatial light modulator is in a fully transparent state, that is, the incident light of the target object passing through the first polarizer can pass through the liquid crystal spatial light modulator with maximum efficiency. The rear mirror group directly forms an image of the target object, and the imaging detector displays the initial image corresponding to the target object.

[0080] Step 102: The controller divides the initial image into a plurality of grid regions of equal area.

[0081] To detect whether the initial image contains overly bright or dark areas, the controller first divides the initial image into multiple grid areas of equal size. The size of the grid area can be set as required.

[0082] Step 103 : The controller obtains the grayscale value of each pixel in each of the grid areas, and determines a target grid area requiring grayscale modulation from the multiple grid areas based on the grayscale value.

[0083] The controller obtains the grayscale value of each pixel in each grid area, determines the number of bright and dark points in the grid area based on the grayscale value, and determines whether the grid area needs grayscale modulation based on the number of bright and dark points. The controller determines the grid area that needs grayscale modulation as the target grid area.

[0084] As an optional embodiment, determining a target grid area requiring grayscale modulation from the multiple grid areas based on the grayscale value includes:

[0085] Step 1031: For each grid area in the initial image, count a first number of first pixel points whose grayscale value is less than or equal to a preset first grayscale threshold.

[0086] Step 1032: If there is a first grid area where the first number is greater than a preset target number, a parameter adjustment instruction is sent to the imaging detector, where the parameter adjustment instruction is used to adjust a target parameter of the imaging detector; the target parameter is a parameter related to the response amplitude of the imaging detector;

[0087] Step 1033: The imaging detector adjusts the target parameter according to the parameter adjustment signal, so that the imaging detector displays a first image; the first image is an image in which the first number is greater than the target number;

[0088] Step 1034: For each grid area in the first image, count a second number of pixels having a grayscale value greater than a preset second grayscale threshold;

[0089] Step 1035: Determine the second grid areas whose second number is greater than the target number as target grid areas.

[0090] In steps 1031 to 1035, the first grayscale threshold and the second grayscale threshold can be preset as needed, with the first grayscale threshold being a value close to 0 and the second grayscale threshold being a value close to 255. For example, the first grayscale threshold can be set to 5 and the second grayscale threshold can be set to 230.

[0091] For each grid area in the initial image, the number of pixels having a grayscale value less than or equal to a first grayscale threshold is counted to obtain a first number, and it is determined whether the first number is greater than a preset target number.

[0092] Specifically, the target number is set according to the total number of pixels included in a grid area, and the value of the target number is close to the total number of pixels. For example, the target number can be set to 80% of the total number of pixels.

[0093] If the first number is greater than the preset target number, the grid area is determined as the first grid area.

[0094] Pixels whose grayscale values ​​are less than or equal to the first grayscale threshold are dark spots with low grayscale values. The number of dark spots in the first grid area is greater than the target number, indicating that the first grid area is darker as a whole and underexposed, which will bring a bad visual experience and requires grayscale modulation.

[0095] Therefore, after determining that a first number of first grid areas exists that is greater than a preset target number, the controller sends a parameter adjustment instruction to the imaging detector. The parameter adjustment instruction includes a target parameter and a target value for the target parameter. The target parameter is an initial parameter related to the response amplitude of the imaging detector, such as integration time, gain, and other parameters.

[0096] A detector's integration time refers to the length of time it integrates the light signal. In photoelectric detection, this integration time is used to collect the energy of the light signal and convert it into an electrical signal. The length of this integration time directly affects the detector's sensitivity to light signals and its signal-to-noise ratio. Generally speaking, a longer integration time results in more light signal energy collected by the detector, a higher signal-to-noise ratio, and a slower detector response.

[0097] Detector gain is the ratio of input charge to output charge and is often used to reflect the detector's sensitivity and resolution. A greater gain results in a more responsive detector to the input signal, enabling detection of weaker signals and improving energy resolution.

[0098] The imaging detector adjusts the target parameter to a target value based on the parameter adjustment signal, thereby increasing the grayscale value of pixels of the initial image displayed on the image plane of the imaging detector, thereby obtaining a first image. In the grid area of ​​the first image, a first number of first pixels having grayscale values ​​less than or equal to the first grayscale threshold is less than the target number.

[0099] Next, for each grid area in the first image, a second number of pixels having a grayscale value greater than a second grayscale threshold is counted to determine whether the second number is greater than a target number. The second grid area having the second number greater than the target number is determined as a target grid area.

