Detailed Description
The present application will be described in further detail with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant application and are not limiting of the application. It is obvious to a person skilled in the art that other figures can also be derived from these figures without inventive effort. It should be noted that, for convenience of description, only the portions related to the present application are shown in the drawings.
Like numbers refer to like elements throughout the specification. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In addition, the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
A display system includes an image generation module, an adjustable polarizer, and a polarization multiplex holographic element. The image generation module projects image light; the adjustable polaroid is arranged in a propagation path of the image light projected by the image generation module and is used for adjusting the polarization angle of the image light; and the polarization multiplexing volume holographic element receives and diffracts the image light which is subjected to polarization adjustment by the adjustable polarizing plate, and images the diffracted image light at a corresponding specific position according to the polarization angle of the image light. The display system provided by the application has a display function with adjustable focus. In this embodiment, the image light is a light ray carrying image information projected by the image generation module. The adjustable polaroid can adjust the polarization angle of the image light according to needs, and the polarization angle is not unique. Meanwhile, the specific position where the polarization multiplexing volume holographic element images the image light is not unique. The polarization angle of the image light after polarization adjustment corresponds to the specific imaging position of the polarization multiplexing body holographic element one by one, so that the polarization angle of the image light is adjusted by controlling the polarizing film according to the change requirement of the specific imaging position, and finally the change imaging of the system at different specific positions is realized. Wherein a particular location refers to a specific location where the polarization multiplex volume holographic element images the image light at different projection distances.
According to the embodiment of the application, the display system further comprises a control module, and the control module adjusts the rotation angle of the adjustable polarizer so as to adjust the polarization angle of the image light by the adjustable polarizer.
According to an embodiment of the present application, the polarization angle is 0 ° or 90 °. In this embodiment, the polarization angle of the image light incident to the polarization multiplexing volume hologram element after polarization adjustment may be 0 ° or 90 °, as necessary.
According to the embodiment of the present application, the focal point corresponding to the specific position where the image light is imaged includes a first focal point and a second focal point, and a first focal length corresponding to the first focal point and a second focal length corresponding to the second focal point are different; when the polarization angle of the image light is 0 degrees, the polarization multiplexing body holographic element has a first focal length, namely the polarization multiplexing body holographic element converges the image light at a first focus; and when the polarization angle of the image light is 90 degrees, the polarization multiplexing body holographic element has a second focal length, namely the polarization multiplexing body holographic element converges the image light at a second focal point. In the present embodiment, when the image light is incident to the polarization multiplexing volume hologram element when the polarization angle of the image light is a specific 0 ° or 90 °, the volume hologram element displays two specific focal points. The polarization multiplexing volume hologram element has two focal points corresponding to image light incident at a specific polarization angle of 0 ° or 90 ° before being disposed in the display system.
According to the embodiment of the present application, when the polarization angle of the image light is between 0 ° and 90 °, the polarization multiplexed volume hologram element will have both the first focal length and the second focal length. That is, when image light having a polarization angle between 0 ° and 90 ° is incident on the polarization multiplexing volume hologram element, the polarization multiplexing volume hologram element images the image light at a specific position corresponding to the first focal point and the second focal point.
According to the embodiment of the application, the polarization multiplexing body holographic element is made of polarization sensitive materials, so that the polarization multiplexing body holographic element is convenient to manufacture and use.
According to an embodiment of the present application, the polarization multiplex volume hologram element may be a reflective hologram element. When the image generation module is on the same side of the polarization multiplex holographic element as the viewpoint, the polarization multiplex holographic element can be a reflective holographic element. The image light is reflected by the polarization multiplexing volume holographic element and then imaged at a corresponding projection distance.
According to an embodiment of the present application, the polarization multiplex volume hologram element may be a transmissive hologram element. When the image generation module and the observation point are respectively arranged at two sides of the multiplexing volume holographic element, the polarization multiplexing volume holographic element can be a transmission type holographic element. The image light is transmitted by the polarization multiplexing volume holographic element and then imaged at a corresponding projection distance.
According to the embodiment of the present application, the polarization multiplexing volume hologram element is a phase type hologram element. The phase type hologram element has no loss of optical energy and can realize diffraction of up to 100% in theory. The display system in the embodiment of the application uses the phase-type polarization multiplexing holographic element, and can realize higher-brightness display.
According to an embodiment of the present application, an image generation module includes a light source and a display device.
