Holographic projection system

Abstract

A holographic projection system comprises: a light source configured to generate a first light beam; a spatial light modulator configured to receive the first light beam and project a second light beam; a diffuser configured to rotate and include a plurality of regions, two or more of the regions containing respective down-conversion materials, each of the respective down-conversion materials converting one color of the second light beam to a different color; and at least one control module configured to generate an image, encode the spatial light modulator with a plurality of holograms to generate the second light beam including instances of the image, and control the rotation of the diffuser to display and overlay the instances of the image to provide a resulting image.

Description

introduction

[0001] The information contained in this section serves to generally illustrate the context of the disclosure. The work of the inventors named herein, to the extent described in this section, as well as aspects of the description that were not prior art at the time of filing, are neither expressly nor implicitly acknowledged as prior art with respect to the present disclosure.

[0002] The present disclosure relates to holographic display systems for projection and head-up display systems for vehicles.

[0003] Display devices are used in a wide variety of applications. Some examples of display devices are flat panel displays, projection displays, and head-up displays. Display devices can be either transmissive or reflective.

[0004] A driver of a vehicle typically views the vehicle's surroundings through windows, windshields, and other glass of the vehicle. The driver can control the vehicle's acceleration, deceleration, and steering based on their visual observation of the vehicle's surroundings. The vehicle may be equipped with one or more displays that show various information to the driver. For example, some vehicles have an infotainment system that includes a display that shows various infotainment and other vehicle information. The vehicle may also have a head-up display (HUD), which displays information by creating a virtual image at a specific distance through reflection of the windshield. For example, the HUD can display vehicle speed and other vehicle information (e.g., warnings such as lane departure warnings and collision avoidance warnings).

[0005] US 2011 / 0 251 905 A1 discloses a touch-sensitive holographic display device for holographically projecting a touch-sensitive image at an acute angle onto a surface on which the device is placed. The device comprises holographic image projection optics with at least one coherent light source illuminating a spatial light modulator, output optics for projecting a hologram onto an acute-angled surface, and a remote touch sensing system.

[0006] In the document US 2016 / 0 118 265 A1 the use of a rotating diffuser in a path of collimated light is disclosed in order to reduce speckles associated with laser light and to reduce quantization error. Summary

[0007] A holographic projection system is disclosed and comprises: a light source configured to generate a first light beam; a spatial light modulator configured to receive the first light beam and project a second light beam; a diffuser configured to rotate and comprising a plurality of regions, two or more of the regions comprising respective down-conversion materials.down-conversion materials), and wherein each of the respective down-conversion materials converts one color of the second light beam to another color; and at least one control module configured to generate an image, encode the spatial light modulator with a plurality of holograms to generate the second light beam including instances of the image, and control rotation of the diffuser to display and overlay the instances of the image to provide a resulting image.

[0008] In other features, the control module is configured to rotate the diffuser at at least three times the frame rate of the image, such that the diffuser rotates once per repetition cycle of the image.

[0009] In other features, the image is displayed multiple times in multiple colors. The copies of the image are available in each color.

[0010] In other features, the diffuser includes a first region that transmits light of a first color. A second region converts light of the first color to a second color. A third region converts the light of the first color to a third color.

[0011] In other characteristics, the first color is blue. The second color is green. The third color is red.

[0012] According to the invention, the diffuser comprises: a first region containing no down-conversion material; a second region containing a first down-conversion material; and a third region containing a second down-conversion material different from the first down-conversion material.

[0013] In other features, the first downconversion material changes a wavelength of light of a first color to a second wavelength associated with light of a second color. The second downconversion material changes the wavelength of the light of the first color to a third wavelength associated with light of a third color.

[0014] In other features, the holographic projection system further includes a beam expander assembly configured to expand the first light beam before it is received at the spatial light modulator.

[0015] In other features, the holographic projection system further includes a relay optics assembly configured to collimate light from the spatial light modulator onto one of the regions of the diffuser.

[0016] In other features, the holographic projection system further comprises a motor configured to rotate the diffuser, wherein the at least one control module is configured to control operation of the motor such that the second light beam is directed at each of the regions at different time periods to display the instances of the image.

