CN112433386A - Compact optical structure for light field display - Google Patents
Compact optical structure for light field display Download PDFInfo
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- CN112433386A CN112433386A CN201910734430.9A CN201910734430A CN112433386A CN 112433386 A CN112433386 A CN 112433386A CN 201910734430 A CN201910734430 A CN 201910734430A CN 112433386 A CN112433386 A CN 112433386A
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- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/01—Head-up displays
- G02B27/017—Head mounted
- G02B27/0172—Head mounted characterised by optical features
Abstract
The invention discloses a compact optical structure for light field display, comprising an imaging assembly, the imaging assembly comprising: the polarization beam splitter completely reflects the incident beam with the polarization state of S state and completely transmits the incident beam with the polarization state of P state; the display screen consists of M sub-screens, and light information emitted by each sub-screen is respectively incident to the polarized light spectroscope; two wave plates for changing the polarization state of the incident light beam; two reflection modulation devices for phase modulating light; the compact optical structure further comprises: the device comprises a small-space aperture array, a control unit and a diaphragm. The invention relates to a compact optical structure for light field display, which designs a compact optical structure capable of realizing monocular multi-view presentation by means of the regulation and control of a polarized light spectroscope and a wave plate on a polarized light state, so that the three-dimensional visual comfort level is improved through three-dimensional display capable of naturally focusing. The compact optical structure can be used as an eyepiece of the head-mounted VR/AR alone.
Description
Technical Field
The invention relates to the technical field of three-dimensional display, in particular to a compact optical structure for light field display.
Background
The existing three-dimensional display system based on the stereoscopic technology is based on different views respectively received by each eye, and the three-dimensional depth perception is constructed by converging different spatial positions in a binocular visual direction. However, in order to clearly see the respective views of the two eyes, the viewer needs to focus his/her eyes on the display surface. The focusing-converging conflict generated by the method is inconsistent with the natural physiological response of human eyes when the real three-dimensional space scenery is observed, and is the main reason for the visual fatigue generated during the three-dimensional film watching.
PCT15/481,467 (this-temporal DISPLAY SYSTEM BASED ON visual multi-level OF THE VIEWER 'S ENTRANCE-PUPIL AND DISPLAY METHOD thermal) discloses a light field display technique to overcome focus-convergence conflicts by projecting different views through different regions OF the observer's PUPIL and using the corresponding eyes to receive spatial superposition OF the different view emergent rays to form a true spatial spot that can be naturally focused by the monocular to overcome the focus-convergence conflict. However, in the head-mounted near-eye display system disclosed in the above patent, the focal length of the projection lens is larger, resulting in a larger size of the optical structure.
Disclosure of Invention
In order to overcome the drawbacks of the background art, i.e. to reduce the size of the optical structure while overcoming the light field display of focus-convergence conflicts, the present invention provides the following solutions:
a compact optical structure for light field display comprising an imaging assembly comprising:
the polarization beam splitter completely reflects the incident beam with the polarization state of S state and completely transmits the incident beam with the polarization state of P state;
the display screen is arranged at a position corresponding to the polarizing beam splitter, so that light information emitted by each sub-screen is incident to the polarizing beam splitter respectively, the polarization state of emergent light of adjacent sub-screens is one of S state and P state respectively, and the polarization states of emergent light of adjacent sub-screens are different from each other, wherein M is not less than 2;
the two wave plates are respectively arranged in front of the polarization beam splitter along the transmission light transmission direction and the reflection light transmission direction of the polarization beam splitter and are used for changing the polarization state of an incident light beam, so that the P-state light beam passing through the wave plates twice is changed into an S-state light beam, and the S-state light beam passing through the wave plates twice is changed into a P-state light beam;
the two reflection modulation devices are used for carrying out phase modulation on light, correspond to the two wave plates respectively, reflect light beams incident through the corresponding wave plates respectively, enable the light beams to enter the corresponding wave plates for the second time in a reverse direction, and then enter the polarization beam splitter again, and the two reflection modulation devices are respectively formed into amplified virtual images of each S-state sub-screen and each P-state sub-screen;
the imaging assembly is set to be capable of projecting M sub-screen virtual images arranged in the + x direction to the + z direction, and display screen virtual images formed by the M sub-screen virtual images are transmitted along the-z direction; the polarized light states of the equivalent emergent light of the adjacent sub-screen virtual images are respectively one of an S state and a P state, and the polarized light states of the equivalent emergent light of the adjacent sub-screen virtual images are different from each other;
the compact optical structure further comprises:
the small-space aperture array is composed of M multiplied by N apertures, the adjacent spacing of the apertures is smaller than the diameter Dp of the pupil of an observer in the + x direction, the apertures are arranged in front of the imaging assembly in the-z direction, M apertures spaced by N-1 apertures are respectively grouped, N aperture groups are staggered in the x direction, one aperture is staggered in the x direction, M apertures and M sub-screen virtual images in each aperture group correspond to one another in sequence in the + x direction, the polarization state of light passing through each aperture when the aperture is opened is consistent with the equivalent emergent polarization state of the corresponding sub-screen virtual image, and N is not less than 2;
the control unit controls the N aperture groups to be opened in sequence only by one group at each N adjacent time points, and controls the display screen to synchronously project a view of a scene to be displayed relative to the opened aperture group;
the display screen projects a view of a scene to be displayed relative to a corresponding open aperture group, the view projection area is a virtual image coverage area of each sub-screen of the display screen, and a viewpoint is an intersection point of straight lines which respectively pass through each virtual image area of the sub-screen and a corresponding aperture of the virtual image of the sub-screen in the open aperture group;
and the diaphragm is arranged at the small-spacing aperture array and used for blocking the transmission part of emergent light from the display screen in the area except the small-spacing apertures.
