CN111399332A - Micro-scanning holographic imager - Google Patents
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Abstract
The invention relates to the field of 3D imaging, and discloses a micro-scanning type holographic imager which comprises a two-dimensional imaging element, at least one vibrating mirror, an imaging lens group and a focal depth scanning mechanism, wherein the two-dimensional imaging element, the at least one vibrating mirror, the imaging lens group and the focal depth scanning mechanism are respectively arranged in the holographic imager; the position of the galvanometer corresponds to the two-dimensional display element and is used for optically converting light rays and forming an equivalent image surface; the position of the imaging lens group corresponds to the position of the two-dimensional imaging element, and the imaging lens group is used for optically converting light rays and forming a two-dimensional picture; the focal depth scanning mechanism is connected with the galvanometer and used for controlling the spatial position change of the galvanometer and realizing the volume scanning of two-dimensional pictures. The invention realizes the periodic volume scanning (Bragg periodic scanning) of a projection picture by introducing the focal depth scanning mechanism and the plurality of galvanometers, greatly reduces the amplitude of the volume scanning, improves the scanning frequency, and can stably realize the 3D imaging/projection display function of ultrahigh resolution and ultrafast frame frequency.
Description
Technical Field
The invention relates to the field of 3D imaging, in particular to a micro-scanning type holographic imager.
Background
The 3D display technology can provide additional depth information on the basis of the conventional two-dimensional display, and thus is considered to be a development direction of the next generation display technology. However, at present, no effective scheme for realizing 3D display exists, and most of the successful commercial cases are pseudo-3D technologies based on stereo image pairs, and cannot provide a true 3D picture with depth information for users. For example, in a 3D movie of a movie theater, the principle is to use a projector to project two-dimensional left and right eye image pairs on a screen, and to wear selective filter eyes, so that the two eyes receive different images, thereby giving people an illusion of seeing a 3D image, but the projected image is only a 2D image. Long-term viewing can also cause eye discomfort.
The true 3D effect can be realized by using a volume scanning imaging mode, and the method is a very potential 3D solution. However, the volume scanning imaging 3D usually requires a high-speed rotating/moving screen, the system has a large potential safety hazard, poor stability, very limited display space, no direct touch interaction, transparent display image path, and no expression of correct shielding relationship.
Patents entitled CN106773469B, CN 207114903U and CN 206431409U disclose a scheme that can implement true 3D display. The key component of the three-dimensional display device is a three-dimensional display module, and the three-dimensional display module can realize real 3D picture reproduction through depth-of-field scanning. The working principle is that one focal plane is scanned back and forth in the depth direction (depth of field scanning) to form a continuous 3D picture. Although the mode can realize the projection of the 3D picture, the requirement on the movement speed of a mechanical structural part of a display system is extremely high depending on the scanning imaging of a single focal plane, the reliability of the system cannot be ensured, the refreshing speed of the picture and the overall brightness of the picture cannot be optimized, meanwhile, an operation and control system is extremely complex, stable picture display is difficult to realize, and the manufacturing cost is extremely high. Thus, the reliability of the system is difficult to ensure, the anti-vibration capability of the imaging chip is very limited, even if damage is caused by common collision or falling, the position accuracy of the imaging lens is also difficult to stabilize, and the imaging quality is seriously influenced once the imaging lens deviates from an ideal assembling position.
An all-solid-state holographic projector, application No. 202010029144.5, achieves the effect of an all-solid-state holographic display by providing multiple discrete focal planes within a projector. However, the 3D picture formed in this way is not continuous, but one slice picture in real space cannot completely realize continuous 3D picture, and meanwhile, there are limited display space, failure to correctly express the occlusion relation, potential safety hazard, and poor system reliability. In addition, the problem that the device is heavy in application form and has large limitation exists.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the defects of the prior art, the micro-scanning type holographic imager is provided, the periodic volume scanning of an imaging picture is realized by introducing a focal depth scanning mechanism and a plurality of galvanometers, the amplitude of the volume scanning is greatly reduced, the scanning frequency is improved, and the 3D imaging/projection display function of ultrahigh resolution and ultrafast frame frequency can be stably realized.