[0100] Pixels with grayscale values ​​greater than the second grayscale threshold are considered bright spots with excessively high grayscale values. If the number of bright spots in the second grid area exceeds the target number, this indicates that the second grid area is brighter overall and overexposed. This grid area also creates a poor visual experience and is a target grid area that requires grayscale modulation.

[0101] It is understood that the first grid area may or may not exist in the initial image. After executing step 1031, if it is found that the first number is less than the preset target number, the following step 1032 is not executed, and step 1036 is executed instead. That is:

[0102] As an optional embodiment, after step 1031, the method further includes:

[0103] Step 1031: If there are no first grid areas whose first number is greater than the preset target number, then for each of the grid areas in the initial image, count a second number of second pixels whose grayscale values ​​are greater than a preset second grayscale threshold;

[0104] Step 1032: Determine the second grid areas whose second number is greater than the target number as target grid areas.

[0105] In steps 1031 and 1032, if there are no first grid areas whose first number is greater than the target number, then there are no dark areas with low grayscale values ​​in the initial image, and no adjustment is required for the dark areas. The second number of second pixels in the initial image whose grayscale values ​​are greater than the second grayscale threshold is then directly counted to determine whether there are bright areas with excessively high grayscale values.

[0106] When the second number of second grid areas that is greater than the target number exists in the initial image, the second grid areas are determined as target grid areas that require grayscale value adjustment.

[0107] It is understood that the initial image may or may not contain the second grid area. If the second grid area does not exist, it indicates that there is no bright spot area with excessively high grayscale values ​​in the initial image, indicating that there is no grid area in the initial image that requires grayscale modulation, and the process ends after step 1031.

[0108] Step 104 : The controller determines, based on the spatial mapping relationship between the imaging detector photosensitive surface and the liquid crystal spatial light modulator, that the target grid area corresponds to a target coordinate area on the liquid crystal spatial light modulator.

[0109] Record the pixel coordinates (x i_1 ~x i_m ,y i_1 ~y i_n ), according to the spatial mapping relationship between the detector photosensitive surface and the liquid crystal spatial light modulator, the target grid area corresponding to the target coordinate area (x t_1 ~x t_m ,y t_1 ~y t_n ) 。

[0110] Step 105: The controller generates a target modulation signal according to the grayscale value of the target coordinate area.

[0111] The controller generates a corresponding target modulation signal according to a magnitude relationship between the grayscale value of the target coordinate area and the second grayscale threshold.

[0112] As an optional embodiment, the target modulation signal includes a target rotation angle of the liquid crystal molecules in the target coordinate area.

[0113] Specifically, for the pixels in the target grid area, the grayscale value of the pixels needs to be reduced to a preset grayscale range. The controller can determine the extent to which the grayscale value needs to be reduced based on the current grayscale value. For example, if the preset grayscale range is (5, 230], and the highest grayscale value in the target grid area is 255, the controller can determine that the grayscale value needs to be reduced by 25, that is, the grayscale value of each pixel in the first grid area is reduced by 25. In this way, it can be ensured that the grayscale value of each pixel in the first grid area is 230 or below.

[0114] The controller determines the target rotation angle of the liquid crystal molecules in the target coordinate region according to the magnitude of the grayscale value required to be reduced, thereby generating a target modulation signal. The target modulation signal may include target coordinate region information and target rotation angle information.

[0115] Step 106 : The liquid crystal spatial light modulator performs phase adjustment on the polarized light passing through the target coordinate area according to the target modulation signal to obtain phase modulated light; the polarized light is natural light passing through the first polarizer.

[0116] The liquid crystal spatial light modulator receives the polarized light passing through the first polarizer, and after receiving the target modulation signal from the controller, it rotates the liquid crystal molecules in the corresponding area according to the angle specified in the target modulation signal, so that the polarization direction of the polarized light changes, which is equivalent to phase adjustment of the polarized light, turning the polarized light into phase modulated light.

[0117] As an optional embodiment, the target modulation signal includes a target rotation angle of the liquid crystal molecules in the target coordinate region, and the liquid crystal spatial light modulator adjusts the phase of the polarized light in the target coordinate region according to the target modulation signal, including:

[0118] The liquid crystal spatial light modulator controls the liquid crystal molecules in the target coordinate area to rotate according to the target rotation angle according to the target modulation signal, so that the phase of the polarized light passing through the target coordinate area is adjusted.