Above-mentioned scheme is through selecting for use the different display screens of different regional emergent light polarization states to the polarisation spectroscope combines reflective phase modulation device and wave plate as light beam splitting and light fusion device, utilizes reflective phase modulation device easily to realize the characteristic of short focus lens, and the turning back of optical path, designs a compact optical structure, through the time sequence on-off control of booth apart from the aperture array, realizes the light field display based on the monocular multiview, can regard as monocular eyepiece structure, builds wear-type VR, AR system.
Preferably, the imaging component further comprises an auxiliary modulation device, which is composed of at least one phase modulation device, is arranged on the transmission path of the emergent light beam of the display screen, and is matched with the two reflection modulation devices to form the amplified virtual images of each S-state sub-screen and each P-state sub-screen respectively. The auxiliary modulation device is combined with the two reflection modulation devices respectively to serve as equivalent imaging lenses to image each sub-screen of the display screen, so that the imaging quality of the single reflection modulation device to each corresponding sub-screen is improved, the focal length of the equivalent lens for imaging each sub-screen of the display screen is further shortened, and the optical structure is further facilitated to be compact.
Preferably, the corresponding N apertures of the same virtual sub-screen image in the N aperture groups are switchable, and the opening timing of the N aperture groups is switchable.
Preferably, the display screen projects a view of a scene to be displayed about a corresponding open aperture group, the view projection area is a virtual sub-screen image coverage area of the display screen, and the viewpoint is an intersection point of a virtual sub-screen image center and a connecting line of the virtual sub-screen image and the corresponding aperture center in the open aperture group.
Preferably, the compact optical structure further comprises a deflection device for deflecting the light beam passing through the small pitch aperture array and directing it to the observer pupil; the deflection device allows light from the external environment to be transmitted into the observer's pupil.
The invention also provides another scheme.
A compact optical structure for light field display comprising an imaging assembly comprising:
the polarization beam splitter completely reflects the incident beam with the polarization state of S state and completely transmits the incident beam with the polarization state of P state;
the display screen is arranged at a position corresponding to the polarizing beam splitter, so that light information emitted by each sub-screen is incident to the polarizing beam splitter respectively, the polarization state of emergent light of adjacent sub-screens is one of S state and P state respectively, and the polarization states of emergent light of adjacent sub-screens are different from each other, wherein M is not less than 2;
the two wave plates are respectively arranged in front of the polarization beam splitter along the transmission light transmission direction and the reflection light transmission direction of the polarization beam splitter and are used for changing the polarization state of incident light, so that the P-state light beams passing through the wave plates twice are changed into S-state light beams, and the S-state light beams passing through the wave plates twice are changed into P-state light beams;
the two reflection modulation devices are used for carrying out phase modulation on light, correspond to the two wave plates respectively, reflect the light beams incident through the corresponding wave plates respectively, enable the light beams to be incident into the corresponding wave plates for twice in a reverse direction, and then enter the polarization beam splitter again; the two reflection modulation devices are respectively formed into amplified virtual images of each S-state sub-screen and each P-state sub-screen;
the imaging assembly is set to be capable of projecting M sub-screen virtual images arranged in the + x direction to the + z direction, and display screen virtual images formed by the M sub-screen virtual images are transmitted along the-z direction; the polarized light states of the equivalent emergent light of the adjacent sub-screen virtual images are respectively one of an S state and a P state, and the polarized light states of the equivalent emergent light of the adjacent sub-screen virtual images are different from each other;
the compact optical structure further comprises:
the small-space aperture array is composed of M multiplied by N apertures, the adjacent spacing of the apertures is smaller than the diameter Dp of the pupil of an observer along the + x direction, the apertures are arranged in front of the imaging assembly along the-z direction, M apertures spaced by N-1 apertures are respectively grouped, N aperture groups in a group are staggered one aperture by one aperture along the + x direction, and along the + x direction, M apertures and M sub-screen virtual images in each aperture group correspond one by one in sequence, the polarization state of light allowed to pass through when each aperture is opened is consistent with the equivalent polarization state of the corresponding sub-screen virtual images, wherein N is not less than 2;