In order to solve the above technical problems, the present invention provides a micro-scanning holographic imager, comprising:
a two-dimensional imaging element;
the position of the at least one galvanometer corresponds to the two-dimensional imaging element and is used for optically converting light rays and forming an equivalent image surface;
the imaging lens group corresponds to the equivalent image surface in position and is used for optically converting light rays and forming a two-dimensional picture; and
and the focal depth scanning mechanism is connected with the galvanometer and used for controlling the spatial position change of the galvanometer and realizing the volume scanning of the two-dimensional picture.
Furthermore, the focal depth scanning mechanism is also respectively connected with the two-dimensional imaging element and/or the imaging lens group, and is used for controlling the spatial position change of the two-dimensional imaging element and/or the imaging lens group, so as to realize the volume scanning of the two-dimensional image.
Furthermore, the focal depth scanning mechanism is also connected with the imaging lens group and used for controlling the change of the effective focal length of the imaging lens group to realize the volume scanning of the two-dimensional picture.
Further, the imaging lens group at least comprises a liquid zoom lens or a flexible zoom lens.
Further, the number of the galvanometers is N, and the mass of any galvanometer is MNg. The amplitude is A mm, the mass of the outermost lens of the holographic imager is mg, and the requirements are met:
further, the scanning frequency of the focal depth scanning mechanism is greater than 6 Hz.
Further, the two-dimensional imaging element is a projection display element or a photographing photosensitive element.
Compared with the prior art, the invention has the advantages that:
1. the invention replaces the high-speed large-range scanning equipment of the traditional volume scanning by micro scanning, the volume of the equipment is extremely small, the effective display space is extremely large, and the safety problem caused by high-speed moving parts is avoided;
2. the scanning component is packaged inside and is not contacted with the outside, so that the scanning component is not easy to damage;
3. when the invention is applied, the eyes need to dynamically adjust the focal depth as the eyes watch real objects, but not the fixed focal depth of the common 2D display picture, so that the visual fatigue can not be caused, and the invention is beneficial to protecting the eyesight;
4. the invention can realize the functions of projection and shooting at the same time, and is convenient for outputting the picture information and receiving the external image information in real time during practical application.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Figure 1 is a schematic diagram of an imager of the present invention in which the two-dimensional imaging element 1 is a projection display element and a system of embodiment 1,
FIG. 2 is a schematic diagram of the system of the imager of the present invention with the projection display element replaced by a photographic light-sensitive element, based on FIG. 1,
figure 3 is a schematic diagram of the system of example 2,
figure 4 is a schematic diagram of the system of example 3,
figure 5 is a schematic diagram of the system of example 4,
fig. 6 is a state diagram of one vibration cycle of the equivalent image plane 3,
FIG. 7 is a schematic diagram of the mechanical zooming of the imaging lens assembly 4,
FIG. 8 is a schematic view of the zooming principle of the imaging lens assembly 4 using a flexible zoom lens,
FIG. 9 is a schematic diagram showing the relationship between the amplitudes of the galvanometer 2 and the two-dimensional imaging element 1 when the two-dimensional imaging element is at an angle of 45 degrees,
fig. 10 is a system diagram of the imager of the present invention when the number of galvanometers 2 is 2,
the reference numbers are as follows:
the device comprises a two-dimensional imaging element 1, a galvanometer 2, an equivalent image surface 3, an imaging lens group 4, a two-dimensional picture 5 and a focal depth scanning mechanism 6.
Detailed Description
The following detailed description of the present invention is given for the purpose of better understanding technical solutions of the present invention by those skilled in the art, and the present description is only exemplary and explanatory and should not be construed as limiting the scope of the present invention in any way.
