Micro-scanning holographic imager

Abstract

The present invention relates to the field of 3D imaging, and discloses a micro-scanning holographic imager, including a two-dimensional imaging element, at least one galvanometer, an imaging mirror group, and a depth-of-focus scanning mechanism, which are respectively arranged inside the holographic imager; the position of the galvanometer corresponds to the two-dimensional display element, and is used to optically transform light and form an equivalent image plane; the position of the imaging mirror group corresponds to the two-dimensional imaging element, and is used to optically transform light and form a two-dimensional picture; the depth-of-focus scanning mechanism is connected to the galvanometer, and is used to control the spatial position change of the galvanometer to realize volume scanning of the two-dimensional picture. The present invention realizes periodic volume scanning (Bragg period scanning) of the projection picture by introducing a depth-of-focus scanning mechanism and multiple galvanometers, greatly reduces the amplitude of the volume scanning, and increases the scanning frequency, and can stably realize 3D imaging / projection display functions with ultra-high resolution and ultra-fast frame rate.

Description

Technical Field

[0001] The present invention relates to the field of 3D imaging, and in particular to a micro-scanning holographic imager. Background Art

[0002] 3D display technology can provide additional depth information on the basis of traditional two-dimensional display, so it is considered to be the development direction of the next generation of display technology. However, there is no more effective solution to achieve 3D display. Most of the successful commercial cases are pseudo-3D technologies based on stereo image pairs, which cannot provide users with real 3D images with depth information. For example, the principle of 3D movies in movie theaters is to use a projector to project two two-dimensional left and right eye image pairs on the screen. By wearing selective filtering glasses, the two eyes receive different images, thus giving people the illusion of seeing a 3D image, but in fact the projected image is only a 2D image. Long-term viewing can also cause eye discomfort.

[0003] Volume scanning imaging can achieve true 3D effects and is a very promising 3D solution. However, volume scanning imaging 3D often requires a high-speed rotating / moving screen, and the system has major safety risks, poor stability, very limited display space, no direct touch interaction, and the display screen is transparent, unable to express the correct occlusion relationship.

[0004] Patents with authorization numbers CN106773469B, CN 207114903U and CN 206431409U disclose a solution that can achieve true 3D display. Its key component is a stereoscopic display module, which can achieve true 3D image reproduction through depth scanning. Its working principle is to make a focal plane scan back and forth in the depth direction (depth scanning) to form a continuous 3D image. In this way, although the projection of 3D images can be achieved, it relies on the scanning imaging of a single focal plane, and the movement speed of the mechanical structure of the display system is extremely high. The reliability of the system cannot be guaranteed, and the refresh speed and overall brightness of the picture cannot be optimized. At the same time, the calculation and control system are extremely complex, and it is difficult to achieve stable picture display, and the manufacturing cost is extremely high. In this way, the reliability of the system is difficult to guarantee, and the vibration resistance of the imaging chip itself is very limited. Even ordinary collisions or falls may cause damage. Similarly, the position accuracy of the imaging lens itself needs to be very difficult to stabilize. Once it deviates too far from the ideal assembly position, it will seriously affect the imaging quality.

[0005] An all-solid-state holographic projector with application number 202010029144.5 realizes an all-solid-state holographic display effect by setting multiple discrete focal planes in a projector. However, the 3D picture formed in this way is not continuous, and the slice-like pictures in the real space cannot fully realize the continuous 3D picture. At the same time, there are limited display space, inability to correctly express occlusion relationships, safety hazards, and poor system reliability. In addition, there are problems such as bulky equipment and large application restrictions. Summary of the invention

[0006] The technical problem to be solved by the present invention is: in view of the shortcomings of the above-mentioned prior art, a micro-scanning holographic imager is provided, which realizes periodic volume scanning of the imaging picture by introducing a focal depth scanning mechanism and multiple galvanometer mirrors, greatly reduces the amplitude of the volume scanning, and increases the scanning frequency, so as to stably realize 3D imaging / projection display functions with ultra-high resolution and ultra-fast frame rate.