in each aperture group, starting from a first aperture along the + x direction, two adjacent apertures with different polarization states form a first aperture pair, then in the aperture group, starting from the first aperture behind the first aperture pair, defining a second aperture pair by the same method, repeating the steps, and determining all the aperture pairs in the aperture group, wherein when M is an odd number, the last aperture of the drop list is independently used as an aperture pair;
the control unit is used for opening only one aperture cluster in V aperture clusters formed by aperture pairs which are sequentially spaced by V-1 aperture pairs in one aperture group at a time point, and controlling N multiplied by V different aperture clusters of all the aperture groups to be opened sequentially at N multiplied by V time points which are adjacent within each time period delta t, wherein 2 is less than or equal to V less than or equal to [ (N +1)/2], [ ] is an integer symbol;
when only one aperture is opened, controlling the corresponding sub-screen to load information;
the loading information of the sub-screen corresponding to one aperture is information of a view of an aperture group to which the aperture belongs in a virtual image area of the display screen on a virtual image corresponding to the sub-screen;
the view of the display screen virtual image area relative to one aperture group, wherein the viewpoint of the view is the intersection point of straight lines which respectively pass through each sub-screen virtual image area and the corresponding aperture of the sub-screen virtual image area in the aperture group;
and the diaphragm is arranged at the small-spacing aperture array and used for blocking the transmission part of emergent light from the display screen in the area except the small-spacing apertures.
Preferably, the imaging component further comprises an auxiliary modulation device, which is composed of at least one phase modulation device, is arranged on the transmission path of the emergent light beam of the display screen, and is matched with the two reflection modulation devices to form the amplified virtual images of each S-state sub-screen and each P-state sub-screen respectively.
Preferably, the corresponding N apertures of the same virtual sub-screen image in the N aperture groups are switchable, and the opening timing of the N aperture groups is switchable.
Preferably, the viewpoint of the view of the display screen virtual image region about one aperture group is the intersection point of the center of each sub-screen virtual image and the connecting line of the corresponding aperture centers of the sub-screen virtual images in the aperture group.
Preferably, the compact optical structure further comprises a deflection device for deflecting the light beam passing through the small pitch aperture array and directing it to the observer pupil; the deflection device allows light from the external environment to be transmitted into the observer's pupil.
The invention has the following technical effects: according to the compact optical structure for light field display, the display screens with different emergent light polarization states in different areas are selected, the polarization spectroscope is used as a light beam splitting and light fusion device, the reflective phase modulation device and the wave plate are combined, the characteristic that the reflective phase modulation device is easy to realize a short-focus lens and the turning back of an optical path are utilized, the compact optical structure is designed, the light field display is realized based on monocular multiview through the time sequence switch control of a small-distance aperture array, and the compact optical structure can be used as a monocular eyepiece structure to build a head-mounted VR and AR system. Compared with the thick and heavy near-eye light field display system disclosed in the patent PCT15/481,467, the compact optical structure for light field display disclosed by the invention is more compact.
The details of embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain the principles of the invention.
FIG. 1 is a schematic diagram of a compact optical configuration for implementing a light field display.
Fig. 2 is a view projected through the open aperture set 1 at time t.
Fig. 3 is a view through the open aperture set 2 at time t + at/2.
Fig. 4 is a schematic diagram of one aperture cluster of the aperture group 1 being open at time t.
Fig. 5 is a schematic diagram of another aperture cluster of the aperture group 1 being open at time t + Δ t/4.
FIG. 6 is a schematic diagram of a compact optical configuration for light field display of an AR.
Detailed Description
The optical structure provided by the invention selects display screens with different emergent light polarization states in different areas, uses the polarization spectroscope as a light beam splitting and light fusion device, combines the reflection type phase modulation device and the wave plate, utilizes the characteristic that the reflection type phase modulation device is easy to realize a short-focus lens and the turning back of an optical path, and combines the monocular multi-view optical field technology of the earlier patent PCT15/481,467 to build a compact optical structure for optical field display.