Referring to fig. 1 to 10, the present invention provides a micro-scanning holographic imager, which includes a two-dimensional imaging element 1, at least one galvanometer 2, an imaging lens group 4 and a focal depth scanning mechanism 6 respectively disposed therein;
the position of the galvanometer 2 corresponds to the two-dimensional imaging element 1 and is used for optically converting light rays and forming an equivalent image surface 3;
the position of the imaging lens group 4 corresponds to the equivalent image surface 3, and the imaging lens group is used for optically converting light rays and forming a two-dimensional picture 5;
the focal depth scanning mechanism 6 is connected with the galvanometer 2 and is used for controlling the spatial position change of the galvanometer 2 and realizing the volume scanning of the two-dimensional picture 5;
the two-dimensional imaging element 1 of the present invention may be a projection display element or a photographing photosensitive element:
as shown in fig. 1, when the two-dimensional imaging device 1 is a projection display device, the projection light of the projection display device is optically transformed by the galvanometer 2 and the imaging lens group 4 in sequence to project a two-dimensional image 5 in space, which is equivalent to the imaging effect of an equivalent image plane 3 projected by the imaging lens group 4, the focal depth scanning mechanism 6 controls the galvanometer 2 to vibrate, so that the relative position between the equivalent image plane 3 and the imaging lens group 4 changes, and the two-dimensional image 5 vibrates in the focal depth direction, thereby realizing the volume scanning of the two-dimensional image 5, and finally achieving the 3D display effect, wherein the two-dimensional image 5 and the equivalent image plane 3 have an optical conjugate relationship, therefore, when the two-dimensional picture 5 is subjected to volume scanning, the equivalent image plane 3 is also subjected to volume scanning at the same time, the two-dimensional picture 5 is an optically transformed real image plane, and the equivalent image plane 3 is a virtual image plane obtained through optical transformation;
as shown in fig. 2, when the two-dimensional imaging element 1 is a photographing photosensitive element, the optical path is reversible, light of an external scene is sequentially optically converted by the imaging lens group 4 and the galvanometer 2, a two-dimensional image 5 of a real image is generated on the photographing photosensitive element and recorded, and light equivalent to the external scene is optically converted by the imaging lens group 4 to directly generate an imaging effect equivalent to an image plane 3;
however, only the scenery in the optical conjugate depth of field with the shooting photosensitive element or the equivalent image plane 3 can be clearly recorded in the imaging process, and the scenery with other depth of field can not realize clear imaging recording. When the focal depth scanning mechanism 6 controls the vibration of the galvanometer 2, the relative position of the galvanometer 2 and the imaging photosensitive element changes, the spatial position relationship between the equivalent image plane 3 and the imaging lens group 4 changes periodically (micro-scanning), and the depth of field optically conjugated with the imaging photosensitive element or the equivalent image plane 3 changes periodically, so as to achieve the purpose of depth of field scanning, so that the scenes in different depths of field are imaged and recorded respectively, 3D shooting is realized, the equivalent image plane 3 also has corresponding periodic scanning according to the process of periodic scanning of the depth of field space optically conjugated with the imaging photosensitive chip or the equivalent image plane 3 according to the reversible optical path, and the equivalent image plane 3 and the two-dimensional image 5 have the equivalent relationship, so that the scanning of the equivalent image plane 2 can be equivalent to the scanning of the two-dimensional image 5, the two-dimensional image 5 is an optically transformed real image plane, the equivalent image surface 3 is a virtual image surface obtained through optical conversion;
the volume scanning is also equivalent to the depth scanning of a 3D picture, and an imaging space can be scanned, thereby realizing the effect of 3D display.
Because the projected two-dimensional picture 5 and the shot two-dimensional picture 5 are fully distributed with pixel arrays (two-dimensional), after the volume scanning, a three-dimensional pixel array can be formed. For example, the movement range of the equivalent image plane 3 is the equivalent scanning range (i.e. the area of the equivalent image plane 3 is multiplied by 2 times of the scanning amplitude in the vertical direction, which can be denoted as V)Equivalence of) The actual scanning range is the moving range of the galvanometer 2 (i.e. the area of the galvanometer 2 is multiplied by 2 times of the scanning amplitude in the vertical direction, and can be recorded as VScanning) The ratio of the two is preferably set to be greater than 1.2 (a specific magnification setting mode can be realized through an optical geometric relationship, which is not described herein), 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, so as to further enlarge the imaging space to be greater than 53And (4) doubling.