[0017] In other features, a holographic projection method is disclosed and comprises: generating a first light beam via a light source; receiving the first light beam at a spatial light modulator and projecting a second light beam via the spatial light modulator; rotating a diffuser, the diffuser comprising regions, two or more of the regions comprising respective down-conversion materials, and each of the respective down-conversion materials converting one color of the second light beam to a different color; generating an image; encoding the spatial light modulator with holograms to generate the second light beam including instances of the image; and controlling the rotation of the diffuser to display and overlay the instances of the image to provide a resulting image.

[0018] In other features, the holographic projection method further comprises: calculating the holograms; determining pulse widths for colors of the instances of the displayed image; addressing the spatial light modulator with a first hologram for green emission and addressing the light source with a first pulse width determined for green emission; addressing the spatial light modulator with a second hologram for red emission and addressing the light source with a second pulse width determined for red emission; and addressing the spatial light modulator with a third hologram for blue emission and addressing the light source with a third pulse width determined for blue emission.

[0019] In other features, the holographic projection method further comprises rotating the diffuser at at least three times the frame rate of the image such that the diffuser rotates once per repetition cycle of the image.

[0020] In other features, the image is displayed multiple times in multiple colors. The copies of the image are available in each color.

[0021] In other features, the diffuser includes a first region transmissive to light of a first color, a second region converting light of the first color to a second color, and a third region converting light of the first color to a third color.

[0022] In other characteristics, the first color is blue, the second color is green, and the third color is red.

[0023] According to the invention, the diffuser comprises: a first region containing no down-conversion material; a second region containing a first down-conversion material; and a third region containing a second down-conversion material different from the first down-conversion material.

[0024] In other features, the first downconversion material changes a wavelength of light of a first color to a second wavelength associated with light of a second color. The second downconversion material changes the wavelength of the light of the first color to a third wavelength associated with light of a third color.

[0025] In other features, the holographic projection method includes: expanding the first light beam before it is received at the spatial light modulator; and collimating light from the spatial light modulator onto one of the regions of the diffuser.

[0026] In other features, the holographic projection method further comprises rotating the diffuser so that the second light beam is directed at each of the regions at different time periods to display the instances of the image.

[0027] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are for illustrative purposes only and are not intended to limit the scope of the disclosure. Short description of the drawings

[0028] The present disclosure will be more fully understood from the detailed description and the accompanying drawings, in which: Fig. 1 is a functional block diagram of an exemplary holographic projection system including a laser, a spatial light modulator (SLM), and a rotating diffuser, according to the present disclosure; Fig. 2 is a functional block diagram of another exemplary projection system including a laser, an SLM, and a rotating diffuser, according to the present disclosure; Fig. 3 is a front view of a rotating diffuser according to the present disclosure; Fig. 4 is an example timing diagram illustrating laser timing and color emission for generating an example image according to the present disclosure; Fig. 5 is a functional block diagram of a vehicle incorporating a holographic projection system according to the present disclosure; Fig. 6 is a perspective view of an exemplary interior of a vehicle incorporating a HUD; and Fig. 7 illustrates an exemplary holographic projection method according to the present disclosure.

[0029] Reference numbers may be reused in the drawings to identify similar and / or identical elements. Detailed description

[0030] A vehicle may contain a holographic HUD comprising an SLM and a coherent or partially coherent light source. The phase hologram is encoded on an SLM. Light from a coherent or partially coherent light source illuminates the SLM, which is encoded with a phase hologram, and the light is diffracted in a manner prescribed by the hologram. The diffracted light is reflected from a vehicle windshield and forms a real image on the driver's retina.

[0031] Holographic display systems often use a source of coherent light, such as a laser, in conjunction with the other display components. Coherent light can refer to light that is spatially and temporally in phase. When coherent light reflects from a surface, different points on the surface are considered a single secondary light wave. When independent red, green, and blue (RGB) channels are used, such as in a 3-LCoS holographic HUD, three spatially aligned RGB images are provided in an eyebox. The eyebox can refer to a rectangular, flat area in which a viewer can see an image.