One compact optical configuration for light field display is shown in fig. 1, and includes an imaging assembly, including a polarizing beam splitter 20, a display screen 10, two wave plates 31, 32, and two reflective modulators 41, 42, described below, a small pitch aperture array 50, a control unit 80, and a diaphragm 70. The system uses the polarization beam splitter 20 as a light beam splitting and merging device, which completely reflects the incident light beam with the polarization state of S state and completely transmits the incident light beam with the polarization state of P state. Here, the display panel 10 is exemplified by a group of 3 sub-panels, each of which displays and emits light information, and the polarization states of light emitted from adjacent sub-panels are different from each other in the S state and the P state. Here, the case where the S state is the polarization "" perpendicular to the xz-line and the P state is the polarization "" parallel to the xz-line will be described. After emergent light of the display screen 10 enters the polarized light beam splitter 10, emergent light of the S-state sub-screen 1 and the S-state sub-screen 3 is reflected and enters the wave plate 32 along the + z direction, the polarized light state is modulated into circular polarized light by the wave plate 32, the circular polarized light is reflected by the reflection modulation device 42 continuously along the + z direction, the circular polarized light enters the wave plate 32 for the second time along the-z direction and is modulated into a P state, and then the circular polarized light is transmitted through the polarized light beam splitter 20 and enters the small-pitch aperture array 50 along the-z direction. For clarity of illustration, double arrows are also used in the figures
Representing P-state polarization. Here, the wave plate 32 is described by taking an 1/4 wave plate as an example. The reflective modulation device 42 is a reflective imaging lens, and forms an enlarged virtual image of the sub-screen 1 and the sub-screen 3 on the EF surface, as shown in fig. 2. For convenience of explanation, the light beams from the sub-screen 1 and the sub-screen 3 incident on the small pitch aperture array 50 will be hereinafter equivalent to a sub-screen 1 virtual image outgoing light beam and a sub-screen 3 virtual image outgoing light beam, respectively. Modulation by 1/4 wave plate 32, compared with sub-panel 1 and sub-panelAnd 3, converting the polarization state of the emergent light beam into a P state by the S state of emergent light, the virtual image of the sub-screen 1 and the virtual image of the sub-screen 3. Along another light beam propagation path, after emergent light of the display screen 10 enters the polarized light beam splitter 10, emergent light of the P-state sub-screen 2 is transmitted, enters the wave plate 31 along the-x direction, is modulated into circular polarized light by the wave plate 31, continues to be reflected by the reflection modulation device 41 along the-x direction, enters the wave plate 31 along the + x direction for the second time and is modulated into the S state, then is reflected by the polarized light beam splitter 20, and enters the small-distance aperture array 50 along the-z direction. Here, the wave plate 31 is also exemplified by an 1/4 wave plate. The reflective modulation device 41 is a reflective imaging lens, and forms an enlarged virtual image for the sub-screen 2. Optimally, the reflection modulation devices 41 and 42 have the same phase modulation function and are symmetrically disposed about the splitting plane of the polarization beam splitter 20, so that the virtual image of the sub-screen 2 is also projected on the EF plane and is spliced with the virtual images of the sub-screens 1 and 3 to form the virtual image of the display screen 10. Similarly, the light beam from the sub-screen 2 incident on the small pitch aperture array 50 is equivalent to a virtual image emergent light beam of the sub-screen 2. Through the modulation of the 1/4 wave plate 31, compared with the P state of the light emitted from the sub-screen 2, the polarization state of the virtual image equivalent emitted light beam of the sub-screen 2 is converted into the S state, as shown in fig. 2. The reflective imaging device is easy to design a small focal length imaging lens, so the reflection modulation device 41 and the reflection modulation device 42 contribute to the compactness in the size of the optical structure shown in fig. 1. In addition, the reverse folding of the optical paths on the two light propagation paths also facilitates further compactness of the optical structure shown in fig. 1. The auxiliary modulation device 60 is composed of at least one phase modulation device, and is disposed between the display screen 10 and the small-distance aperture array 50 along the light beam propagation path direction, and is used as an equivalent imaging lens together with the reflection modulation device 41 or the reflection modulation device 42 to image each sub-screen of the display screen 10, so as to improve the imaging quality of each sub-screen by the single reflection modulation device 41 or the reflection modulation device 42, and further shorten the focal length of the equivalent lens for imaging each sub-screen of the display screen 10. Fig. 1 illustrates an example in which the auxiliary modulation device 60 is constituted by a phase modulation device disposed between the display screen 10 and the polarization beam splitter 20. It may also be placed between the polarizing beamsplitter 20 and the small pitch aperture array 50. When the auxiliary modulating device 60 is composed of two or more phase modulating devices, each phase modulatorThe elements may be positioned anywhere between the display screen 10 and the closely spaced array of apertures 50 along the path of travel of the light beams, respectively, as required by the optical design.
