Scanning dot matrix light field display system

Abstract

The invention discloses a scanning dot matrix light field display system, which relates to the field of light field display and comprises a laser generation module, a light modulator, a bidirectional scanning galvanometer, a periodic Z-axis electric control zoom lens, a medium excitation module and a central control module. According to the invention, the heat accumulation effect is avoided through the short pulse characteristic of the pulse laser, the space scanning capability of the galvanometer-zoom system is combined, a voxel array capable of being dynamically refreshed is constructed in the air, a suspension light field image capable of being dynamically reconstructed is directly generated, and the physical limitation that the traditional display technology depends on an entity screen is broken through; the first fixed frequency and the second fixed frequency are adopted for the bidirectional scanning galvanometer and the periodic Z-axis electric control zoom lens respectively, the galvanometer does not need to be regulated and controlled in the mode, the speed of the galvanometer can be greatly increased, the number of scanning dot matrixes can be increased, the system can be simplified, and miniaturization of the imaging system can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of light field display, and in particular to a scanning dot matrix light field display system. Background Art

[0002] Traditional 3D display technology has the following limitations: 1. Volumetric 3D display devices rely on rotating screens or layered projection, which can lead to fragile moving parts and limited refresh rates.

[0003] 2. Holographic projection has defects such as complex calculations, limited viewing angle, and difficulty in achieving true color display.

[0004] 3. Existing light field display technology is limited by insufficient spatial bandwidth product, making it difficult to simultaneously meet the requirements of wide viewing angle, large depth of field, and high definition. The technology development has entered a bottleneck period, and the presentation of three-dimensional images cannot be separated from the screen.

[0005] 4. Existing laser scanning 3D display technology does not regulate MHz-level femtosecond laser pulses, but instead performs coding regulation on the scanning galvanometer. This regulation mode requires control of the galvanometer scanning path, resulting in the scanning frequency being limited to the kHz level. As a result, the number of dots in the scanned 3D image is severely restricted, and the advantage of the laser MHz-level repetition frequency is not effectively utilized. Summary of the Invention

[0006] In response to the above-mentioned deficiencies in the prior art, the present invention provides a scanning dot matrix light field display system that solves the problem that the existing laser scanning three-dimensional display technology does not regulate the MHz-level femtosecond laser pulses, resulting in a serious restriction on the number of dots in the scanned three-dimensional image.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: Provided is a scanning dot matrix light field display system, which includes a laser generating module, a light modulator, a bidirectional scanning galvanometer, a periodic Z-axis electrically controlled zoom lens, a medium excitation module and a central control module; Laser generating module, used for generating laser pulses; The central control module is used to convert the coordinate data of the input three-dimensional image into a "01" code stream and form a control signal; An optical modulator is used to control the on-off of laser pulses according to a control signal to form a MHz optical switch, thereby selecting laser pulses and outputting the selected laser pulses; A bidirectional scanning galvanometer is used to receive the selected laser pulses and perform resonant motion at a set first fixed frequency, synthesizing the scanning trajectory of the X-axis and the scanning trajectory of the Y-axis to achieve two-dimensional scanning coverage and output the scanned laser beam; A periodic Z-axis electrically controlled zoom lens is used to periodically adjust the focal length of the scanned laser beam using a set second fixed frequency, and output a laser beam that can form a focused spot at a preset spatial position; The medium excitation module is used to be excited at the focus point by a laser beam that can form a focused spot at a preset spatial position and generate visible light radiation, thereby forming an image display.

[0008] Furthermore, the laser generating module is a 1050nm or 1330nm femtosecond fiber laser, and the laser pulses generated by the laser generating module are infrared pulse sequences with a repetition frequency of 10MHz, and the wavelength is within the human eye-safe band.

[0009] Furthermore, the central control module is also used to perform timing calibration on the laser generating module, the bidirectional scanning galvanometer and the periodic Z-axis electrically controlled zoom lens, mapping the three-dimensional spatial coordinates into the galvanometer deflection angle of the bidirectional scanning galvanometer and the focal length value of the periodic Z-axis electrically controlled zoom lens.