[0119] The liquid crystal spatial light modulator controls the liquid crystal molecules in the target coordinate area to rotate at a target angle, thereby causing the polarization degree of the polarized light in the target coordinate area to change accordingly, thereby obtaining a corresponding phase adjustment amplitude.

[0120] Step 107: After the phase modulated light is amplitude modulated by the analyzer of the second polarizer, the rear mirror group images the amplitude modulated light onto the imaging detector to obtain a target image; the grayscale values ​​of the pixels in the target network area of ​​the target image are within a preset grayscale range.

[0121] The phase-modulated light passes through the second polarizer, which acts as an analyzer, allowing only light vibrating in a specific direction to pass through, while blocking light vibrating perpendicular to that direction. The second polarizer ultimately outputs the phase-modulated light as a projection along the second polarizer's polarization direction, changing its intensity. This modulates the amplitude of the light on the primary image plane, producing amplitude-modulated light and altering its brightness.

[0122] The rear mirror assembly images the amplitude modulated light onto the final image plane. The imaging detector is located on the final image plane and is used to receive the target image corresponding to the amplitude modulated light.

[0123] The grayscale values ​​of the pixels in the target grid area of ​​the initial image are within the preset grayscale range after modulation, so that the grayscale values ​​of the pixels in the target image are all within the preset grayscale range.

[0124] As an optional embodiment, the preset grayscale range is between the first grayscale threshold and the second grayscale threshold.

[0125] Exemplarily, the preset grayscale range is (5, 230). In this way, the grayscale values ​​of the pixels in each grid area of ​​the target image can be between the first grayscale threshold and the second grayscale threshold, so that the pixels are neither too bright nor too dark, thereby improving the visual effect of the target image.

[0126] In summary, the imaging method provided by the embodiments of the present invention comprises the following steps: when the liquid crystal spatial light modulator is in a fully transparent state, the controller obtains an initial image received by the imaging detector; the controller divides the initial image into multiple grid areas of equal area; the controller obtains the grayscale value of each pixel in each grid area, and determines a target grid area to be grayscale modulated from the multiple grid areas based on the grayscale value; the controller determines, based on a spatial mapping relationship between the photosensitive surface of the imaging detector and the liquid crystal spatial light modulator, that the target grid area corresponds to a target coordinate area on the liquid crystal spatial light modulator; the controller generates a target modulation signal based on the grayscale value of the target coordinate area; the liquid crystal spatial light modulator phase modulates polarized light passing through the target coordinate area based on the target modulation signal to obtain phase-modulated light; the polarized light is natural light passing through the first polarizer; after the phase-modulated light is amplitude-modulated by polarization analysis of the second polarizer, the rear mirror assembly images the amplitude-modulated light onto the imaging detector to obtain a target image; and the grayscale values ​​of the pixels in the target grid area of ​​the target image are within a preset grayscale range. The system can phase modulate the incident light through the cooperation of the first polarizer and the spatial light modulator, and ultimately achieve amplitude modulation through the second polarizer, greatly improving the dynamic range of the system; moreover, the system can perform one-time phase modulation on the polarized light in the entire target coordinate area, realizing one-time modulation of the light intensity at different spatial positions in the light field, significantly improving the modulation efficiency.

[0127] Regarding the apparatus in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0128] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, which can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0129] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the following claims.

[0130] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. An imaging method, characterized in that: The method is applied to an imaging optical system, which includes a controller and a front mirror group, a spatially tunable component, a rear mirror group, and an imaging detector placed in sequence; the controller is electrically connected to the spatially tunable component and the imaging detector, and the optical axes of the front mirror group, the spatially tunable component, the rear mirror group, and the imaging detector respectively coincide with the main optical axis of the system; The front lens group is composed of at least one group of lenses, and is used to image the target object on a primary image plane; The spatially tunable component is located on the primary image plane, and includes a first polarizer, a liquid crystal spatial light modulator, and a second polarizer placed in sequence; the first polarizer is used to polarize the natural light emitted by the target object to obtain polarized light; the liquid crystal spatial light modulator is used to phase-modulate the polarized light in the target coordinate area after receiving the target modulation signal from the controller to obtain phase-modulated light; the second polarizer is used to analyze the phase-modulated light to obtain amplitude-modulated light; The rear mirror group is composed of at least one group of lenses, and is used to image the amplitude modulated light onto a final image plane; The imaging detector is located on the final image plane and is used to receive the target image corresponding to the amplitude modulated light; The method comprises: When the liquid crystal spatial light modulator is in a fully transparent state, the controller acquires an initial image received by the imaging detector; The controller divides the initial image into a plurality of grid areas of equal area; The controller obtains the grayscale value of each pixel in each of the grid areas, and determines a target grid area requiring grayscale modulation from the plurality of grid areas based on the grayscale value; The controller determines, based on a spatial mapping relationship between the photosensitive surface of the imaging detector and the liquid crystal spatial light modulator, that the target grid area corresponds to a target coordinate area on the liquid crystal spatial light modulator; The controller generates a target modulation signal according to the grayscale value of the target coordinate area; The liquid crystal spatial light modulator adjusts the phase of the polarized light passing through the target coordinate area according to the target modulation signal to obtain phase modulated light; the polarized light is natural light passing through the first polarizer; After the phase modulated light is amplitude modulated by the analyzer of the second polarizer, the rear mirror group images the amplitude modulated light onto the imaging detector to obtain a target image; the grayscale values ​​of the pixels in the target network area of ​​the target image are within a preset grayscale range.