When each sub-screen virtual image equivalently emits light beams, light field display can be realized based on the technology described in the patent PCT15/481,467. Fig. 2 illustrates an example of a small-pitch aperture array including 6 apertures, i.e., M × N, 3 × 2, which includes a apertures arranged in the x direction11、A12、A21、A22、A31、A32The distance between adjacent apertures deltad in the x-direction is smaller than the diameter D of the pupil of the observerp. Wherein A is11、A21And A31Are a group and named as aperture group 1, A12、A22And A32The aperture groups 2 are formed, and N is 2, the aperture groups are staggered in sequence and are staggered. Each aperture may have a clear aperture size that is larger, equal, or smaller than the adjacent aperture spacing when open. The areas outside the apertures of the aperture array 50 are optically blocked by the stop 70. As mentioned above, along the x direction, the polarization states of the equivalent emergent light of the adjacent sub-screen virtual images are respectively P state "-" and S state "·". Along the x direction, A of aperture group 111、A21And A31Sequentially corresponding to the virtual images of the sub-screens 1, 2 and 3 one by one, and the A of the aperture group 212、A22And A32And the virtual images sequentially correspond to the sub-screen 1, the sub-screen 2 and the sub-screen 3 one by one. When each aperture is opened, the polarization direction of the allowed light is consistent with the polarization direction of the equivalent emergent light of the corresponding sub-screen virtual image. Specifically, the virtual image of the sub-screen 1 corresponds to the aperture a11And A12When the LED is turned on, only P-state light with the polarization state of- 'is allowed to pass through, and S-state light with the polarization state of-' is not allowed to pass through; the sub-screen 2 corresponds to the aperture A21And A22When the LED is turned on, only light with the polarization state of "·" S state is allowed to pass through, and light with the polarization state of "-" P state is not allowed to pass through; sub-screen 3 corresponding to aperture A31And A32When turned on, only P-state light with polarization state "-" is allowed to pass through, and S-state light with polarization state "·" is not allowed to pass through. In each time period Δ t, the control unit 80 controls the N-2 aperture groups to be sequentially and cyclically opened at time intervals of Δ t/N- Δ t/2.Specifically, taking time period t-t + Δ t as an example, at time t, the aperture A of the aperture group 111、A21、A31Open, aperture A of aperture group 212、A22、A32In the closed state, as shown in fig. 2. The display screen synchronously projects a view of the scene to be displayed with respect to the set of open apertures 1. The display screen projects a view of a scene to be displayed about a corresponding open aperture group, a view distribution area of the view distribution area is a display screen virtual image area, and a viewpoint is an intersection point of straight lines which respectively pass through each sub-screen virtual image area and correspond to apertures of the sub-screen virtual images in the aperture group 1. Under the optimal condition that the sub-screens and the apertures are arranged at equal intervals, the optimal point is the intersection point of the centers of the virtual images of the sub-screens and the connecting line of the centers of the corresponding apertures of the virtual images of the sub-screens in the aperture group 1, such as VP1 in fig. 2. Another view determining method is to determine views of one sub-screen virtual image and one aperture respectively, that is, a view corresponds to a combination of each sub-screen virtual image and each aperture, for example (sub-screen 1 virtual image-a)21) And (6) view. In A21When the screen is opened, the sub-screen 1 virtual image is loaded (sub-screen 1 virtual image-A)21) And (6) view. (virtual sub-screen 1-A)21) The view projection area is a virtual image area of the sub-screen 1, and the corresponding viewpoints are virtual image edge points and an aperture A of the sub-screen 121The edge point connecting line encloses an area, optimally the aperture A21A center point. And determining the other sub-screen virtual images and the views of the corresponding apertures in the same way. The view determination method is described in the earlier patent PCT15/481,467. As in fig. 3, at t + Δ t/2, only aperture set 2 is open, and the corresponding view is projected to viewpoint VP2 in the same way. The small-spacing apertures are adjacently arranged at a space spacing smaller than or equal to the diameter of the pupil, so that the spacing between the VP1 point and the VP2 point which are slightly larger than the spacing can enable the two views loaded and displayed at the two moments to respectively enter eyes of a viewer through different areas of the pupil under the condition of reasonable delta d value. And when the delta t is small enough, the two light beams are superposed to form a display object point which can be naturally focused by the corresponding eyes based on the visual retention, so that the problem of focusing-converging conflict inherent in the traditional stereoscopic vision technology is solved.
The above embodiment is described by taking the case where "" polarized perpendicular to the xz-line is in the S state and "" polarized parallel to the xz-line is in the P state. In fact, the S and P states may take other situations, such as left-handed and right-handed polarization states.
In the process, the same sub-screen virtual image has 2 apertures corresponding to the 2 aperture groups, and the belonged groups can be exchanged; and the timing of the opening of the 2 aperture groups can be switched.
In the above embodiment, when one aperture group is opened, one sub-screen virtual image equivalent emergent light cannot pass through the nearest adjacent aperture of the corresponding aperture in the aperture group, but can pass through the apertures in the aperture group that are spaced from the corresponding aperture by 1, or 3, or more odd number of apertures (when the number of M is large enough), and these light information passing through the non-corresponding apertures have the same polarization state as the corresponding apertures, and will exist as noise if received by eyes. Especially, through the noise of the same polarization state aperture which is closest to the corresponding aperture, the distribution area of the noise is closest to the viewpoint of the display view, and the interference of the noise to the 3D presenting scene is the largest, as shown in fig. 2, the virtual image of the sub-screen 1 equivalently emits light through the aperture A31The noise generated.