Another advantage of such a scanning system is that critical components such as the two-dimensional imaging element 1 and the imaging mirror group 4 can be in a completely stationary state or in a very slightly moving state, thereby making the system more reliable.
The invention controls the space position change of the galvanometer 2 through the arranged focal depth scanning mechanism 6, preferably periodically changes, realizes the volume scanning of the two-dimensional picture 5, and preferably realizes the volume scanning by reciprocating the two-dimensional picture 5 back and forth. For example, the galvanometer 2 is periodically scanned in a reciprocating manner in a space by a mechanical manner, that is, a continuous space can be scanned in the space, in practical application, the galvanometer can be scanned in a reciprocating manner at a fixed frequency, and different frequencies can be used for scanning according to the requirement of display content; the design of the scanning mechanism belongs to the common knowledge in the art, and the specific implementation manner can be designed according to the actual situation, which is not described herein.
The periodic variation of the effective focal length of the imaging lens group 4 can be further controlled by the focal depth scanning mechanism 6, and the volume scanning of the two-dimensional picture 5 can also be realized, the periodic variation of the effective focal length of the imaging lens group 4 can be realized by changing the relative position and/or the overall position of the optical elements in the imaging lens group 4 (mechanical zooming), and a liquid zoom lens and/or a flexible zoom lens with a zooming function can also be arranged in the imaging lens group 4;
further, the focal depth scanning mechanism 6 may be further connected to the two-dimensional imaging element 1 and/or the imaging lens group 4, respectively, and is configured to control spatial position variation of the two-dimensional imaging element 1 and/or the imaging lens group 4, so as to implement volume scanning of the two-dimensional image 5, and also implement the above-mentioned 3D imaging effect.
In addition, the display effect can be further improved by a three-dimensional scanning mode besides the pure one-dimensional depth-of-field scanning. For example, the scanning parallel to the equivalent image plane is added, so that the lateral resolution can be further increased, and the image quality is more exquisite.
The invention will be further described below by taking a two-dimensional imaging element 1 as a projection display element and a micro-scanning holographic imager comprising only one galvanometer 2 as an example:
example 1
As shown in fig. 1, the micro-scanning holographic imager includes a projection display element, a vibrating mirror 2, an imaging lens group 4 and a focal depth scanning mechanism 6, which are respectively disposed inside the micro-scanning holographic imager, the focal depth scanning mechanism 6 is connected to the vibrating mirror 2 and controls the front-back reciprocating scanning (or periodic variation) of the spatial position of the vibrating mirror 2, so that the relative position between the equivalent image plane 3 formed by optical transformation of the vibrating mirror 2 and the imaging lens group 4 is periodically varied, and the position of the two-dimensional image 5 conjugated to the equivalent image plane 3 is also periodically varied along the focal depth direction, thereby realizing the front-back reciprocating scanning of the two-dimensional image 5 and presenting the 3D display effect.
Example 2
As shown in fig. 3, the micro-scanning holographic imager includes a projection display element, a vibrating mirror 2, an imaging mirror group 4 and a focal depth scanning mechanism 6, which are respectively disposed inside, the focal depth scanning mechanism 6 is respectively connected to the projection display element and the vibrating mirror 2 and controls the periodic variation of the spatial positions of the projection display element and the vibrating mirror 2, so that the relative position between the equivalent image plane 3 formed by optical transformation of the vibrating mirror 2 and the imaging mirror group 4 is periodically varied, and the position of the two-dimensional image 5 conjugated to the equivalent image plane 3 is periodically varied along the focal depth direction, thereby realizing the back-and-forth scanning of the two-dimensional image 5 and presenting the 3D display effect.