[0032] A holographic projection system (e.g., a holographic projection system of a multi-plane HUD) contains a componentry to produce holographic color projection. The componentry is expensive and may include three color channels, with each color channel comprising: a respective laser emitting a respective colored light beam (e.g., a red, green, or blue light beam); a respective SLM for hologram projection in the color of the corresponding light source; and corresponding optical components for that color channel.

[0033] The examples presented herein include utilizing a rotating diffuser with different regions containing different downconversion materials. The rotating diffuser includes multiple regions (e.g., three regions), each emitting light at a specific wavelength. The wavelength of the light emitted by each region differs from the wavelength of the light emitted by any other region. The incorporation of the rotating diffuser enables the generation of three different colored light beams using one laser and a single SLM instead of three lasers and three SLMs. As a result, the disclosed holographic projection systems have reduced SLM calibration complexity.

[0034] The disclosed embodiments feature novel optical designs to realize a full-color holographic projector (or full-color holographic projection system) with a single light source and a single SLM. This contrasts with a conventional projector that includes three light sources and three SLMs. By reducing the number of components, the disclosed holographic projection systems are lighter in weight, cost less, and require less space. Each of the disclosed full-color holographic projection systems may include a diffuser with regions containing various downconversion material layers. The downconversion material layers may include phosphor layers, quantum dot layers, and / or other downconversion material layers. The downconversion materials are further described below.A sequential timing controller is implemented to drive a fast-switching SLM in correlation with the rotation of the diffuser. The fast-switching SLM switches between multiple holograms for multiple colors to generate the image instances, which are superimposed to create a resulting image seen by a viewer.

[0035] Fig. 1 shows a holographic projection system 100 that includes a laser 102, an SLM 104, and a rotating diffuser 106. The laser 102 generates a light beam 108 having a first wavelength. As an example, the laser 102 may be a single-wavelength light source and generate a blue light beam having a wavelength of 445 nanometers (nm). Although a laser is depicted, any other type of light source may be used. The light beam 108 is directed toward a beam expander assembly 110, which may include beam expander optics. An expanded beam 112 is directed from the beam expander assembly 110 toward the SLM 104. The beam expander optics include lenses that expand the light beam 108 to create a beam to illuminate and mask an active area of ​​the SLM 104.

[0036] The SLM 104 is tuned to the color (e.g., blue) of the light generated by the laser 102. A display control module 114 encodes the SLM 104 with a hologram to display an image. The image may have the same color as the light generated by the laser 102. The SLM 104 is tuned to a wavelength of the laser 102 and / or light beam 108. Relay optics of a relay optics assembly 116 are arranged between the SLM 104 and the diffuser 106. The relay optics collimate light from the SLM 104 and focus an image onto a first region 120 of the diffuser 106.

[0037] The diffuser 106 is rotated, which is why it is referred to as a rotating diffuser. The diffuser 106 is rotated by a motor 122 controlled by the display control module 114. The rotation of the diffuser 106 is indicated by an arrow 123. The diffuser 106 comprises at least three regions (or zones), including the first region 120, a second region 124, and a third region 126. At least two of the regions have and may be coated with a down-conversion material layer. In the example shown, the area of ​​the front surface of the diffuser 106 is divided into three equal regions, and two of the three regions are coated with a respective down-conversion material, such as a phosphor, quantum dot, and / or other down-conversion material.In one embodiment, one of the three regions is clear and / or not coated with a downconversion material and is transparent to blue light. A second of the regions is coated with a first downconversion material to transmit green light. A third of the regions is coated with a second downconversion material to transmit red light. The downconversion materials can be coated in the regions, formed as layers over the regions, and / or integrated into materials of the regions. The second and third regions can be substrates doped with a downconversion material. Diffuser 106 scatters the received collimated light to emit non-collimated light. Diffuser 106 is highly efficiently transparent.