The aperture groups opened at the same time point are expanded to be distributed and opened at more time points, so that the adjacent apertures (allowing the light-transmitting polarization states to be the same) in the same aperture group in the same polarization state are opened at different time points, and meanwhile, the sub-regions corresponding to the unopened apertures do not load information, so that the noise can be inhibited. Also explained using the structure described in fig. 1, the variation is that the virtual sub-screen images are no longer loaded with information at the same time. Specifically, in each aperture group, starting from a first aperture in the + x direction, two adjacent apertures having different polarization states are combined into a first aperture pair, and then in the aperture group, starting from the first aperture behind the first aperture pair, the same method defines a second aperture pair, and the same is repeated to determine all the aperture pairs in the aperture group, wherein when M is an odd number, the last aperture is singly used as one aperture pair. In the small pitch aperture array 50 shown in fig. 2, V is 2, and a of the aperture group 1 is set to be a11And A21Is an aperture pair, A31An aperture pair is formed independently; a of aperture group 212And A22Is a pair of apertures, and the aperture is a single aperture pair,A32one aperture pair alone. The 4 aperture pairs are each regarded as an independent aperture cluster, and only one aperture cluster is opened in sequence at 4 time points within a time period Δ t. When M is large, each aperture cluster will contain a plurality of spaced aperture pairs. When one aperture is opened, the corresponding sub-screen virtual image loading information is controlled, and the non-opened aperture corresponding to the sub-screen virtual image does not load information. In FIG. 4, at time t, only aperture A11And A21The aperture cluster is opened, and the corresponding sub-screen 1 virtual image and sub-screen 2 virtual image are respectively loaded about the aperture A11And A21The information of (1). The virtual image of the sub-screen 3 is not loaded with information, and the figure indicates that no information is loaded by an X. And the information of the sub-screen virtual image about one aperture is the information distribution of the display screen virtual image area about the aperture group view to which the aperture belongs on the sub-screen virtual image area. Similarly, the view of the display screen virtual image region about one aperture group is that the viewpoint of the view passes through the intersection point of the corresponding aperture straight line of each sub-screen virtual image region and the sub-screen virtual image region in the aperture group, and under the optimal condition that the sub-screens and the apertures are arranged at equal intervals, the optimal intersection point is the intersection point of the connecting line of the corresponding aperture centers of each sub-screen virtual image center and the sub-screen virtual image in the aperture group. At time t + Δ t/4, the aperture A11And A21The aperture cluster of composition is closed, A31As an aperture cluster opens, sub-screen 3 virtual image loading is relative to aperture a31The virtual image of the sub-screen 1 and the virtual image of the sub-screen 2 are not loaded with information. At time points t +2 Δ t/4 and t +3 Δ t/4, respectively, only A12And A22Open and only A32And opening and synchronously loading corresponding information in the same way. Similarly, when the light information of the two views can be incident to one eye of an observer, the light field display can be realized based on the monocular multi-view. As above (virtual image-A of sub-screen 1)21) Another view determination method, which is exemplified by a view, is also applicable here in the same way.
In the above embodiment, the same sub-screen virtual image may be exchanged in the N apertures corresponding to each aperture group; the timing of the opening of the N aperture clusters can be switched.
In the above embodiment, virtual sub-screens with different polarization states are superposed on one surface. Actually, virtual images of the sub-screens in different polarization states may not overlap in the-z direction, that is, the two reflective modulation devices 41 and the auxiliary modulation device 60 make the equivalent focal lengths of the sub-screens in different polarization states different when the sub-screens are imaged. At this time, the sub-screen virtual images of different surfaces can be respectively subjected to image loading.
The compact structure shown in fig. 1 can be placed directly in front of one eye of an observer to serve as an eyepiece of the head-mounted VR, and two such compact structures can build the head-mounted VR system. In addition, the compact structure may further include a deflecting device 90. The deflecting device 90 is placed in front of the small pitch aperture array in the exit direction of the light beam, and the projected information of the structure shown in fig. 1 is introduced into one pupil of the observer by path deflection, and at the same time, the deflecting device 90 allows light of the external environment to enter, as shown in fig. 6. The external ambient light is the light information reflected or emitted by the scene of the environment in which the viewer is located. Here, the auxiliary modulation device 60 is composed of phase modulation devices 601, 602, and 603, which are respectively disposed at different positions on the light beam transmission path shown in fig. 6, and cooperate with the reflection modulation devices 41 and 42 to respectively image sub-screens of different polarization states. The phase modulating devices 601, 602, 603 are each a lens. With respect to fig. 1, the depth of the scene shown in fig. 6 is shifted from the z-direction to the x-direction, and the entire assembly needs to be mirrored with respect to the deflecting device 90 before the acquisition process of the loading view is performed. The structure shown in fig. 6 can be used as an eyepiece of AR, and a light field AR system can be built by two structures. Fig. 6 illustrates the function of the deflection device 90 by way of example only of one slanted reflective/transmissive face. In other embodiments, various beam deflecting devices, such as a free-form surface reflecting surface, etc., which are used in a conventional AR system, may be used instead of the inclined reflecting/transmitting surface structure shown in fig. 6, as the deflecting device of the present invention.