Example 3
As shown in fig. 4, the micro-scanning holographic imager includes a projection display element, a vibrating mirror 2, an imaging lens group 4 and a focal depth scanning mechanism 6, which are respectively disposed inside the micro-scanning holographic imager, the focal depth scanning mechanism 6 is respectively connected to the vibrating mirror 2 and the imaging lens group 4 and controls the periodic variation of the spatial positions of the vibrating mirror 2 and the imaging lens group 4, so that the relative position between the equivalent image plane 3 formed by optical transformation of the vibrating mirror 2 and the imaging lens group 4 is periodically varied, and the position of the two-dimensional image 5 conjugated to the equivalent image plane 3 is periodically varied along the focal depth direction, thereby realizing the back-and-forth scanning of the two-dimensional image 5 and presenting the 3D display effect.
Example 4
As shown in fig. 5, the micro-scanning holographic imager includes a projection display element, a vibrating mirror 2, an imaging lens group 4 and a focal depth scanning mechanism 6, which are respectively disposed inside, the focal depth scanning mechanism 6 is respectively connected to the projection display element, the vibrating mirror 2 and the imaging lens group 4 and controls the periodic variation 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 vibrating mirror 2 and the imaging lens group 4 is periodically varied, and the position of the two-dimensional image 5 conjugated to the equivalent image plane 3 is also periodically varied along the focal depth direction, thereby realizing the back-and-forth reciprocating scanning of the two-dimensional image 5 and presenting the 3D display effect.
Example 5
The micro-scanning type holographic imager comprises a projection display element, a vibrating mirror 2, an imaging mirror group 4 and a focal depth scanning mechanism 6 which are arranged inside the micro-scanning type holographic imager respectively, wherein the focal depth scanning mechanism 6 is connected with the vibrating mirror 2 and the imaging mirror group 4 respectively and controls the spatial position of the vibrating mirror 2 and the effective focal depth of the imaging mirror group 4 to change periodically, so that the relative position between an equivalent image surface 3 formed by optical transformation of the vibrating mirror 2 and the imaging mirror group 4 changes periodically, and the position of a two-dimensional picture 5 conjugated with the equivalent image surface 3 also changes periodically along the focal depth direction, thereby realizing the front-back reciprocating scanning of the two-dimensional picture 5 and presenting the 3D display effect.
In embodiment 5, the focal depth scanning mechanism 6 can control the effective focal depth of the imaging lens group 4 by:
as shown in fig. 7, the focal depth scanning mechanism 6 controls the relative position and/or the overall position of a plurality of optical elements arranged in the imaging lens group 4 to change (mechanical zooming), so as to control the periodic change of the effective focal length of the imaging lens group 4;
as shown in fig. 8, a flexible zoom lens with a zoom function may be further disposed in the imaging lens group 4, and the focal length of the flexible zoom lens is controlled by the focal depth scanning mechanism 6 to realize the control of the periodic variation of the effective focal length of the imaging lens group 4, and the flexible zoom lens may also be replaced by other lenses with a zoom function, such as a liquid zoom lens;
of course, the imaging lens group 4 in embodiments 3 and 4 may also have a zoom function, and the focal depth scanning mechanism 6 is used to perform uniform control to achieve back-and-forth reciprocating scanning of the two-dimensional image 5, and in addition, the number of the galvanometers 2 may also be multiple, as shown in fig. 9, where the number of the galvanometers 2 is 2.
The projection display devices of embodiments 1-5 can be replaced by photographic sensitive devices according to the principle of reversible optical path, as shown in fig. 2, to achieve the effect of 3D photography.