[0010] Furthermore, the specific method of converting the input coordinate data of the three-dimensional image into a "01" code stream includes the following steps: Decompose the three-dimensional image into a number of voxels, and convert the voxels into luminous points to form a three-dimensional luminous point matrix; Determine the three-dimensional coordinates of each light-emitting point to form a three-dimensional light-emitting point position information array; The three-dimensional coordinates of each light-emitting point are converted into the corresponding scanning angle and zoom parameter. The corresponding expression is:

[0011]

[0012]

[0013] in 、 and They are the scanning angle of X axis, the scanning angle of Y axis and the zoom parameter; is the three-dimensional coordinate of the light-emitting point; 、 and are the scale factors in the X, Y and Z axis directions respectively; 、 and They are the offsets in the X, Y and Z axis directions respectively; is a constant; Determine the time coordinate of the beam pulse according to the scanning angle and zoom parameters; Determine whether the three-dimensional luminous dot matrix position focused on the time coordinate needs to be lit. If so, assign 1 to the binary information at the time coordinate of the code stream, otherwise assign 0 to it, and then obtain a "01" code stream; The "01" code stream is modulated into the carrier to form a control signal.

[0014] Furthermore, the expression for determining the time coordinate of the beam pulse according to the scanning angle and zoom parameter is:

[0015] in Represents the beam pulse Time coordinates; 、 and Respectively The horizontal scanning angle at the moment, The vertical scanning angle at the moment and The focal length of the moment; 、 and Respectively represent the horizontal scanning angular velocity, vertical scanning angular velocity and focusing speed; Indicates taking the maximum value.

[0016] Furthermore, the optical modulator is an acousto-optic modulator, an electro-optical modulator or an optical-optical modulator; the optical modulator changes its internal diffraction characteristics according to the "01" code stream, so that the diffraction order of the laser pulse after passing through the optical modulator changes, thereby realizing the controlled change of zero-order light and first-order light, so that the optical modulator loaded with the control signal forms a high-speed optical switch, and then selects the laser pulse and outputs the selected laser pulse.

[0017] Furthermore, by establishing a mapping relationship between the two-dimensional scanning angle and the plane coordinates of the target space voxel, the accuracy of the bidirectional scanning galvanometer is ensured to reach the micro-radian level.

[0018] Furthermore, the bidirectional scanning galvanometer and the periodic Z-axis electrically controlled zoom lens operate synchronously, and the first fixed frequency and the second fixed frequency are the same, both being 1 kHz.

[0019] Furthermore, conversion fluorescent dust containing rare earth ions is evenly distributed in the medium excitation module. When the peak power density of the laser beam that can form a focused spot at a preset spatial position exceeds the excitation threshold of the conversion fluorescent dust containing rare earth ions, the rare earth ions realize energy up-conversion through a multi-photon absorption process, converting the infrared photons in the laser beam that can form a focused spot at the preset spatial position into visible light radiation, thereby forming an image display.

[0020] Furthermore, pixel brightness grading control is achieved by adjusting the light emitting power of the laser generating module.

[0021] The beneficial effects of the present invention are: 1. A first fixed frequency and a second fixed frequency are respectively used for the bidirectional scanning galvanometer and the periodic Z-axis electric-controlled zoom lens. This method does not require adjustment of the galvanometer, can greatly increase the speed of the galvanometer, increase the number of scanning points, and can simplify the system to achieve miniaturization of the imaging system.

[0022] 2. This system utilizes the short pulse characteristics of pulsed lasers to avoid heat accumulation effects. Combined with the spatial scanning capabilities of a galvanometer-zoom system, it constructs a dynamically refreshable voxel array in air. This upconversion luminescence mechanism avoids interference from visible light backgrounds while directly generating dynamically reconstructible suspended light field images in three-dimensional space. This overcomes the physical limitations of traditional display technologies that rely on physical screens, achieving true three-dimensional light field display with a 360° viewing angle.

[0023] 3. The voxel refresh rate of this system can reach 30Hz, supporting dynamic image display.

[0024] 4. The number of voxels in a single-frame three-dimensional light field image of this system is expected to exceed 30,000.

[0025] 5. This system uses up-conversion to excite conversion fluorescent dust containing rare earth ions. Compared with the conventional laser light field display scheme that ionizes and breaks down the medium to form plasma, it has higher luminous efficiency and lower power consumption, which can effectively improve the safety of this system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the structural block diagram of this system. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0028] like Figure 1 As shown, the scanning dot matrix light field display system includes a laser generating module, a light modulator, a bidirectional scanning galvanometer, a periodic Z-axis electrically controlled zoom lens, a medium excitation module and a central control module; Laser generating module, used for generating laser pulses; The central control module is used to convert the coordinate data of the input three-dimensional image into a "01" code stream and form a control signal; An optical modulator is used to control the on-off of laser pulses according to a control signal to form a MHz optical switch, thereby selecting laser pulses and outputting the selected laser pulses; A bidirectional scanning galvanometer is used to receive the selected laser pulses and perform resonant motion at a set first fixed frequency, synthesizing the scanning trajectory of the X-axis and the scanning trajectory of the Y-axis to achieve two-dimensional scanning coverage and output the scanned laser beam; A periodic Z-axis electrically controlled zoom lens is used to periodically adjust the focal length of the scanned laser beam using a set second fixed frequency, and output a laser beam that can form a focused spot at a preset spatial position; The medium excitation module is constructed in space and is used to be excited at the focal point by a laser beam that can form a focused spot at a preset spatial position and generate visible light radiation, thereby forming an image display.