The above is only a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any insubstantial modifications made by using the design concept fall within the scope of the present invention. For example, the exclusive use of this feature is not limiting. Accordingly, all such related embodiments are intended to be within the scope of the following claims.
Claims (12)
1. A compact optical structure for light field display comprising an imaging assembly, the imaging assembly comprising:
the polarization beam splitter completely reflects the incident beam with the polarization state of S state and completely transmits the incident beam with the polarization state of P state;
the display screen is arranged at a position corresponding to the polarizing beam splitter, so that light information emitted by each sub-screen is incident to the polarizing beam splitter respectively, the polarization state of emergent light of adjacent sub-screens is one of S state and P state respectively, and the polarization states of emergent light of adjacent sub-screens are different from each other, wherein M is not less than 2;
the two wave plates are respectively arranged in front of the polarization beam splitter along the transmission light transmission direction and the reflection light transmission direction of the polarization beam splitter and are used for changing the polarization state of an incident light beam, so that the P-state light beam passing through the wave plates twice is changed into an S-state light beam, and the S-state light beam passing through the wave plates twice is changed into a P-state light beam;
the two reflection modulation devices are used for carrying out phase modulation on light, correspond to the two wave plates respectively, reflect light beams incident through the corresponding wave plates respectively, enable the light beams to enter the corresponding wave plates for the second time in a reverse direction, and then enter the polarization beam splitter again, and the two reflection modulation devices are respectively formed into amplified virtual images of each S-state sub-screen and each P-state sub-screen;
the imaging assembly is set to be capable of projecting M sub-screen virtual images arranged in the + x direction to the + z direction, and display screen virtual images formed by the M sub-screen virtual images are transmitted along the-z direction; the polarized light states of the equivalent emergent light of the adjacent sub-screen virtual images are respectively one of an S state and a P state, and the polarized light states of the equivalent emergent light of the adjacent sub-screen virtual images are different from each other;
the compact optical structure further comprises:
small-spacing aperture array with M × N adjacent spacing along + x direction smaller than pupil diameter D of observerpIs placed in front of the imaging assembly along the-z direction, and M apertures spaced by N-1 apertures are respectively grouped,the N aperture groups are staggered in the x direction, the apertures are staggered in the x direction, in the + x direction, the M apertures in each aperture group correspond to the M sub-screen virtual images in sequence one by one, the polarization state of light allowed to pass through when each aperture is opened is consistent with the equivalent emergent light polarization state of the corresponding sub-screen virtual image, and N is not less than 2;
the control unit controls the N aperture groups to be opened in sequence only by one group at each N adjacent time points, and controls the display screen to synchronously project a view of a scene to be displayed relative to the opened aperture group;
the display screen projects a view of a scene to be displayed relative to a corresponding open aperture group, the view projection area is a virtual image coverage area of each sub-screen of the display screen, and a viewpoint is an intersection point of straight lines which respectively pass through each virtual image area of the sub-screen and a corresponding aperture of the virtual image of the sub-screen in the open aperture group;
and the diaphragm is arranged at the small-spacing aperture array and used for blocking the transmission part of emergent light from the display screen in the area except the small-spacing apertures.
2. The compact optical structure for light field display according to claim 1, wherein the imaging assembly further comprises: and the auxiliary modulation device consists of at least one phase modulation device, is arranged on the transmission path of the emergent light beam of the display screen, is matched with the two reflection modulation devices, and respectively forms the amplified virtual images of each S-state sub-screen and each P-state sub-screen.
3. A compact optical structure for light field display as claimed in any one of claims 1-2 wherein the corresponding N apertures of the same virtual sub-screen image in the N aperture groups are switchable, and the timing of the opening of the N aperture groups is switchable.
4. The compact optical structure for light field display according to any one of claims 1-2, wherein the display screen projects a view of a scene to be displayed with respect to a corresponding open aperture group, the view projection area is a virtual sub-screen image coverage area of the display screen, and the viewpoint is an intersection point of a virtual sub-screen image center and a connecting line of the virtual sub-screen image with the corresponding aperture center in the open aperture group.
5. A compact optical structure for light field display as claimed in any one of claims 1-2 further comprising a deflection device for deflecting the light beam passing through said array of closely spaced apertures and directing it to the pupil of an observer; the deflection device allows light from the external environment to be transmitted into the observer's pupil.
6. A compact optical structure for light field display as claimed in claim 3 further comprising a deflection device for deflecting the light beam passing through said array of closely spaced apertures and directing it to the pupil of an observer; the deflection device allows light from the external environment to be transmitted into the observer's pupil.