2. The method according to claim 1, characterized in that The liquid crystal spatial light modulator is a reflective liquid crystal spatial light modulator or a transmissive liquid crystal spatial light modulator.

3. The method according to claim 1, characterized in that The front mirror group includes at least one of a first reflective mirror and a first transmissive mirror, and the rear mirror group includes at least one of a second reflective mirror and a second transmissive mirror.

4. The method according to claim 2, characterized in that When the liquid crystal spatial light modulator is a reflective liquid crystal spatial light modulator, the main optical axis of the system is a broken line, and the second polarizer, the rear mirror group, and the imaging detector are arranged on the reflected light path of the reflective liquid crystal spatial light modulator; When the liquid crystal spatial light modulator is a transmissive liquid crystal spatial light modulator, the main optical axis of the system is a straight line, and the front mirror group, the first polarizer, the transmissive liquid crystal spatial light modulator, the second polarizer, the rear mirror group and the imaging detector are arranged on a straight line.

5. The method according to claim 1, wherein The determining, based on the grayscale value, a target grid area requiring grayscale modulation from the plurality of grid areas comprises: For each of the grid areas in the initial image, counting a first number of first pixel points whose grayscale values ​​are less than or equal to a preset first grayscale threshold; If there is a first grid area where the first number is greater than a preset target number, sending a parameter adjustment instruction to the imaging detector, the parameter adjustment instruction including a target parameter and a target value of the target parameter; the target parameter being an initial parameter related to a response amplitude of the imaging detector; The imaging detector adjusts the target parameter to the target value according to the parameter adjustment signal, so that the imaging detector displays a first image; the first image is an image in each grid area where the first number is smaller than the target number; For each of the grid areas in the first image, counting a second number of pixels having a grayscale value greater than a preset second grayscale threshold; The second grid areas whose second number is greater than the target number are determined as target grid areas.

6. The method according to claim 5, characterized in that After counting the first number of first pixel points whose grayscale values ​​are less than or equal to the preset first grayscale threshold, the method further includes: If there is no first grid area whose first number is greater than the preset target number, then for each of the grid areas in the initial image, counting a second number of second pixel points whose grayscale values ​​are greater than a preset second grayscale threshold; The second grid areas whose second number is greater than the target number are determined as target grid areas.

7. The method according to claim 6, characterized in that The target modulation signal includes a target rotation angle of liquid crystal molecules in the target coordinate area, and the liquid crystal spatial light modulator adjusts the phase of polarized light in the target coordinate area according to the target modulation signal, including: The liquid crystal spatial light modulator controls the liquid crystal molecules in the target coordinate area to rotate according to the target rotation angle according to the target modulation signal, so that the phase of the polarized light passing through the target coordinate area is adjusted.

8. The method according to claim 5, characterized in that The preset grayscale range is between the first grayscale threshold and the second grayscale threshold.

9. The method according to claim 4, characterized in that Before the controller acquires the initial image received by the imaging detector, the method further includes: After the system is powered on, the liquid crystal spatial light modulator sets the rotation angles of all liquid crystal molecules to the initial angles, so that the spatial light modulator is in a fully transparent state; the fully transparent state is a state with the highest transmittance of natural polarized light; The rear mirror assembly images the target object located in front of the front mirror assembly onto the imaging detector; The imaging detector receives an initial image corresponding to the target object.

Images