[0029] The central control module is also used to perform timing calibration on the laser generation module, the bidirectional scanning galvanometer and the periodic Z-axis electric-controlled zoom lens, and map the three-dimensional spatial coordinates into the galvanometer deflection angle of the bidirectional scanning galvanometer and the focal length value of the periodic Z-axis electric-controlled zoom lens.

[0030] In this embodiment, the x- and y-axis scanning mirrors vibrate at a fixed frequency, without any signal control. The mirrors are coated to increase their damage threshold. The periodic z-axis electrically controlled zoom lens also adjusts focus at a fixed frequency, without any signal control. This lens can be either transmissive or refractive.

[0031] The laser generation module is a 1050nm or 1330nm femtosecond fiber laser. The laser pulses generated by the laser generation module are infrared pulse sequences with a repetition frequency of 10MHz. The wavelength is within the human eye-safe band. By adjusting the luminous power of the laser generation module, pixel brightness can be controlled in stages. An electro-optic modulator with a maximum response frequency of 10Mhz is selected; a 1kHz scanning galvanometer with a silver-plated surface is selected for biaxial scanning, and the zoom lens frequency is 1KHz. The image is displayed in an area of ​​10cm×10cm×10cm. The three-dimensional coordinate points are determined based on the center of the image. Let the position of each luminous point that constitutes the image be , assuming the system is telecentric (i.e., changes in the scanning mirror angle do not significantly affect the Z direction), and ignoring higher-order aberrations (such as field curvature and distortion), Direction (controlled by X-axis scanning galvanometer): ; Direction (controlled by Y-axis scanning galvanometer): ; Direction (controlled by electronically controlled focus lens): .in is the focusing distance of the electronically controlled focus lens.

[0032] In this embodiment, the specific method of converting the coordinate data of the input three-dimensional image into a "01" code stream includes the following steps: A1. Decompose the three-dimensional image into a number of voxels, and convert the voxels into luminous points to form a three-dimensional luminous point matrix; A2. Determine the three-dimensional coordinates of each light-emitting point to form a three-dimensional light-emitting point position information array; A3. Convert the three-dimensional coordinates of each light-emitting point into the corresponding scanning angle and zoom parameter. The corresponding expression is:

[0033]

[0034]

[0035] in 、 and They are the scanning angle of X axis, the scanning angle of Y axis and the zoom parameter; is the three-dimensional coordinate of the light-emitting point; 、 and are the scale factors in the X, Y and Z axis directions respectively; 、 and The offsets in the X, Y, and Z axes represent the position of the system zero or reference point, which can usually be set to 0 after calibration. is a constant used to determine the image size; and Depends on the focal length and optical magnification of the scan lens. Depends on the optical system configuration (such as the relative positions of the scan lens and focus lens). All angles are in radians (rad).

[0036] A4. Determine the time coordinate of the beam pulse according to the scanning angle and zoom parameter; A5. Determine whether the three-dimensional luminous dot matrix position focused at the time coordinate needs to be illuminated. If so, assign 1 to the binary information at the time coordinate of the code stream; otherwise, assign 0 to obtain a "01" code stream. A6. Modulate the "01" code stream into the carrier to form a (microsecond / nanosecond) control signal.

[0037] The expression for determining the time coordinate of the beam pulse based on the scanning angle and zoom parameter is:

[0038] The core logic of this expression is to determine the specific pulse time selection in combination with the display requirements. After the pulse time is selected, each pulse can be coded 01. This 01 code can be used to 、 、 Control and thus realize lighting of different points in the space.

[0039] in Represents the beam pulse Time coordinates; 、 and Respectively The horizontal scanning angle at the moment, The vertical scanning angle at the moment and The focal length of the moment; 、 and Respectively represent the horizontal scanning angular velocity, vertical scanning angular velocity and focusing speed; Indicates taking the maximum value.