[0007] In order to solve the above technical problems, the present invention proposes a micro-scanning holographic imager, comprising:

[0008] Two-dimensional imaging element;

[0009] At least one galvanometer mirror, whose position corresponds to the two-dimensional imaging element, is used to optically transform the light and form an equivalent image plane;

[0010] An imaging lens group, whose position corresponds to the equivalent image plane, is used to optically transform the light and form a two-dimensional image; and

[0011] The focal depth scanning mechanism is connected to the galvanometer and is used to control the spatial position change of the galvanometer to realize volume scanning of a two-dimensional image.

[0012] Furthermore, the focal depth scanning mechanism is also connected to the two-dimensional imaging element and / or the imaging lens group respectively, and is used to control the spatial position change of the two-dimensional imaging element and / or the imaging lens group to achieve volume scanning of the two-dimensional image.

[0013] Furthermore, the focal depth scanning mechanism is also connected to the imaging lens group to control the change of the effective focal length of the imaging lens group to achieve volume scanning of the two-dimensional image.

[0014] Furthermore, the imaging lens assembly at least includes a liquid variable focus lens or a flexible variable focus lens.

[0015] Furthermore, the number of the galvanometers is N, and the mass of any one of the galvanometers is M. N g, the amplitude is A mm, the mass of the outermost lens of the holographic imager is mg, and it satisfies:

[0016] Furthermore, the scanning frequency of the focal depth scanning mechanism is greater than 6 Hz.

[0017] Furthermore, the two-dimensional imaging element is a projection display element or a photographing photosensitive element.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] 1. The present invention replaces the traditional high-speed large-range scanning device with micro-scanning. The device is extremely small, the effective display space is extremely large, and there is no safety problem caused by high-speed moving parts;

[0020] 2. The scanning components are encapsulated inside, not in contact with the outside world, and not easily damaged;

[0021] 3. When the present invention is used, the eyes need to dynamically adjust the focal depth just like viewing real objects, rather than the fixed focal depth of ordinary 2D display images, so it will not cause visual fatigue and help protect eyesight;

[0022] 4. The present invention can realize the projection and shooting functions at the same time, which is convenient for outputting picture information and receiving external image information in real time during practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a schematic diagram of the system of the imager of the present invention and embodiment 1 in which the two-dimensional imaging element 1 is a projection display element,

[0025] Figure 2 is Figure 1 Based on the above, the system diagram of the imager of the present invention is a diagram in which the projection display element is replaced by a photographing photosensitive element.

[0026] Figure 3 is a system schematic diagram of Example 2,

[0027] Figure 4 is a system schematic diagram of Example 3,

[0028] Figure 5 is a system schematic diagram of Example 4,

[0029] Figure 6 is a schematic diagram of a vibration cycle of the equivalent image plane 3,

[0030] Figure 7 It is a schematic diagram of the principle of mechanical zooming of the imaging lens group 4.

[0031] Figure 8 The figure is a schematic diagram of the zoom principle of the imaging lens group 4 using a flexible zoom lens.

[0032] Fig. 9 This is a schematic diagram of the corresponding relationship between the vibration amplitudes of the galvanometer 2 and the two-dimensional imaging element 1 when the angle between the two is 45°.

[0033] Fig.10 is a system schematic diagram of the imager of the present invention when the number of the galvanometer mirrors 2 is 2,

[0034] The reference numerals are as follows:

[0035] Two-dimensional imaging element 1, galvanometer 2, equivalent image plane 3, imaging lens group 4, two-dimensional picture 5, depth of focus scanning mechanism 6. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings. The description in this part is only exemplary and explanatory and should not have any limiting effect on the protection scope of the present invention.