As shown in fig. 6, in practical application, when the focal depth scanning mechanism 6 operates to realize volume scanning on the two-dimensional picture 5, the equivalent image plane 3 optically conjugate with the two-dimensional picture 5 also performs volume scanning at the same time;
the vibration controlled by the focal depth scanning mechanism 6 and the scanning of the equivalent image plane 3 are in a linear corresponding relationship, and based on the lens imaging rule, the scanning of the two-dimensional picture 5 in the focal depth direction and the scanning of the equivalent image plane 3 are not in a linear corresponding relationship, so that the design of related design parameters by taking the equivalent image plane 3 as a reference is more convenient:
the amplitude of the equivalent image plane 3 in the depth-of-focus direction (i.e., the maximum displacement of the equivalent image plane 3 from the equilibrium position in the depth-of-focus direction) is L mm, the equilibrium position of the equivalent image plane 3 is the midpoint between two points, namely the depth-of-focus direction amplitude point and the depth-of-focus direction amplitude point, of the equivalent image plane 3, and the amplitude point of the equivalent image plane 3 is as shown in fig. 6, where the maximum displacement of the equivalent image plane 3 in the depth-of-focus direction is defined as the depth-of-focus direction amplitude point and the maximum displacement in the depth-of-focus direction is defined as the depth-;
because of the existence of the galvanometer 2, the amplitude L of the equivalent image plane 3 optically transformed by the galvanometer 2 should have a geometric correspondence with the amplitude in the vertical direction of the galvanometer 2, and the amplitude in the vertical direction of the galvanometer 2 is a mm, it should be noted that the amplitude a in the vertical direction of the galvanometer 2 should be interpreted as the maximum displacement of the galvanometer 2 deviating from the equilibrium position of the galvanometer 2 in the direction vertical to the amplitude a in the vertical direction during the vibration process, and the equilibrium position of the galvanometer 2 is the midpoint position of the maximum displacement in the positive and negative directions of the vibration of the galvanometer 2;
the amplitude of the vertical direction of the galvanometer 2 is a mm, which is associated with the angle between the galvanometer 2 and the two-dimensional imaging element 1, and the following description will take an example in which the angle between the galvanometer 2 and the two-dimensional imaging element 1 is 45 degrees:
as shown in fig. 9, the number of galvanometers 2 is 1, the amplitude is a mm, and the amplitude L of the volume scan of the equivalent image plane 3 is
Vibrating mirror2 are arranged in parallel with each other, the frequencies are the same, and the amplitudes are all a mm, so that the amplitude L of the volume scan of the equivalent image plane 3 is equal to
When the number of the galvanometers 2 is 3 and the galvanometers are arranged in parallel with each other, the frequencies are the same, and the amplitudes are all a mm, the amplitude L of the volume scanning of the equivalent image plane 3 is
By analogy, if the number of the galvanometers 2 is N, the galvanometers are arranged in parallel, the frequencies are the same, and the amplitudes are all a mm, the amplitude L of the volume scanning of the equivalent image plane 3 is equal to
In practical application, when a plurality of galvanometers 2 are arranged in a non-parallel manner, the amplitude L of the equivalent image surface 3 along the focal depth direction can be obtained finally according to geometric operation;
in practical application, the volume scanning amplitude can be made larger or smaller for scenes with low pursuit of depth resolution in order to show a finer picture effect.
In practical application, the scanning frequency or equivalent frequency of the focal depth scanning mechanism 6 is preferably greater than 6 Hz;
the frequency here refers to the reciprocal of a time interval between two consecutive passes of a certain spatial point in the same moving direction of the moving part, for example, the reciprocal of a time interval between two consecutive passes of the equilibrium position of the galvanometer 2 in the same scanning direction in the reciprocating scanning process of the galvanometer 2, and the equilibrium position of the galvanometer 2 here has been explained above and is not described again here;
in addition, there is a special case, that is, when the display space has overall motion, such as the process of moving from a close view to a far view, the depth of field in the switching process usually only needs to move in a single direction without reciprocating scanning, and then there is no concept of depth of field scanning, but the display depth of field switching process also needs to be completed in a relatively proper speed, otherwise, the picture is easy to jump or smear, for this case, we introduce the concept of equivalent frequency, that is, the equivalent frequency is the reciprocal of the time used in the process that the moving distance is equal to the amplitude L of the equivalent image plane 3 when the equivalent image plane 3 makes single-direction motion relative to the imaging lens group 4;
for the case of performing the scanning in the zooming manner, the reciprocal of the time from the initial focal length to the focal length again (or the reciprocal of the time interval from the maximum focal length to the maximum focal length again) in the equivalent focal length variation process may be adopted, 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 operating. Of course, it is also possible to measure the inverse of the time interval during which the projected focal plane is swept twice in succession over a certain position in space in the same direction.
When a 3D picture is displayed in a certain space, the focal plane needs to scan back and forth in the certain space to complete the update of the full-space picture, so the frame frequency of the 3D picture is the depth-of-field scanning frequency.