[0038] In one embodiment, the SLM 104 is encoded with a hologram and displays a blue object 128 (e.g., a blue arrow) on one of the regions (e.g., region 120) of the diffuser 106. The diffuser 106 is rotated at a high speed such that each of the regions 120, 124, 126 is aligned with the output of the relay optics assembly 116 at a rate of at least 30-60 times per second. Consequently, the diffuser 106 rotates at at least 30-60 revolutions per second. In one embodiment, blue light from the relay optics assembly 116 is transmitted through the first region 120 to display the blue object, excites green phosphor of the downconversion material layer in the second region 124 to display the object in green, and exits red phosphor of the downconversion material layer in the third region 126 to display the object in red.Laser 102 can be turned ON or OFF when one of regions 120, 124, 126 is aligned with the output of relay optics assembly 216. For example, if an image of a yellow arrow is to be generated, laser 102 can be turned OFF for region 120 and ON for regions 124 and 126, since a mixture of green and red light is yellow light.

[0039] The downconversion material of regions 124, 126 can consist of respective phosphor types that convert a received light beam with light at a first wavelength (e.g., blue light with a wavelength of 445 nm) into a second light beam with light at a second wavelength (e.g., green light with a wavelength of 520 nm) and a third light beam with light at a third wavelength (e.g., red light with a wavelength of 627 nm). The image of the object can be displayed in any color, since any color can be generated with various combinations of RGB illumination. This can be achieved by adjusting, when the laser is turned ON with respect to the rotational position of the diffuser 106, the holograms with which the SLM 104 is addressed for regions 120, 124, 126, the luminance of light from the relay optics assembly 116, etc.The luminance can be adjusted by adjusting the pulse width of the light beam 108 from the laser 102 and / or the grayscale of a graphic being displayed. The grayscale of the displayed image can be adjusted using the display control module 114.

[0040] The image and / or object (e.g., object 128) being displayed is projected by diffuser 106 onto a screen 130. The image and / or object displayed on the screen is designated 132.

[0041] Fig. Figure 2 shows a holographic projection system 200 comprising a laser 202, a spatial light modulator (SLM) 204, and a rotating diffuser 206. The holographic projection system 200 is similar to the holographic projection system 100 of Fig. 1, except that the image is reflected from a windshield or other reflector 210 and seen by the eyes of the viewer (one eye 212 is shown).

[0042] Laser 202 generates a light beam 208 having a first wavelength. Light beam 208 is directed to a beam expander assembly 211, which may include beam expander optics. An expanded beam 213 is directed from beam expander assembly 211 to SLM 204. The beam expander optics include lenses that expand light beam 208 to provide a beam that illuminates and covers an active area of ​​SLM 204.

[0043] The SLM 204 is tuned to the color (e.g., blue) of the light generated by the laser 202. A display control module 214 encodes the SLM 204 with a hologram to display an image. The image may have the same color as the light generated by the laser 202. The SLM 204 is tuned to a wavelength of the laser 202 and / or the light beam 108. Relay optics of a relay optics assembly 216 are arranged between the SLM 204 and the diffuser 206. The relay optics collimate light from the SLM 204 and focus an image onto a first region 220 of the diffuser 206.

[0044] The diffuser 206 is rotated by a motor 222 controlled by the display control module 214. The rotation of the diffuser 206 is indicated by an arrow 223. The diffuser 206 includes at least three regions, including the first region 220, a second region 224, and a third region 226. At least two of the regions contain and may be coated with a downconversion material layer, such as one of the downconversion materials referred to herein. The diffuser 206 scatters the received collimated light to emit uncollimated light.

[0045] In one embodiment, the SLM 204 is encoded with a hologram and displays a blue object 228 (e.g., a blue arrow) on one of the regions (e.g., region 120) of the diffuser 206. The diffuser 206 is rotated at high speed so that each of the regions 220, 224, 226 is aligned with the output of the relay optics assembly 116 at a rate of at least 30-60 times per second. Thus, the diffuser 206 rotates at at least 30-60 revolutions per second. The laser 202 can be turned ON or OFF when one of the regions 220, 224, 226 is aligned with the output of the relay optics assembly 216.