[0037] Reference Figures 1 to 10 The present invention provides a micro-scanning holographic imager, comprising a two-dimensional imaging element 1, at least one galvanometer 2, an imaging lens group 4 and a focal depth scanning mechanism 6 respectively arranged therein;

[0038] The galvanometer 2 is arranged at a position corresponding to the two-dimensional imaging element 1, and is used to optically transform the light and form an equivalent image plane 3;

[0039] The position of the imaging lens group 4 corresponds to the equivalent image plane 3, and is used to optically transform the light and form a two-dimensional image 5;

[0040] The focal depth scanning mechanism 6 is connected to the galvanometer 2 and is used to control the spatial position change of the galvanometer 2 to achieve volume scanning of the two-dimensional image 5;

[0041] The two-dimensional imaging element 1 of the present invention can be a projection display element or a photographing photosensitive element:

[0042] like Figure 1When the two-dimensional imaging element 1 is a projection display element, the projection light of the projection display element is optically transformed by the galvanometer 2 and the imaging lens group 4 in sequence to project a two-dimensional picture 5 in space, which is equivalent to the imaging effect of an equivalent image plane 3 after being projected by the imaging lens group 4. The focal depth scanning mechanism 6 controls the vibration of the galvanometer 2 to change the relative position between the equivalent image plane 3 and the imaging lens group 4, and the two-dimensional picture 5 also vibrates in the focal depth direction to achieve a volume scan of the two-dimensional picture 5, and finally achieve a 3D display effect. The above-mentioned two-dimensional picture 5 and the equivalent image plane 3 are optically conjugate. Therefore, when the two-dimensional picture 5 is volume scanned, the equivalent image plane 3 is also volume scanned at the same time. The above-mentioned two-dimensional picture 5 is a real image plane after optical transformation, and the equivalent image plane 3 is a virtual image plane obtained by optical transformation;

[0043] like Figure 2 When the two-dimensional imaging element 1 is a photographing photosensitive element, according to the reversibility of the optical path, the light of the external scene is optically transformed by the imaging lens group 4 and the galvanometer 2 in sequence, and a two-dimensional picture 5 of a real image is generated on the photographing photosensitive element and recorded, which is equivalent to the imaging effect that the light of the external scene is directly generated by the optical transformation of the imaging lens group 4 and the equivalent image plane 3;

[0044] However, during the imaging process, only the scenes at the optically conjugate depth of field with the shooting photosensitive element or the equivalent image plane 3 can be clearly recorded, and scenes at other depths of field cannot be clearly imaged and recorded. When the depth of focus scanning mechanism 6 controls the vibration of the galvanometer 2, the relative position of the galvanometer 2 and the shooting photosensitive element changes, and the spatial position relationship between the equivalent image plane 3 and the imaging lens group 4 changes periodically (micro scanning). At this time, the depth of field optically conjugate with the shooting photosensitive element or the equivalent image plane 3 also changes periodically, so as to achieve the purpose of depth of field scanning, so that the scenes at different depths of field are imaged and recorded respectively, and 3D shooting is realized. According to the reversible optical path, the depth of field space optically conjugate with the shooting photosensitive chip or the equivalent image plane 3 undergoes periodic scanning, and the equivalent image plane 3 also undergoes corresponding periodic scanning. The above-mentioned equivalent image plane 3 and the two-dimensional picture 5 are in an equivalent relationship. Therefore, scanning the equivalent image plane 2 can be equivalent to scanning the two-dimensional picture 5. The above-mentioned two-dimensional picture 5 is a real image plane after optical transformation, and the equivalent image plane 3 is a virtual image plane obtained by optical transformation.

[0045] The above-mentioned volume scanning is also equivalent to the depth scanning of the 3D image, which can scan out an imaging space to achieve the effect of 3D display.

[0046] Since both the projected two-dimensional image 5 and the photographed two-dimensional image 5 are covered with pixel arrays (two-dimensional), a three-dimensional pixel array can be formed after volume scanning. The advantage of this structure is that a relatively larger equivalent scanning space can be achieved by scanning within a very small range, and the equivalent scanning space can be further enlarged after optical conversion. For example, the motion range of the equivalent image plane 3 is the equivalent scanning range (that is, the area of ​​the equivalent image plane 3 multiplied by 2 times its vertical scanning amplitude, which can be recorded as V 等效 ), and the actual scanning range is the range of motion of the galvanometer 2 (that is, the area of ​​the galvanometer 2 multiplied by twice its vertical scanning amplitude, which can be recorded as V 扫描 ), the ratio of the two is preferably set to be greater than 1.2 (a specific magnification setting mode can be realized through optical geometric relationship, which will not be described here), so as to achieve the purpose of primary magnification, and the optical conversion of the imaging lens group 4 can further enlarge the equivalent scanning range, for example, a lens with a magnification greater than 5 is selected to further enlarge the imaging space to greater than 5 3 times.