The frame frequency of each second during imaging depends on the scanning frequency, in the actual display process, when the frame frequency is more than 12, a continuous picture can be formed by using the persistence of vision principle of human eyes, in addition, under some special occasions, some blocking picture effects need to be created, so that the purpose can be achieved by taking half of the continuous frame frequency, and therefore, the scanning frequency of the focal depth scanning mechanism 6 is preferably more than 6 Hz.
In addition, in order to pursue an optimal overall display effect, each component needs to be finely designed.
On the one hand, the large viewing angle display capability needs to be improved, so that the area of the galvanometer 2 is as large as possible, and the effective optical area of the lens can be better utilized. On the other hand, it is also necessary to ensure excellent depth-of-field detail representation capability as much as possible, that is, to increase the volume scanning frequency, and for a mechanical scanning system, the optimal configuration for scanning is to use its natural frequency for scanning, and there is usually a negative correlation between the natural frequency of the mechanical system and the mass of the vibrating component. The mass of the lens needs to be smaller and the corresponding area will be smaller. In addition, for a product, it is also very important to improve the stability of the system, the smaller the amplitude of vibration in the scanning process is, the closer the system is to the solid state, the better the stability is, but the amplitude is too small, the field depth expression range is restricted, and the expression of the ultra-large field depth is difficult to complete. In addition, if the mass and amplitude of the moving part are both large, the backlash effect on the system is obvious, and the situation of picture jitter and the like is easy to occur.
In summary, for such a new scheme, three mutually opposite indexes, namely, the effective optical utilization area, the scanning frequency, and the scanning amplitude, need to be considered at the same time, and the three indexes cannot achieve the optimal design at the same time, and a certain balance and optimization are needed to obtain a relatively excellent comprehensive performance.
Since there has not been any appreciable design experience, it is difficult to actually design a product with superior performance, although the imaging principles are relatively well understood. The present invention therefore provides an easy to implement design-guiding rule to help practitioners in the art design products with superior performance.
Generally, for a specific lens imaging application scene, the thickness range of the main lens is very narrow, such as a single lens reflex, the thickness (central thickness) of the outermost lens is generally between 1 mm and 5mm, and the range is narrower without considering some extreme special cases in practical situations, which is mainly limited by the design rule of the imaging lens. Therefore, the quality of the imaging lens is often largely dependent on the size of its aperture. In order to match the imaging lens, the area of the galvanometer 2 needs to be within a suitable range. In addition, the problem of mirror surface deformation caused by vibration in the scanning process, namely the problem of rigidity of the mirror plate, needs to be considered, namely, the thickness of the galvanometer 2 with a specific area needs to be designed to ensure that the rigidity is sufficient, so that the volume of the galvanometer is determined within a very small range, and the material density difference of the mirror plate is usually small, so that the mass of the galvanometer can be further determined within a reasonable range.
The performance of each aspect is balanced through the theoretical analysis, and the method is determined before a certain visual angle is ensured by combining experimental assembly testUnder the premise of better representing the parameter design space of the depth of field detail effect (because the design of the system mainly aims at the field of 3D imaging, the depth of field representation capability needs to be preferentially ensured in the design process), the mass of any one galvanometer 2 is MNg. The amplitude is A mm, the mass of the outermost lens of the holographic imager is mg, and the requirements are as follows:
in the case of using a plurality of galvanometers 2, the mass of the scanning mirror closest to the outermost mirror of the imaging lens is defined as M1g, the mass of other scanning lenses is defined as M2g、M3g、M4g……Mng, and satisfies:
the scene of the demand is different for different users, and the requirements are different. For the game user with higher requirement on scene motion speed, preference is given
In an office application scene, the requirements of users on image quality are relatively low, and the preference is high
While for users with a higher requirement for a 3D experience, preference is given to
The following cases were tested experimentally using an outermost lens mass of 80g, as specified in the following table:
although the mass of the outermost lens is 80g in the above embodiment, the design can be considered to scale the system as a whole, so that designs of other sizes and masses can be obtained, which is very similar to the case of fluid design, and the mathematical solutions of the fluid are very similar as long as the reynolds numbers of the fluid are similar, so that the experimental test is usually performed by using a small model with the same reynolds number in the case that a large model cannot be realized. In fact, in the above experimental scheme, we also verified under the conditions of 50g, 20g, 10g, 5g, 2g, etc., the user experience feedback is consistent with the feedback result in the table, and the generality of the design formula is further proved.