According to an embodiment of the application, the light source is a laser or LED light source.
According to an embodiment of the present application, the display device is an LCD display, an LCOS display, or a DLP display.
According to an embodiment of the present application, the display system further includes a viewpoint tracking system that tracks a viewpoint of a user and transmits the tracked viewpoint to the control module; the control module adjusts a rotation angle of the adjustable polarizer based on the tracked viewpoint. When the viewpoint tracking system tracks the eyes of the user to look near, the viewpoint conclusion is transmitted to the control module. The control module adjusts the rotation angle of the adjustable polaroid to be an angle corresponding to the close-looking of human eyes. The rotation angle may be 0 ° in the present embodiment. At this time, the polarization angle of the image light is adjusted to 0 °, so that the volume hologram element has the first focal length. At this time, the display image of the display system is at a first projection distance corresponding to the first focal length. Similarly, when the eye tracking system tracks the eyes of the user to see far, the viewpoint conclusion is transmitted to the control module. The control module adjusts the rotation angle of the adjustable polaroid to be an angle corresponding to the close-looking of human eyes. The rotation angle may be 90 ° in the present embodiment. At this time, the polarization angle of the image light is adjusted to 90 °, so that the volume hologram element has the second focal length. At this time, the display image of the display system is at a second projection distance corresponding to the second focal length. When the image is displayed as a real image, the first projection distance is smaller than the second projection distance; when the image is displayed as a virtual image, the first projection distance is greater than the second projection distance.
According to the embodiment of the application, the incident light and the reference light have the same wavelength, the same angle reaching the polarization multiplexing volume holographic element and the like, so that the image display distance of the display system can be adjusted according to different polarization states of the incident light.
According to embodiments of the present application, the adjustable polarizer may be adjusted by manual control.
According to embodiments of the present application, the adjustable polarizer may be mechanically self-adjusting.
The polarization multiplexing volume hologram element provided in the display system of the present application is prepared in advance. Before the specific application, the polarization multiplexing volume hologram element has a characteristic of converging image light at a plurality of different focal points. In the specific embodiments of the present application, two focal points are mainly involved, but this is only an exemplary illustration.
The following description will be made of the fabrication of the polarization multiplexing hologram element. The manufacturing steps mainly comprise:
(1) and determining the closest projection distance and the farthest projection distance of the display system according to the application requirements of the display system in the actual scene.
(2) And based on the geometric imaging model, calculating focal lengths corresponding to the shortest projection distance and the farthest projection distance of the polarization multiplexing volume holographic element and the display system according to the shortest projection distance, the farthest projection distance and the object distance in the display system, wherein the focal lengths are respectively a first focal length and a second focal length.
(3) Two beams of coherent polarized light with the same polarization angle are emitted to the surface of the polarization sensitive material at a certain included angle, interference reaction is carried out on the surface of the material, and the position of the second interference reaction is the same as the position of the first interference reaction; the two polarized light beams can be a first reference light and a first object light with a polarization angle of 0 degree and a second reference light and a second object light with a polarization angle of 90 degrees respectively; when a light source emits first reference light and first object light with a polarization angle of 0 degree to an optical lens at a certain included angle, two beams of light interfere on the surface of the material, so that the material has a first focal length corresponding to the nearest projection distance; on the basis, second reference light and second object light with the polarization angle of 90 degrees are emitted to the surface of the material again at the same included angle, and the position of the material is adjusted to enable the position of the second interference reaction on the surface of the material to be the same as the position of the first interference reaction, so that the volume hologram element has the first focal length and simultaneously has the second focal length corresponding to the farthest projection distance, and the manufacture of the polarization multiplexing volume hologram element is completed. The light source for emitting the reference light and the object light is the same laser light source, and the included angle of the two polarized light beams can be specifically adjusted according to the performance parameters of the designed polarization multiplexing holographic element.
(4) And after the polarization multiplexing volume holographic element is manufactured, a system is built according to an actual application scene. The image generation module generates image light. The polarization multiplexing volume hologram element performs projection display of the image light generated by the image generation module. The adjustable polaroid is arranged between the image generation module and the polarization multiplexing holographic element and is used for changing the polarization state of incident light.