[0047] Another advantage of this scanning system is that it can keep key components such as the two-dimensional imaging element 1 and the imaging lens group 4 in a completely static state or in a very slight motion state, thereby making the system more reliable.

[0048] The present invention controls the spatial position change of the galvanometer 2 by setting the focal depth scanning mechanism 6, preferably periodically, to realize the volume scanning of the two-dimensional screen 5, preferably the volume scanning is realized by reciprocating the two-dimensional screen 5. For example, by mechanically performing the periodic reciprocating scanning movement of the galvanometer 2 in the space, a continuous space can be scanned in the space. In practical applications, the scanning can be performed at a fixed frequency, or at different frequencies according to the display content. The design of the scanning mechanism belongs to the common knowledge in the art, and the specific implementation method can be designed according to the actual situation, which will not be described here.

[0049] The effective focal length of the imaging lens group 4 can be further controlled to change periodically by the focal depth scanning mechanism 6, and the volume scanning of the two-dimensional image 5 can also be realized. The effective focal length of the imaging lens group 4 can be changed periodically by changing the relative position and / or the overall position of the optical elements in the imaging lens group 4 (mechanical zoom), or by providing a liquid zoom lens and / or a flexible zoom lens with a zoom function in the imaging lens group 4.

[0050] Furthermore, the depth of focus scanning mechanism 6 can also be connected to the two-dimensional imaging element 1 and / or the imaging lens group 4 respectively, so as to control the spatial position change of the two-dimensional imaging element 1 and / or the imaging lens group 4, realize the volume scanning of the two-dimensional picture 5, and also realize the above-mentioned 3D imaging effect.

[0051] In addition to simple one-dimensional depth of field scanning, three-dimensional scanning can also be used to further improve the display effect. For example, adding scanning parallel to the equivalent image plane can further increase the lateral resolution and make the image quality more delicate.

[0052] The present invention is further described below by taking a two-dimensional imaging element 1 as a projection display element and a micro-scanning holographic imager including only one galvanometer 2 as an example:

[0053] Example 1

[0054] like Figure 1 The micro-scanning holographic imager includes a projection display element, a galvanometer 2, an imaging lens group 4 and a depth of focus scanning mechanism 6 which are respectively arranged inside. The depth of focus scanning mechanism 6 is connected to the galvanometer 2 and controls the reciprocating scanning (or periodic change) of the spatial position of the galvanometer 2, so that the relative position between the equivalent image plane 3 formed by the optical transformation of the galvanometer 2 and the imaging lens group 4 changes periodically, and the position of the two-dimensional picture 5 conjugate with the equivalent image plane 3 also changes periodically along the depth of focus direction, thereby realizing the reciprocating scanning of the two-dimensional picture 5 and presenting a 3D display effect.

[0055] Example 2

[0056] like Figure 3 The micro-scanning holographic imager includes a projection display element, a galvanometer 2, an imaging lens group 4 and a depth of focus scanning mechanism 6 which are respectively arranged inside. The depth of focus scanning mechanism 6 is respectively connected to the projection display element and the galvanometer 2 and controls the periodic change of the spatial positions of the two, so that the relative position between the equivalent image plane 3 formed by the optical transformation of the galvanometer 2 and the imaging lens group 4 changes periodically, and the position of the two-dimensional picture 5 conjugate with the equivalent image plane 3 also changes periodically along the depth of focus direction, thereby realizing the back-and-forth scanning of the two-dimensional picture 5 and presenting a 3D display effect.