[0046] The downconversion material of regions 224, 226 can consist of respective phosphor types that convert a received light beam with a first wavelength (e.g., blue light with a wavelength of 445 nm) into a second light beam with a second wavelength (e.g., green light with a wavelength of 520 nm) and a third light beam with a third wavelength (e.g., red light with a wavelength of 627 nm). The image of the object can be displayed in any color, since any color can be generated with various combinations of RGB illumination. This can be achieved by adjusting, when the laser is turned ON with respect to the rotational position of the diffuser 206, the holograms used to address the SLM 204 for regions 220, 224, 226, the luminance of light from the relay optics assembly 216, etc.The luminance can be adjusted by adjusting the pulse width of the light beam 208 from the laser 202 and / or the grayscale of the graphic being displayed. The grayscale of the image being displayed can be adjusted by the display control module 214.

[0047] The image and / or object (e.g., object 228) being displayed is projected from diffuser 206 onto reflector 210. In one embodiment, reflector 210 is a windshield of a vehicle. In another embodiment, the reflector is a mirror. In another embodiment, a plurality of reflectors are disposed between diffuser 206 and the viewer. In one embodiment, the plurality of reflectors includes one or more reflectors and a windshield. The one or more reflectors may include one or more mirrors. In another embodiment, no mirrors are included. SLM 204 is encoded with a graphic hologram via display control module 214 and provides a projected beam 240 that is directed through relay optics assembly 216 and onto diffuser 206.The light emitted by diffuser 206 is reflected by reflector 210 and viewed by a retina 242 of the viewer's eye 212. The display control module 214 may include display drivers for controlling the states of the SLM 204. An exemplary edge of an eyebox 246 is shown. The eyebox encompasses the range of locations on the eye 212 in which the image can be viewed by the viewer (or driver).

[0048] Fig. Figure 3 shows a rotating diffuser 300 that is evenly divided into several regions. In the example shown, the diffuser 300 comprises three regions 302, 304, 306. Region 302 is not coated with downconversion material. Regions 304, 306 are coated with downconversion material. The diffuser 300 comprises a shaft 308 that is connected to a shaft of a motor (e.g., one of the motors 122, 222 of the Fig. 1-2). The down-conversion material of region 304 differs from the down-conversion material of region 306. The down-conversion materials of regions 304 and 306 may include different types of phosphor material (e.g., inorganic phosphors such as strontium, barium, calcium, europium, yttrium, etc.), different types of quantum dot material, etc. The down-conversion materials of regions 304 and 306 excite different color light.

[0049] Fig. Figure 4 shows a timing diagram illustrating laser timing and color emission for generating an example image. Frames 400, 402, 404, 406 are shown, with corresponding rotational positions of a diffuser 408 and states of a laser 410. In the example shown, an image of a yellow arrow is displayed. To display a yellow arrow, a green arrow and a red arrow are displayed and overlapped to generate the yellow arrow. The holographic display projector switches from displaying no arrow to displaying the green arrow, to displaying the red arrow, and repeats this process at a high refresh rate so that the human eye sees only the yellow arrow.

[0050] During frames 400, 404, and 406, the laser 410 is turned on, generating a light beam that is passed through an expanding optical assembly 414 and directed to an SLM 416. The SLM 416 is encoded with a hologram to display an image of the object, which is projected onto a portion of the diffuser 408 via relay optics 418. Frame 400 is associated with displaying the arrow in a first color (e.g., green). In one embodiment, the blue light from the laser 410 is directed onto a first portion of the diffuser 408 coated with a first downconversion material to display the arrow in the first color. Frame 402 is associated with nothing being displayed (i.e., the laser 410 is off). The laser 410 is turned OFF, and thus no light is generated and passed through the second region of the diffuser 408. The frame 404 is associated with displaying the arrow in a second color (e.g., red).In one embodiment, the blue light of laser 410 is directed onto a third region of diffuser 408 coated with a second downconversion material to display the arrow in the second color. Frame 406 is again associated with displaying the arrow in the first color (e.g., green), as described for frame 400. This provides a time-sequential approach to displaying one or more objects in a selected color. If a display control module (e.g., one of the display control modules disclosed herein) sends a color graphic at X Hertz (Hz), SLM 416 and rotating diffuser 408 are driven at 3X Hz for time-sequential color generation, where X is a positive real number. The luminance of the image displayed can be adjusted by changing the pulse width of the generated laser light beam and / or by adjusting the grayscale value of the graphic image on the display control module.The grayscale value can be an eight-bit value between 0 - 255.