7. A compact optical structure for light field display comprising an imaging assembly, the imaging assembly comprising:
the polarization beam splitter completely reflects the incident beam with the polarization state of S state and completely transmits the incident beam with the polarization state of P state;
the display screen is arranged at a position corresponding to the polarizing beam splitter, so that light information emitted by each sub-screen is incident to the polarizing beam splitter respectively, the polarization state of emergent light of adjacent sub-screens is one of S state and P state respectively, and the polarization states of emergent light of adjacent sub-screens are different from each other, wherein M is not less than 2;
the two wave plates are respectively arranged in front of the polarization beam splitter along the transmission light transmission direction and the reflection light transmission direction of the polarization beam splitter and are used for changing the polarization state of incident light, so that the P-state light beams passing through the wave plates twice are changed into S-state light beams, and the S-state light beams passing through the wave plates twice are changed into P-state light beams;
the two reflection modulation devices are used for carrying out phase modulation on light, correspond to the two wave plates respectively, reflect the light beams incident through the corresponding wave plates respectively, enable the light beams to be incident into the corresponding wave plates for twice in a reverse direction, and then enter the polarization beam splitter again; the two reflection modulation devices are respectively formed into amplified virtual images of each S-state sub-screen and each P-state sub-screen;
the imaging assembly is set to be capable of projecting M sub-screen virtual images arranged in the + x direction to the + z direction, and display screen virtual images formed by the M sub-screen virtual images are transmitted along the-z direction; the polarized light states of the equivalent emergent light of the adjacent sub-screen virtual images are respectively one of an S state and a P state, and the polarized light states of the equivalent emergent light of the adjacent sub-screen virtual images are different from each other;
the compact optical structure further comprises:
small-spacing aperture array with M × N adjacent spacing along + x direction smaller than pupil diameter D of observerpThe aperture composition is arranged in front of the imaging assembly along the-z direction, M apertures spaced by N-1 apertures are respectively grouped, the N grouped aperture groups are staggered by one aperture along the + x direction, and along the + x direction, the M apertures in each aperture group and the M sub-screen virtual images sequentially correspond one by one, the polarization state of passing light is allowed when each aperture is opened, and the polarization state of equivalent emergent light of the corresponding sub-screen virtual images is consistent, wherein N is not less than 2;
in each aperture group, starting from a first aperture along the + x direction, two adjacent apertures with different polarization states form a first aperture pair, then in the aperture group, starting from the first aperture behind the first aperture pair, defining a second aperture pair by the same method, repeating the steps, and determining all the aperture pairs in the aperture group, wherein when M is an odd number, the last aperture of the drop list is independently used as an aperture pair;
the control unit is used for opening only one aperture cluster in V aperture clusters formed by aperture pairs which are sequentially spaced by V-1 aperture pairs in one aperture group at a time point, and controlling N multiplied by V different aperture clusters of all the aperture groups to be opened sequentially at N multiplied by V time points which are adjacent within each time period delta t, wherein 2 is less than or equal to V less than or equal to [ (N +1)/2], [ ] is an integer symbol;
when only one aperture is opened, controlling the corresponding sub-screen to load information;
the loading information of the sub-screen corresponding to one aperture is information of a view of an aperture group to which the aperture belongs in a virtual image area of the display screen on a virtual image corresponding to the sub-screen;
the view of the display screen virtual image area relative to one aperture group, wherein the viewpoint of the view is the intersection point of straight lines which respectively pass through each sub-screen virtual image area and the corresponding aperture of the sub-screen virtual image area in the aperture group;
and the diaphragm is arranged at the small-spacing aperture array and used for blocking the transmission part of emergent light from the display screen in the area except the small-spacing apertures.
8. The compact optical structure for light field display according to claim 7, wherein the imaging assembly further comprises: and the auxiliary modulation device consists of at least one phase modulation device, is arranged on the transmission path of the emergent light beam of the display screen, is matched with the two reflection modulation devices, and respectively forms the amplified virtual images of each S-state sub-screen and each P-state sub-screen.
9. A compact optical structure for light field display as claimed in any one of claims 7 to 8 wherein the grouping of corresponding N apertures in a group of N apertures for the same virtual sub-screen image is switchable and the timing of the opening of the group of N apertures is switchable.
10. A compact optical structure for light field display as claimed in any of claims 7 to 8 wherein the view of the virtual image area of the display screen with respect to an aperture group is from the point of view of the intersection of the centre of each virtual sub-screen image and the line joining the centres of the corresponding apertures in the aperture group.
11. A compact optical structure for light field display as claimed in any one of claims 7 to 8 further comprising deflecting means for deflecting the light beams passing through said array of closely spaced apertures and directing them to the pupils of the observer; the deflection device allows light from the external environment to be transmitted into the observer's pupil.
12. A compact optical structure for light field display as claimed in claim 9 further comprising a deflection device for deflecting the light beam passing through said array of closely spaced apertures and directing it to the viewer's pupil; the deflection device allows light from the external environment to be transmitted into the observer's pupil.
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