[0040] Optionally, the optical modulator is an acousto-optic modulator, an electro-optical modulator or an optical-optical modulator; the optical modulator changes its internal diffraction characteristics according to the "01" code stream, so that the diffraction order of the laser pulse after passing through the optical modulator changes, thereby realizing the controlled change of zero-order light and first-order light, so that the optical modulator loaded with the control signal forms a high-speed optical switch (the control of the energy difference can make the optical modulator loaded with the control signal form a high-speed optical switch, reaching the MHz level), and then selects the laser pulse and outputs the selected laser pulse.

[0041] In this embodiment, the mapping relationship between the two-dimensional scanning angle and the plane coordinates of the target space voxel can be established to ensure that the accuracy of the bidirectional scanning galvanometer reaches the micro-radian level. The bidirectional scanning galvanometer works synchronously with the periodic Z-axis electrically controlled zoom lens, and the first fixed frequency is the same as the second fixed frequency. The synchronously working periodic Z-axis electrically controlled zoom lens group adjusts the focal length according to the fixed frequency, so that the laser beam forms a focused light spot at a preset spatial position. The bidirectional scanning galvanometer and the periodic Z-axis electrically controlled zoom lens group use a fixed frequency for periodic scanning control, and do not use non-periodic electrical signal encoding to control their trajectory. Doing so can greatly increase the speed of the galvanometer, increase the number of scanning points, and simplify the system to achieve miniaturization of the imaging system.

[0042] Conversion fluorescent dust containing rare earth ions is evenly distributed in the medium excitation module. When the peak power density of the laser beam that can form a focused spot at a preset spatial position exceeds the excitation threshold of the conversion fluorescent dust containing rare earth ions, the rare earth ions achieve energy upconversion through the multi-photon absorption process, converting the infrared photons in the laser beam that can form a focused spot at the preset spatial position into visible light radiation, thereby forming an image display.

[0043] In this embodiment, the process of converting the coordinate data of the input three-dimensional image into a "01" code stream for the first time is as follows: (1) Construct a two-dimensional test first square image perpendicular to the periodic Z-axis electric zoom lens in space, correct the test code stream, and construct a scanning matching relationship between the code stream and the periodic Z-axis electric zoom lens; (2) Correct the test code stream with a square image perpendicular to the first square image in space, and establish a matching relationship between the code stream and the bidirectional scanning galvanometer; (3) Construct a cube image in space and complete the periodic alignment correction of the code stream; (4) According to the correction results, the 3D image to be displayed is time-sequentially decomposed, mapped into a string of binary code streams, and converted into signals to be input into the optical modulator.

[0044] In practice, the central control module coordinates the work of various components through a time synchronization system, mapping 3D spatial coordinates into three control parameters: the galvanometer deflection angle, the focal length of the electrically controlled adjustable lens, and the code stream signal of the light modulator, while maintaining timing alignment. The system sequentially scans and excites fluorescent voxels point by point in 3D space, leveraging the human eye's persistence of vision (>30Hz refresh rate) to form a continuous voxel matrix. When the scanning speed exceeds the human eye's perception, the discrete voxel points are integrated into a continuous 3D light field image in the observer's visual system.

[0045] In this embodiment, the medium excitation module can be directly constructed in the space by dispersing powder (conversion fluorescent dust containing rare earth ions) in the air. The powder only needs to be treated with low toxicity or non-toxicity.

[0046] In summary, the present invention avoids the heat accumulation effect by utilizing the short pulse characteristics of pulsed lasers, and combines the spatial scanning capability of the galvanometer-zoom system to construct a dynamically refreshable voxel array in the air, directly generating a dynamically reconstructable suspended light field image, thus breaking through the physical limitations of traditional display technology that relies on a physical screen. The present invention adopts a first fixed frequency and a second fixed frequency for the bidirectional scanning galvanometer and the periodic Z-axis electrically controlled zoom lens, respectively. This method does not require the galvanometer to be adjusted, can greatly increase the speed of the galvanometer, increase the number of scanning points, and can simplify the system, thereby realizing the miniaturization of the imaging system. This system can be applied to three-dimensional visualization of medical images, industrial precision detection, augmented reality interactive interfaces, and anti-interference display in special environments.