The volume hologram element used in the present application is a polarization multiplexed volume hologram element. When the polarization multiplexing volume holographic element is manufactured, the reference light with the polarization angle of 0 degree and the object light are subjected to first interference on the surface of the polarization sensitive material, and the reference light with the polarization angle of 90 degrees and the object light are subjected to second interference at the same position of the surface of the material, so that the polarization multiplexing volume holographic element with 2 imaging focuses is obtained. The combination of the image generation module and the adjustable polaroid projects incident light with different polarization angles to the polarization multiplexing holographic element, and the polarization multiplexing holographic element presents different focal lengths according to different polarization angles of the incident light, so that the variable focus display system is formed.
The display system provided by the embodiment of the application utilizes the multiplexing characteristic of volume holograms to multiplex volume hologram elements with different focal lengths together. When light meeting the Bragg condition is incident to the surface of the polarization multiplexing volume holographic element, the polarization multiplexing volume holographic element presents different focal lengths, so that imaging at different distances is realized. In addition, compared with the traditional volume holographic material, the volume holographic element has the advantages of thinner thickness, smaller volume and more flexible regulation and control performance, and has simple structure and convenient use.
The display system provided by the embodiment of the application utilizes the polarization multiplexing holographic element to realize the change of the focal length of the imaging system, thereby changing the projection distance, greatly reducing the cost of the whole display system compared with a method for changing the object distance by a spatial light modulator, and increasing the practicability.
The display system provided by the embodiment of the application is based on the characteristics of the polarization multiplexing body holographic element, and when the polarization angle of incident light is other angles except 0 degree and 90 degrees, the polarization multiplexing body holographic element can simultaneously present two different focuses, so that the whole display system simultaneously forms the same image at two distances, and double-focus display is realized.
The polarization multiplexing volume hologram element in the display system provided by the embodiment of the application is a phase volume hologram element. It has no loss of light energy and can theoretically realize diffraction of up to 100%. Therefore, the display system using the polarization multiplexing volume holographic element to realize zooming in the embodiment of the application can realize higher-brightness display when light with the same intensity is incident.
Fig. 1 is a schematic diagram of a display system setup provided in the present application. As shown in fig. 1, the establishing process mainly includes determining a projection distance 10, determining a focal length 20, fabricating a polarization multiplexing volume hologram element 30, and constructing a display system 40.
FIG. 2 is a schematic diagram of an optical path for making a polarization multiplexing holographic element shown in the present application. As shown in fig. 2, when the polarization multiplexing volume hologram element is manufactured, theobject light 100 and thereference light 101 having a polarization angle of 0 ° enter the polarization multiplexingvolume hologram element 203 at a certain angle, and a first interference reaction occurs on the lens surface. The polarization multiplexvolume hologram element 203 displays a firstfocal point 204; the object light 200 and the reference light 201 with the polarization angle of 90 degrees are incident to the polarization multiplexingvolume hologram 203 at the same included angle, and the relative positions of the polarization multiplexingvolume hologram 203 and the light source are adjusted, so that the two polarized lights are interfered for the second time at the position of the polarization multiplexing volume hologram where the first interference occurs. The polarization multiplex holographic element now shows the secondfocal point 205. The first focal length corresponding to the first focal point is smaller than the second focal length corresponding to the second focal point.
Fig. 3 is a schematic diagram illustrating a change in focal length of a polarization multiplexing holographic element provided in the present application. As shown in fig. 3, after the polarizationmultiplex volume hologram 300 is manufactured, by changing the polarization state of incident light, it is possible to realize that different focal lengths are displayed in the polarizationmultiplex volume hologram 300. When the polarization angle of the incident light is 0 °, the volume hologram element displays afirst focus 301; when the polarization angle of the incident light is 90 °, the volume hologram element displays asecond focus 302; when the polarization angle of incident light is between 0 ° and 90 °, the volume hologram element simultaneously displays thefirst focus 301 and thesecond focus 302.
Fig. 4 is a model schematic diagram of a geometric imaging model shown in the present application. As shown in FIG. 4The geometric imaging model mainly comprises 3 quantities, namely a projection distance L and an object distance L`And a focal length f. An image emitted from the image generating unit (PGU)400 through thediffuser 401 and the deflecting means 402 passes through the polarization multiplexingvolume hologram element 403 and then is formed into an enlarged virtual image to be observed by thehuman eye 404. By adjusting the polarization state of the incident light, the focal length f corresponding to the polarization multiplexingvolume hologram element 403 is different. According to the imaging formula (1), under the condition that the object distance L' is not changed, the focal length f is different, and the corresponding projection distance L is different, so that the projection distance of the display system can be adjusted by adjusting the polarization state of incident light.