[0057] Example 3

[0058] like Figure 4 The micro-scanning holographic imager includes a projection display element, a galvanometer 2, an imaging lens group 4 and a depth of focus scanning mechanism 6 which are respectively arranged inside. The depth of focus scanning mechanism 6 is respectively connected to the galvanometer 2 and the imaging lens group 4 and controls the periodic change of the spatial positions of the two, so that the relative position between the equivalent image plane 3 formed by the optical transformation of the galvanometer 2 and the imaging lens group 4 changes periodically, and the position of the two-dimensional picture 5 conjugate with the equivalent image plane 3 also changes periodically along the depth of focus direction, thereby realizing the back-and-forth scanning of the two-dimensional picture 5 and presenting a 3D display effect.

[0059] Example 4

[0060] like Figure 5The micro-scanning holographic imager includes a projection display element, a galvanometer 2, an imaging lens group 4 and a depth of focus scanning mechanism 6 which are respectively arranged inside. The depth of focus scanning mechanism 6 is respectively connected to the projection display element, the galvanometer 2 and the imaging lens group 4 and controls the periodic change of the spatial positions of the three, so that the relative position between the equivalent image plane 3 formed by the optical transformation of the galvanometer 2 and the imaging lens group 4 changes periodically, and the position of the two-dimensional picture 5 conjugate with the equivalent image plane 3 also changes periodically along the depth of focus direction, thereby realizing the back-and-forth scanning of the two-dimensional picture 5 and presenting a 3D display effect.

[0061] Example 5

[0062] The micro-scanning holographic imager includes a projection display element, a galvanometer 2, an imaging lens group 4 and a depth of focus scanning mechanism 6 which are respectively arranged inside. The depth of focus scanning mechanism 6 is respectively connected to the galvanometer 2 and the imaging lens group 4 and controls the spatial position of the galvanometer 2 and the effective focal depth of the imaging lens group 4 to change periodically, so that the relative position between the equivalent image plane 3 formed by the optical transformation of the galvanometer 2 and the imaging lens group 4 changes periodically, and the position of the two-dimensional picture 5 conjugate with the equivalent image plane 3 also changes periodically along the depth of focus direction, thereby realizing the back-and-forth scanning of the two-dimensional picture 5 and presenting a 3D display effect.

[0063] In Embodiment 5, the focal depth scanning mechanism 6 can control the effective focal depth of the imaging lens assembly 4 in the following manner:

[0064] like Figure 7 The focal depth scanning mechanism 6 controls the relative position and / or the overall position of the multiple optical elements in the imaging lens group 4 to change (mechanical zoom), so as to control the periodic change of the effective focal length of the imaging lens group 4;

[0065] like Figure 8 A flexible zoom lens with a zoom function may be provided in the imaging lens group 4, and the focal length of the flexible zoom lens may be controlled by the focal depth scanning mechanism 6 to achieve control of the periodic change of the effective focal length of the imaging lens group 4. The flexible zoom lens may also be replaced by other lenses with a zoom function, such as a liquid zoom lens, etc.

[0066] Of course, the imaging lens group 4 in the third and fourth embodiments can also be provided with a zoom function, and can be uniformly controlled by the focal depth scanning mechanism 6 to achieve the back-and-forth reciprocating scanning of the two-dimensional image 5. In addition, the number of the galvanometer mirrors 2 can also be multiple, such as Fig. 9 As shown, the number of the galvanometer mirrors 2 is two.

[0067] Embodiments 1 to 5 respectively embody different implementation methods of the back-and-forth scanning of the two-dimensional image 5 , and ultimately all achieve the effect of 3D display.

[0068] According to the principle of reversible optical path, the projection display element in embodiments 1 to 5 can also be replaced by a photographic photosensitive element, such as Figure 2 , in order to achieve the effect of 3D shooting.

[0069] like Figure 6 In actual application of the present invention, when the depth of focus scanning mechanism 6 operates to realize volume scanning of the two-dimensional image 5, the equivalent image plane 3 optically conjugated with the two-dimensional image 5 is also performing volume scanning at the same time;

[0070] The vibration controlled by the focal depth scanning mechanism 6 and the scanning of the equivalent image plane 3 are in a linear correspondence relationship. However, based on the lens imaging law, the scanning of the two-dimensional image 5 in the focal depth direction and the scanning of the equivalent image plane 3 are not in a linear correspondence relationship. Therefore, it is more convenient to design the relevant design parameters with reference to the equivalent image plane 3:

[0071] The amplitude of the equivalent image plane 3 in the focal depth direction (i.e., the maximum displacement of the equivalent image plane 3 from the equilibrium position in the focal depth direction) is L mm. The equilibrium position of the equivalent image plane 3 is the midpoint between the amplitude point in the focal depth direction and the amplitude point in the opposite direction of the focal depth of the equivalent image plane 3. The amplitude point of the equivalent image plane 3 is as follows: Figure 6 As shown, the maximum displacement of the equivalent image plane 3 along the focal depth direction is defined as the focal depth direction amplitude point, and the maximum displacement along the opposite direction of the focal depth is defined as the focal depth opposite direction amplitude point;

[0072] Because of the existence of the galvanometer mirror 2, there should be a geometric correspondence between the amplitude L of the equivalent image plane 3 after the optical transformation of the galvanometer mirror 2 and the amplitude in the vertical direction of the galvanometer mirror 2. The amplitude in the vertical direction of the galvanometer mirror 2 is A mm. It should be noted that the amplitude A in the vertical direction of the galvanometer mirror 2 should be interpreted as the maximum displacement of the galvanometer mirror 2 in the direction perpendicular to itself during the vibration process, and the equilibrium position of the galvanometer mirror 2 is the midpoint position of the maximum displacement in the positive and negative directions of the vibration of the galvanometer mirror 2.

[0073] The amplitude of the galvanometer 2 in the vertical direction is A mm, which is related to the angle between the galvanometer 2 and the two-dimensional imaging element 1. The following takes the angle between the galvanometer 2 and the two-dimensional imaging element 1 as 45° as an example:

[0074] like Fig. 9 As shown, the number of galvanometer mirrors 2 is 1, the amplitude is A mm, and the amplitude L of the volume scan of the equivalent image plane 3 is

[0075] The number of galvanometer mirrors 2 is 2 and they are arranged in parallel with each other, with the same frequency and amplitude of A mm. Then the amplitude L of the volume scan of the equivalent image plane 3 is

[0076] The number of galvanometer mirrors 2 is 3 and they are arranged in parallel with each other, with the same frequency and amplitude of A mm. Then the amplitude L of the volume scan of the equivalent image plane 3 is

[0077] Similarly, if the number of galvanometer mirrors 2 is N and they are arranged in parallel with each other, the frequency is the same, and the amplitude is A mm, then the amplitude L of the volume scan of the equivalent image plane 3 is

[0078] In practical applications, when there are multiple galvanometer mirrors 2 and they are not arranged in parallel, the amplitude L of the equivalent image plane 3 along the focal depth direction can be finally obtained according to geometric calculations;

[0079] In actual applications, in order to present a more delicate picture effect, the volume scanning amplitude can be made larger, or it can be made smaller for scenes that do not require high depth resolution.

[0080] In practical applications, the scanning frequency or equivalent frequency of the depth of focus scanning mechanism 6 is preferably greater than 6 Hz;

[0081] The frequency here refers to the reciprocal of the time interval between two consecutive passes of a certain spatial point by a moving part in the same direction of motion. For example, during the reciprocating scanning process of the galvanometer 2, the reciprocal of the time between two consecutive passes of the equilibrium position of the galvanometer 2 in the same scanning direction. The equilibrium position of the galvanometer 2 has been explained above and will not be repeated here.

[0082] In addition, there is a special case, that is, when the display space moves as a whole, such as moving from a close view to a distant view, the depth of field often only needs one-way movement during the switching process without reciprocating scanning, so there is no concept of depth of field scanning at this time, but the display depth of field switching process also needs to be completed at a relatively appropriate speed, otherwise it is easy to cause picture jumping or tailing. In view of this situation, we introduce the concept of equivalent frequency: equivalent frequency refers to the inverse of the time taken for the equivalent image plane 3 to move unidirectionally relative to the imaging lens group 4, and the movement distance is equal to the amplitude L of the equivalent image plane 3;

[0083] In the case of scanning by zooming, the inverse of the time from the initial focal length to the focal length again during the equivalent focal length change process (or the inverse of the time interval from the maximum focal length to the maximum focal length again) can be used, and the initial focal length refers to the focal length of the imaging lens group 4 when the focal depth scanning mechanism 6 is not in operation. Of course, it is also possible to measure the inverse of the time interval between two consecutive scans of a certain position in the space along the same direction by the projection focal plane.