[0051] Fig. 5 shows a vehicle 500 including a holographic projection system 502. The holographic projection system 502 includes a vehicle control module 504, a display control module 506, sensors 508, a diffuser motor 510, a power source 512, a laser 514, and an SLM 516. The vehicle control module 504 can determine images to be displayed via the display control module 506. The sensors 508 can include exterior sensors for detecting objects and interior sensors such as cameras, radar sensors, lidar sensors, ultrasonic sensors, etc. The exterior sensors can detect vehicles, pedestrians, cyclists, buildings, etc. The interior sensors can be used to detect, for example, the positions and viewing angles of the viewer's eyes. The control modules 504, 506 can determine where an object is to be displayed, which display orDisplay locations should be colored, in which color the respective display location should be illuminated, which luminescence level should be set for the respective display location, etc. These specifications are based on outputs from the 508 sensors.

[0052] The power source 512 provides power to the control modules 504, 506, the diffuser motor 510, and the laser 514. The display control module 506 controls the operation of the diffuser motor 510 and the laser 514. The control modules 504, 506 can be implemented as a single module.

[0053] Fig. 6 shows an example interior of a vehicle 600 that includes a HUD 602. The vehicle 600 includes a windshield 604 located in a front opening of the vehicle 600. Passengers in a passenger cabin 608 of the vehicle 600 can look through the windshield 604 to see in front of the vehicle 600. Although the example of a land vehicle is described, the present application is also applicable to airborne vehicles (e.g., airplanes, helicopters, etc.) and waterborne vehicles (e.g., boats, etc.). Although some examples are disclosed herein with respect to vehicle implementations, the examples are also applicable to non-vehicle implementations. The windshield 604 is visually located above an instrument panel 606 of the vehicle 600. The vehicle 600 may include a steering wheel 610. The vehicle 600 may be an autonomous vehicle, a semi-autonomous vehicle, or a non-autonomous vehicle.

[0054] A holographic projection system, such as the one described above with respect to the Fig. 1-5, projects an image through an opening 616 in the instrument panel 606 onto a portion of the windshield 604. The image includes various vehicle information, such as a current speed of the vehicle 600, a current gear of a transmission of the vehicle 600, an engine speed, a direction of travel of the vehicle 600, current settings of the infotainment system, and / or other vehicle information. The image presents data to the driver of the vehicle without requiring the driver to look away from objects in front of the vehicle. As further discussed below, the image includes overlapping images of different colors that are the same size and spatially aligned to provide a single image seen by the viewer, as described herein.

[0055] Fig. 7 shows a holographic projection method. The operations may be performed iteratively. At 700, a vehicle control module (e.g., the vehicle control module 504 of Fig. 5) a full-color frame containing an image and sends it to a display control module (e.g., one of the display control modules 114, 214, 506 of the Fig. 1-2 and 5).

[0056] At 702, the display control module calculates the holograms for instances of an image to be displayed. In one embodiment, this is performed for three channels corresponding to three different regions of a rotating diffuser, as described above.

[0057] At 704, the display control module determines a pulse width for each color of the displayed instances. For example, the display control module determines a pulse width (or duty cycle) for each of the three colors of each of the three instances displayed to display a resulting image. The colors and instances have different pulse widths (or duty cycles). The image may be displayed in respective frames in each of the colors to provide the resulting image, as described above.

[0058] At 706, the display control module rotates a diffuser (e.g., one of the diffusers 106, 206, 300, 408 of the Fig. 1-4) to a first region with a green emission downconversion material. At 708, the display control module addresses an SLM (e.g., one of the SLMs 104, 204, 416 of the Fig.1-2 and 4) with a first hologram for green emission and addresses the laser with a pulse width determined for green emission.