Example one
Fig. 5 is a schematic diagram of a variable focus projector apparatus according to a first embodiment of the present application. As shown in fig. 5, the projector includes animage generation module 500, anadjustable polarizer 501, acontrol module 502, and a polarization multiplexing volumehologram element body 503. Theimage generation module 500 generates and projects the required image light to the polarization multiplexingvolume hologram element 503; the image light generated by theimage generation module 500 is located between theimage generation module 500 and the polarizationmultiplex volume hologram 503; thetunable polarizer 501 is placed between theimage generation module 500 and thepolarization multiplex hologram 503; the control block 502 controls the rotation angle of the adjustablepolarizing plate 501 to adjust the polarization angle of the image light incident to the polarization multiplexingvolume hologram element 503. When the rotation angle of thetunable polarizer 501 is 90 °, the polarization angle of the polarization-adjusted incident light is 90 °, and according to the bragg condition, the focal length corresponding to the polarization multiplexingvolume hologram 503 is the first focal length f1, and the projection distance a of the entire display system can be calculated from the position of the image and the first focal length f 1. Similarly, when the rotation angle of theadjustable polarizer 501 is 0 °, the polarization angle of the polarization-adjusted incident light is 0 °, the focal length corresponding to the polarization multiplexingvolume hologram 503 is the second focal length f2, and the projection distance b of the entire display system can be calculated from the position of the image and the secondfocal length f 2. Specifically, when the angle of the tunablepolarizing plate 501 is any angle other than 0 ° and 90 °, thepolarization multiplex hologram 503 exhibits the first focal length f1 and the second focal length f2 at the same time. Correspondingly, the display system presents images at both projection distance a and projection distance b.
Example two
Fig. 6 is a schematic structural view of a depth-of-field adjustable nano-lens display system according to a second embodiment of the present application. As shown in fig. 6, the nanolens display system includes amicro-projection system 600, acoupling region 601, awaveguide region 602, a polarization multiplexholographic element 603, anadjustable polarizer 604, aviewpoint tracking system 605, and acontrol system 606. Themicro-projection system 600 generates image light carrying image information.Coupling region 601 couples image light generated bymicro-projection system 600 towaveguide region 602; thewaveguide region 602 transmits the image light generated by themicro-projection system 600 to the polarization multiplexingvolume hologram element 603; theadjustable polarizer 604 changes the polarization angle of the image light produced by themicro-projection system 600. Theviewpoint tracking system 605 tracks the viewpoint of the human eye and determines the distance from the human eye to the front. When viewpoint-trackingsystem 605 concludes that the human eye is looking in the near direction, a command is passed to controlsystem 606 andcontrol system 606 rotatesadjustable polarizer 604 by an angle of rotation of 90 ° such that the angle of polarization ofadjustable polarizer 604 is 90 °. When the image light reaches the polarization multiplexingvolume hologram 603 after passing through thecoupling region 601 and thewaveguide region 602, the focal length corresponding to the polarization multiplexingvolume hologram 603 is the first focal length f1 according to the bragg condition. The depth of field a of the near-eye display system is calculated from the position of the image and the first focal length f 1. At this time, the human eye can observe the depth a image. Similarly, when eye-trackingsystem 605 concludes that the human eye is looking farther away,control system 606 rotates the angle of rotation ofadjustable polarizer 604 to 0 ° such that the angle of polarization ofadjustable polarizer 604 is 0 °. The depth of field b of the near-to-eye display system can now be calculated from the position of the image and the second focal length f2 of the polarizationmultiplex volume hologram 603. The human eye can observe the depth b image. Specifically, when the rotation angle of thetunable polarizer 604 is any angle other than 0 ° and 90 °, the polarization multiplexingvolume hologram 603 simultaneously exhibits the first focal length f1 and the second focal length f2, and accordingly the display system simultaneously exhibits the depth of field a and the depth of field b.