[0084] When displaying a 3D image in a certain space, the focal plane needs to be scanned back and forth in the certain space to complete the update of the full-space image, so the frame rate of the 3D image is the depth of field scanning frequency.

[0085] The frame rate per second during imaging depends on the scanning frequency. In the actual display process, when the frame rate is greater than 12, the principle of visual persistence of the human eye can be used to form a continuous picture. In addition, in some special occasions, it is necessary to create some stuttering picture effects, so half of the continuous frame rate can achieve this purpose. Therefore, the scanning frequency of the depth of focus scanning mechanism 6 is preferably greater than 6Hz.

[0086] In addition, in order to pursue the best overall display effect, each component needs to be carefully designed.

[0087] On the one hand, it is necessary to improve the wide viewing angle display capability, so the area of ​​the galvanometer 2 should be as large as possible, so as to better utilize the effective optical area of ​​the lens. On the other hand, it is also necessary to ensure excellent depth of field detail performance as much as possible, that is, it is necessary to increase the body scanning frequency. For mechanical scanning systems, the best configuration for scanning is to use its natural frequency for scanning, and usually there is a negative correlation between the natural frequency of the mechanical system and the mass of the vibrating component. Therefore, the mass of the lens needs to be smaller, and its area will be smaller accordingly. In addition, for a product, it is also very important to improve the stability of the system. The smaller the amplitude of vibration during scanning, the closer the system is to solid state, and the better the stability. However, if the amplitude is too small, the depth of field performance range will be restricted, and it is difficult to achieve ultra-large depth of field performance. In addition, if the mass and amplitude of the moving parts are relatively large, the recoil effect on the system will be very obvious, and screen jitter and other situations are prone to occur.

[0088] In summary, for this new solution, it is necessary to consider three mutually contradictory indicators: effective optical utilization area, scanning frequency, and scanning amplitude. However, the three cannot achieve the optimal design at the same time, and certain trade-offs and optimizations are needed to obtain a relatively excellent overall performance.

[0089] Since there is no design experience to draw on, although the imaging principle is relatively easy to understand, it is still difficult to design a product with excellent performance. Therefore, the present invention provides an easy-to-implement design guidance rule to help general practitioners in this field design products with excellent performance.

[0090] Usually for a specific lens imaging application scenario, the thickness range of the main lens is very narrow. For example, for a SLR camera, the thickness of the outermost lens (center thickness) is generally between 1 and 5 mm. In actual conditions, the range will be narrower without considering some extreme special cases, which is mainly restricted by the design rules of the imaging lens. Therefore, the quality of the imaging lens often depends mainly on the size of its aperture. In order to match the imaging lens, the area of ​​the galvanometer 2 also needs to be within a suitable range. In addition, it is also necessary to consider the problem of mirror deformation caused by vibration during the scanning process, that is, the problem of lens stiffness. That is, for a specific area of ​​galvanometer 2, it is necessary to ensure sufficient stiffness by designing its thickness. Therefore, the volume of the scanning mirror is also determined within a very small range. Usually, the material density of the lens is relatively small, so its quality can also be further determined within a reasonable range.

[0091] Through the above theoretical analysis and weighing of various aspects of performance, combined with experimental assembly tests, the present invention determines the parameter design space that can better express the depth of field detail effect under the premise of ensuring a certain viewing angle (since the design of this system is mainly aimed at the 3D imaging field, the depth of field performance ability needs to be prioritized in the design process). The mass of any galvanometer 2 is M N g, the amplitude is A㎜, the mass of the outermost lens of the holographic imager is mg, and it satisfies:

[0092] It should be noted that in the case of using multiple galvanometer mirrors 2, the mass of the scanning lens closest to the outermost lens of the imaging lens is defined as M 1 g, the mass of other scanning lenses is defined as M 2 g、M 3 g、M 4 g……M n g, and satisfies:

[0093] Different users have different scenarios and requirements. For game users who have high requirements for scene motion speed, it is preferred In office application scenarios, users have relatively low requirements for image quality, and the preferred For users who require a higher 3D experience,

[0094] The following case is an experimental test using the outermost lens mass of 80g as an example, as shown in the following table:

[0095]

[0096] Although the mass of the outermost lens in the above embodiment is 80g, the system can be considered to be scaled as a whole during design to obtain designs of other sizes and masses. This is very similar to the situation in fluid design. As long as the Reynolds numbers of the fluids are similar, the mathematical solutions will be very similar. Therefore, when a large model cannot be implemented, a small model with the same Reynolds number is usually used for experimental testing. In fact, we have also verified the above experimental scheme under the conditions of 50g, 20g, 10g, 5g, 2g, etc. The user experience feedback is consistent with the feedback results in the above table, which further proves the universality of the design formula.

[0097] In addition, a relatively rough but effective simplified design rule can be summarized from the above implementation feedback, namely: In some scenarios where the requirements are not too strict, a relatively complete product can also be obtained by simply simplifying the design rules.

[0098] It should be noted that the Bragg period scanning holographic imager of the present invention in which the projection display element serves as the two-dimensional imaging element 1 is used as a holographic projector, and the Bragg period scanning holographic imager of the present invention in which the photographing photosensitive element serves as the two-dimensional imaging element 1 is used as a holographic camera. The above design description is mainly explained for the case of a holographic projector. However, since the application of a holographic camera is very similar, based on the principle of reversible optical path, the problems that need to be considered for a holographic projector are also encountered by the holographic camera. Therefore, the above design description is also applicable to the holographic camera.

[0099] The two-dimensional imaging element 1 of the present invention can be configured to include both a projection display element and a photographing photosensitive element to achieve the dual functions of projection and photographing.

[0100] Usually, the depth resolution of the human eye is much lower than the lateral resolution, so even if the pixel pitch in the depth direction is larger, it will not cause resolution distortion. Therefore, the pixel pitch in the depth direction of the projection image can be set larger, so that a very realistic 3D image can be projected while effectively reducing equipment and process costs.

[0101] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A micro-scanning holographic imager, characterized in that: Including the following components respectively arranged inside the holographic imager: Two-dimensional imaging element (1); At least one galvanometer mirror (2), the position of which corresponds to the two-dimensional imaging element (1), and is used to optically transform light and form an equivalent image plane (3); An imaging lens group (4), whose position corresponds to the equivalent image plane (3) and is used to perform optical imaging on the light and form a two-dimensional picture (5); and The focal depth scanning mechanism (6) is connected to the galvanometer (2) and is used to control the spatial position change of the galvanometer (2) to achieve volume scanning of the two-dimensional image (5); wherein: The number of the galvanometers (2) is N, and the mass of any one of the galvanometers (2) is g, the amplitude is A mm, the mass of the outermost lens of the holographic imager is mg, and it satisfies: .

2. The micro-scanning holographic imager according to claim 1, characterized in that: The focal depth scanning mechanism (6) is also respectively connected to the two-dimensional imaging element (1) and / or the imaging lens group (4) and is used to control the spatial position change of the two-dimensional imaging element (1) and / or the imaging lens group (4) to achieve volume scanning of the two-dimensional picture (5).

3. The micro-scanning holographic imager according to claim 1, characterized in that: The focal depth scanning mechanism (6) is also connected to the imaging lens group (4) and is used to control the change of the effective focal length of the imaging lens group (4) to achieve volume scanning of the two-dimensional picture (5).

4. The micro-scanning holographic imager according to claim 3, characterized in that: The imaging lens group (4) comprises at least a liquid variable focus lens or a flexible variable focus lens.

5. The micro-scanning holographic imager according to any one of claims 1 to 4, characterized in that: The scanning frequency of the focal depth scanning mechanism (6) is greater than 6 Hz.

6. The micro-scanning holographic imager according to any one of claims 1 to 4, characterized in that: The two-dimensional imaging element (1) is a projection display element or a photographing photosensitive element.

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