[0059] At 710, the display control module rotates a diffuser to a second region containing a downconversion material for red emission. At 712, the display control module addresses an SLM with a second hologram for green emission and addresses the laser with a pulse width determined for red emission.

[0060] At 714, the display control module rotates a diffuser to a third region with a downconversion material for blue emission. At 716, the display control module addresses an SLM with a third hologram for green emission and addresses the laser with a pulse width determined for blue emission.

[0061] The operations described above are intended as illustrative examples. Depending on the application, the operations may be performed sequentially, synchronously, concurrently, continuously, during overlapping periods, or in a different order. Depending on the implementation and / or sequence of events, one of the operations may not be performed or may be skipped.

[0062] The examples disclosed herein include a full-color holographic projector with a single light source producing a single beam of short-wavelength light (e.g., blue light with a wavelength of 445 nm). The full-color holographic projector also includes a single SLM, relay optics, and a rotating diffuser coated with downconversion materials. The downconversion materials are excited by the light emitted by the single light source and emit light at visible wavelengths (e.g., red and green). The diffuser is coated with the downconversion materials and, along with the SLM, is driven at at least three times the frame and / or refresh rate of a video source (e.g., a display control module). The full-color holographic projector utilizes time-sequential hologram encoding of the SLM and time-sequential rotation of the diffuser to produce full color.

[0063] The foregoing description is merely illustrative in nature and is intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure may be embodied in a variety of forms. Therefore, while this disclosure contains specific examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure.Furthermore, although each of the embodiments is described above as having certain features, one or more of those features described with respect to any embodiment of the disclosure may be implemented in one of the other embodiments and / or combined with features of one of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with each other remain within the scope of this disclosure.

[0064] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "near," "on," "above," "below," and "disposed." Unless explicitly described as "direct," when a relationship between first and second elements is described in the above disclosure, that relationship may be a direct relationship, with no other intervening elements present between the first and second elements, but may also be an indirect relationship, with one or more intervening elements (either spatial or functional) present between the first and second elements.As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logical (A OR B OR C) using a non-exclusive logical OR, and should not be construed to mean "at least one of A, at least one of B, and at least one of C."

[0065] In the figures, the direction of an arrow, as indicated by the arrowhead, generally illustrates the flow of information (e.g., data or instructions) of interest to the illustration. For example, if element A and element B exchange a lot of information, but information transmitted from element A to element B is important to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Moreover, for information transmitted from element A to element B, element B may send requests for, or acknowledgments of receipt of, the information to element A.

[0066] Throughout this application, including the definitions below, the term "module" or "controller" may be replaced by the term "circuit." "The term "module" may refer to, be part of, or include an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field-programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) executing code; a memory circuit (shared, dedicated, or group) storing code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above components, such as in a system-on-chip.

[0067] The module may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules connected via interface circuits. For example, multiple modules may enable load balancing. In another example, a server module (also known as a remote or cloud module) may perform some functions for a client module.

[0068] The term code, as used above, may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects. The term shared processor circuitry includes a single processor circuit that executes some or all of the code from multiple modules. The term group processor circuitry includes a processor circuit that, in combination with additional processor circuitry, executes some or all of the code from one or more modules. References to multiple processor circuits include multiple processor circuits on individual chips, multiple processor circuits on a single chip, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or any combination of the above.The term shared memory circuit refers to a single memory circuit that stores some or all of the code from multiple modules. The term group memory circuit refers to a memory circuit that, in combination with additional memories, stores some or all of the code from one or more modules.

[0069] The term "memory circuit" is a subset of the term "computer-readable medium." As used herein, the term "computer-readable medium" does not include transitory electrical or electromagnetic signals propagating through a medium (such as a carrier wave); therefore, the term "computer-readable medium" can be considered tangible and non-transitory.Non-limiting examples of a non-transitory, tangible computer-readable medium include non-volatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

[0070] The devices and methods described in this application may be implemented, in part or in whole, by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications that can be translated into computer programs through the routine work of a person skilled in the art or programmer.