EXAMPLE III
Fig. 7 is a schematic structural diagram of a head-up display system according to a third embodiment of the present application. As shown in fig. 7, the display system comprises animage generation module 700, aturning device 701, anadjustable polarizer 702, apolarization multiplex hologram 703, awindshield 704, aviewpoint tracking system 705, and acontrol module 706. Theimage generation module 700 projects image light carrying relevant information on the instrument panel to thesteering device 701. Theturning device 701 receives the image light generated by theimage generation module 700 and projects it to the polarization multiplexingvolume hologram element 703. The polarization multiplexinghologram element 703 is attached to the surface of thewindshield 704. On the one hand, the polarization multiplexingvolume hologram element 703 forms a virtual image outside thewindshield 704 by the incident light; on the other hand, the polarization multiplexingvolume hologram element 703 diffracts incident light to the human eye. Theviewpoint tracking system 705 tracks the distance of the driver and transmits the conclusion to thecontrol module 706; thecontrol module 706 receives the command and rotates the angle of theadjustable polarizer 604 as commanded.
Specifically, wheneye tracking system 705 concludes that the human eye is looking farther away, a command is passed to controlmodule 706. Thecontrol module 706 rotates theadjustable polarizer 702 by a rotation angle of 90. When the image light reaches the polarization multiplexingvolume hologram element 703 via theturning device 701, the focal length corresponding to the polarization multiplexingvolume hologram element 703 is the first focal length f1 according to the bragg condition. The projection distance a of the head-up display system can be calculated from the position of the image and the focal length f 1. The human eye can see a virtual image 1 at a distance. Similarly, when theviewpoint tracking system 705 concludes that the human eye is looking in the near direction, the polarization angle of theadjustable polarizer 702 is 0 °, and the projection distance b of the head-up display system can be calculated from the position of the image and the second focal length f2 of the polarization multiplexingvolume hologram 703. The human eye sees avirtual image 2 at close proximity. Specifically, when the angle of thetunable polarizer 702 is any angle other than 0 ° and 90 °, the polarizationmultiplex hologram element 703 exhibits the first focal length f1 and the second focal length f2 at the same time, and accordingly the head-up display system will form virtual images at the projection distance a and the projection distance b at the same time.
Example four
FIG. 8 is a schematic diagram illustrating the fabrication of a dual view point polarization multiplexing volume hologram element according to example four shown in the present application. As shown in fig. 8, when the dual view point polarization multiplexing holographic element is manufactured,reference light 100 with a polarization angle of 0 ° and object light 200 with a polarization angle of 0 ° generated by the same laser source are incident on the surface of the polarization sensitive optical lens at a certain included angle to generate a first interference reaction, so as to form a view point a of a driver; thereference light 101 with the polarization angle of 90 degrees and the object light 201 with the polarization angle of 90 degrees, which are generated by the same laser light source, are incident on the surface of the polarization sensitive optical lens at the same included angle, and a second interference reaction occurs at the position where the first interference reaction occurs, so that the viewpoint b of the co-driver is formed. The included angle of the light beams can be specifically adjusted according to the performance parameters of the designed polarization multiplexing holographic element.
Fig. 9 is a schematic structural diagram of a dual-viewpoint heads-up display system according to a fourth embodiment of the present application. As shown in fig. 9, the dual view point head-up display system apparatus includes animage generation module 900, aturning device 901, anadjustable polarizer 902, a polarization multiplexingvolume hologram 903, and awindshield 904. Theimage generation module 900 projects image light carrying relevant information on the instrument panel to thesteering device 901. Theturning device 901 receives the image light generated by theimage generation module 900 and projects it to the polarization multiplexingvolume hologram element 903. The polarization multiplexingvolume hologram 903 is attached to the surface of thewindshield 904. On the one hand, the polarization multiplexingvolume hologram element 903 forms a virtual image outside thewindshield 904 by the incident light; on the other hand, the polarization multiplexingvolume hologram element 903 diffracts the incident light to the vicinity of the human eye to form a viewpoint.
Specifically, when the rotation angle of theadjustable polarizer 902 is 45 °, an image can be simultaneously displayed at two projection distances. The far virtual image can be viewed simultaneously from the viewpoint a at the driver and the viewpoint b at the co-driver. In the present embodiment, 45 ° is merely exemplary, and this angle may be any angle between 0 ° and 90 °.
The above embodiments can all be applied to color display by using the superposition of three-layer volume hologram elements.
The above description is only a preferred embodiment of the present application and is illustrative of the principles of the technology employed. It will be appreciated by those skilled in the art that the scope of the invention herein disclosed is not limited to the particular combination of features described above, but also encompasses other arrangements formed by any combination of the above features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.