Furthermore, a relatively coarse but also effective simplified design rule can be concluded from the above implementation feedback, i.e.
Under the condition of less strict requirements, the relatively perfect product can be obtained by directly simplifying the design rule.
It should be noted that the bragg period scanning type hologram imager of the present invention in which the projection display element is the two-dimensional imaging element 1 is used as a hologram projector, and the bragg period scanning type hologram imager of the present invention in which the photographing photosensitive element is the two-dimensional imaging element 1 is used as a hologram recorder, and the above description of the design is mainly explained for the case of the hologram projector, but since the application of the hologram recorder is very similar, the problem that the hologram projector needs to consider based on the principle of reversible optical path is also encountered in the hologram recorder, and therefore the above description of the design is also applicable to the hologram recorder.
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 realize dual functions of projection and photographing.
Generally, the depth resolution of human eyes is far lower than the lateral resolution, so that resolution distortion cannot be caused even if the pixel pitch in the depth direction is large, and therefore the pixel pitch of a projection picture in the depth direction can be set to be larger, so that a very real 3D picture can be projected under the condition of effectively reducing equipment and process cost.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (7)
1. Micro-scanning formula holographic imager, its characterized in that is including setting up respectively in holographic imager inside:
a two-dimensional imaging element (1);
at least one galvanometer (2) which is positioned corresponding to the two-dimensional imaging element (1) and is used for optically converting light rays and forming an equivalent image surface (3);
the imaging lens group (4) corresponds to the equivalent image surface (3) in position, is used for optically imaging light rays and forms a two-dimensional picture (5); and
and the focal depth scanning mechanism (6) is connected with the galvanometer (2) and is used for controlling the spatial position change of the galvanometer (2) and realizing the volume scanning of the two-dimensional picture (5).
2. The micro-scanning holographic imager of claim 1, wherein: the focal depth scanning mechanism (6) is also respectively connected with the two-dimensional imaging element (1) and/or the imaging lens group (4) and is used for controlling the spatial position change of the two-dimensional imaging element (1) and/or the imaging lens group (4) and realizing the volume scanning of the two-dimensional picture (5).
3. The micro-scanning holographic imager of claim 1, wherein: the focal depth scanning mechanism (6) is also connected with the imaging lens group (4) and is used for controlling the change of the effective focal length of the imaging lens group (4) and realizing the volume scanning of the two-dimensional picture (5).
4. A micro-scanning holographic imager in accordance with claim 3, wherein: the imaging lens group (4) at least comprises a liquid zoom lens or a flexible zoom lens.
5. The micro-scanning holographic imager of claim 1, wherein: the number of the vibrating mirrors (2) is N, and the mass of any one vibrating mirror (2) is MNg. The amplitude is A mm, the mass of the outermost lens of the holographic imager is mg, and the requirements are met:
6. a micro-scanning holographic imager as claimed in any one of claims 1 to 5, wherein: the scanning frequency of the focal depth scanning mechanism (6) is more than 6 Hz.
7. A micro-scanning holographic imager as claimed in any one of claims 1 to 5, wherein: the two-dimensional imaging element (1) is a projection display element or a shooting photosensitive element.
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| CN202010401923.3A CN111399332A (en) | 2020-05-13 | 2020-05-13 | Micro-scanning holographic imager |
| PCT/CN2021/093251 WO2021228120A1 (en) | 2020-05-13 | 2021-05-12 | Scanning-type holographic imaging device and related system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2021228120A1 (en) * | 2020-05-13 | 2021-11-18 | 荆门市探梦科技有限公司 | Scanning-type holographic imaging device and related system |
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