Claims

1. A scanning dot matrix light field display system, characterized in that: It includes a laser generating module, a light modulator, a bidirectional scanning galvanometer, a periodic Z-axis electrically controlled zoom lens, a medium excitation module and a central control module; Laser generating module, used for generating laser pulses; The central control module is used to convert the coordinate data of the input 3D image into a "01" code stream and form a control signal; An optical modulator is used to control the on-off of laser pulses according to a control signal to form a MHz optical switch, thereby selecting laser pulses and outputting the selected laser pulses; A bidirectional scanning galvanometer is used to receive the selected laser pulses and perform resonant motion at a set first fixed frequency, synthesizing the scanning trajectory of the X-axis and the scanning trajectory of the Y-axis to achieve two-dimensional scanning coverage and output the scanned laser beam; A periodic Z-axis electrically controlled zoom lens is used to periodically adjust the focal length of the scanned laser beam using a set second fixed frequency, and output a laser beam that can form a focused spot at a preset spatial position; The medium excitation module is used to be excited at the focus point by a laser beam that can form a focused spot at a preset spatial position and generate visible light radiation, thereby forming an image display.

2. The scanning dot matrix light field display system according to claim 1, characterized in that: The laser generation module is a 1050nm or 1330nm femtosecond fiber laser. The laser pulses generated by the laser generation module are infrared pulse sequences with a repetition frequency of 10MHz, and the wavelength is in the eye-safe band.

3. The scanning dot matrix light field display system according to claim 1, characterized in that: The central control module is also used to perform timing calibration on the laser generation module, the bidirectional scanning galvanometer and the periodic Z-axis electric-controlled zoom lens, and map the three-dimensional spatial coordinates into the galvanometer deflection angle of the bidirectional scanning galvanometer and the focal length value of the periodic Z-axis electric-controlled zoom lens.

4. The scanning dot matrix light field display system according to claim 1, characterized in that: The specific method of converting the coordinate data of the input three-dimensional image into a "01" code stream includes the following steps: Decompose the three-dimensional image into a number of voxels, and convert the voxels into luminous points to form a three-dimensional luminous point matrix; Determine the three-dimensional coordinates of each light-emitting point to form a three-dimensional light-emitting point position information array; The three-dimensional coordinates of each light-emitting point are converted into the corresponding scanning angle and zoom parameter. The corresponding expression is: in 、 and They are the scanning angle of X axis, the scanning angle of Y axis and the zoom parameter; is the three-dimensional coordinate of the light-emitting point; 、 and are the scale factors in the X, Y and Z axis directions respectively; 、 and They are the offsets in the X, Y and Z axis directions respectively; is a constant; Determine the time coordinate of the beam pulse according to the scanning angle and zoom parameters; Determine whether the three-dimensional luminous dot matrix position focused on the time coordinate needs to be lit. If so, assign 1 to the binary information at the time coordinate of the code stream, otherwise assign 0 to it, thereby obtaining a "01" code stream; The "01" code stream is modulated into the carrier to form a control signal.

5. The scanning dot matrix light field display system according to claim 4, characterized in that: The expression for determining the time coordinate of the beam pulse based on the scanning angle and zoom parameter is: in Represents the beam pulse Time coordinates; 、 and Respectively The horizontal scanning angle at the moment, The vertical scanning angle at the moment and The focal length of the moment; 、 and Respectively represent the horizontal scanning angular velocity, vertical scanning angular velocity and focusing speed; Indicates taking the maximum value.

6. The scanning dot matrix light field display system according to claim 1, characterized in that: The optical modulator can be an acousto-optic modulator, an electro-optical modulator, or an optical-optical modulator. The optical modulator changes its internal diffraction characteristics according to the "01" code stream, causing the diffraction order of the laser pulse after passing through the optical modulator to change, achieving controlled changes between zero-order light and first-order light. The optical modulator loaded with the control signal forms a high-speed optical switch, thereby selecting and outputting the selected laser pulse.

7. The scanning dot matrix light field display system according to claim 1, characterized in that: By establishing a mapping relationship between the two-dimensional scanning angle and the plane coordinates of the target space voxel, the accuracy of the bidirectional scanning galvanometer is ensured to reach the micro-radian level.

8. The scanning dot matrix light field display system according to claim 1, characterized in that: The bidirectional scanning galvanometer and the periodic Z-axis electric-controlled zoom lens work synchronously, and the first fixed frequency and the second fixed frequency are the same, both of which are 1 kHz.

9. The scanning dot matrix light field display system according to claim 1, characterized in that: Conversion fluorescent dust containing rare earth ions is evenly distributed in the medium excitation module. When the peak power density of the laser beam that can form a focused spot at a preset spatial position exceeds the excitation threshold of the conversion fluorescent dust containing rare earth ions, the rare earth ions achieve energy upconversion through the multi-photon absorption process, converting the infrared photons in the laser beam that can form a focused spot at the preset spatial position into visible light radiation, thereby forming an image display.

10. The scanning dot matrix light field display system according to claim 1, characterized in that: Pixel brightness grading control is achieved by adjusting the luminous power of the laser generating module.

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