[0071] The computer programs contain processor-executable instructions stored on at least one non-transitory, tangible, computer-readable medium. The computer programs may also contain or rely on stored data. The computer programs may include a basic input / output system (BIOS) that interacts with the computer's special-purpose hardware, device drivers that interact with specific special-purpose devices of the computer, one or more operating systems, user applications, background services, background applications, etc.

[0072] The computer programs may contain: (i) a description text to be analyzed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language) or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated from the source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. By way of example only, source code may be written using syntax from languages ​​including C, C++, C#, ObjectiveC, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, JavaScript®, HTML5 (Hypertext Markup Language 5th Revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK and Python®.

Claims

[1] Holographic projection system (100, 200, 502), comprising: a light source (102, 202, 410, 514) configured to generate a first light beam (108, 208); a spatial light modulator (104, 204, 416, 516) configured to receive the first light beam (108, 208) and project a second light beam; a diffuser (106, 206, 300, 408) configured to rotate and comprising a plurality of regions (120, 124, 126, 220, 224, 226, 302, 304, 306), wherein two or more of the plurality of regions (120, 124, 126, 220, 224, 226, 302, 304, 306) comprise respective down-conversion materials, and wherein each of the respective down-conversion materials converts one color of the second light beam to another color; and at least one control module (114, 214, 504, 506) configured to generate an image, encode the spatial light modulator (104, 204, 416, 516) with a plurality of holograms to generate the second light beam including a plurality of instances of the image, and control rotation of the diffuser (106, 206, 300, 408) to display and overlay the plurality of instances of the image to provide a resulting image; wherein the diffuser (106, 206, 300, 408) comprises: a first region (120, 220) containing no downconversion material; a second region (124, 224) containing a first downconversion material; and a third region (126,226) containing a second downconversion material different from the first downconversion material. [2] The holographic projection system (100, 200, 502) of claim 1, wherein the control module (114, 214, 504, 506) is configured to rotate the diffuser (106, 206, 300, 408) at at least three times the frame rate of the image, such that the diffuser (106, 206, 300, 408) rotates once per repetition cycle of the image. [3] Holographic projection system (100, 200, 502) according to claim 1, wherein: the image is displayed a multitude of times in a multitude of colours; and the multitude of copies of the image are each available in the multitude of colors. [4] Holographic projection system (100, 200, 502) according to claim 1, wherein: the diffuser (106, 206, 300, 408) comprises a first region (120, 220) that is transparent to light of a first color; a second region (124, 224) that converts light of the first color into a second color; and a third region (126, 226) which converts light of the first color into a third color. [5] Holographic projection system (100, 200, 502) according to claim 4, wherein: the first color is blue; the second color is green; and the third color is red. [6] Holographic projection system (100, 200, 502) according to claim 1, wherein: the first down-conversion material changes a wavelength of light of a first color to a second wavelength associated with light of a second color; and the second down-conversion material changes the wavelength of the light of the first color to a third wavelength associated with light of a third color. [7] The holographic projection system (100, 200, 502) of claim 1, further comprising a beam expander assembly (110, 211) configured to expand the first light beam (108, 208) before it is received at the spatial light modulator (104, 204, 416, 516). [8] The holographic projection system (100, 200, 502) of claim 1, further comprising a relay optics assembly (418) configured to collimate light from the spatial light modulator (104, 204, 416, 516) onto one of the plurality of regions (120, 124, 126, 220, 224, 226, 302, 304, 306) of the diffuser (106, 206, 300, 408). [9] The holographic projection system (100, 200, 502) of claim 1, further comprising a motor (122, 222, 510) configured to rotate the diffuser (106, 206, 300, 408), wherein the at least one control module (114, 214, 504, 506) is configured to control operation of the motor (122, 222, 510) to direct the second light beam at different time periods onto each of the plurality of regions (120, 124, 126, 220, 224, 226, 302, 304, 306) to display the plurality of instances of the image.

Images