Full color holographic projector with variable virtual image distance using single coherent light source

Abstract

Disclosed herein is a product that may include a light source, a wavelength conversion structure downstream of the light source, a spatial filter downstream of the wavelength conversion structure, and a spatial light modulator downstream of the spatial filter. Also disclosed herein is a method that may include transmitting a first light from a light source through a wavelength conversion structure to down-convert the first light to a first primary color light; transmitting the first primary color light through a spatial filter to convert the first primary color light into spatially coherent first primary color light; the spatially coherent first primary color light is transmitted through a spatial light modulator to convert the spatially coherent first primary color light into spatially and temporally enhanced first primary color light.

Description

Technical Field

[0001] The technical field generally relates to holographic projectors, compartments therefor, and methods of using the same. Background Art

[0002] A holographic projection is known as a picture generation unit comprising three lasers for full color and three spatial light modulators for holographic projection as well as corresponding optical components for each color channel.

[0003] It is desirable to provide a picture generation unit with reduced component count, weight, and cost.Furthermore, other desirable features and characteristics of the variations disclosed herein will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing disclosure. Summary of the Invention

[0004] A number of variations may include a product comprising a light source, a wavelength conversion structure downstream of the light source, a spatial filter downstream of the wavelength conversion structure, and a spatial light modulator downstream of the spatial filter.

[0005] Variations may include a product wherein the spatial filter includes a pinhole formed therein.

[0006] Variations may include a product wherein the spatial filter is constructed and arranged to adjust the size of the pinhole.

[0007] Variations may include a product wherein the pinholes have a diameter in the range of 500 microns to 100 microns.

[0008] Variations may include a product wherein the wavelength conversion structure includes at least one conversion material for selectively generating primary colors.

[0009] A number of variations may include a product wherein the wavelength conversion structure is constructed and arranged to enhance temporal coherence.

[0010] A number of variations may include a product wherein the spatial filter is constructed and arranged to enhance spatial coherence.

[0011] Variations may include a product wherein the wavelength conversion structure and the spatial light modulator are constructed and arranged to be driven at at least three times the speed of the video source.

[0012] Variations may include a product wherein the wavelength conversion structure includes phosphor materials capable of being excited to produce primary colors.

[0013] Variations may include a product wherein the wavelength conversion structure comprises quantum dots capable of being excited to produce primary colors.

[0014] Multiple variations may include a method comprising: sending first light from a light source through a wavelength conversion structure to down-convert the first light into first primary color light; sending the first primary color light through a spatial filter to convert the first primary color light into spatially coherent first primary color light; sending the spatially coherent first primary color light through a spatial light modulator to convert the spatially coherent first primary color light into spatially and temporally enhanced first primary color light.

[0015] Multiple variations may include a method further comprising: thereafter sending second light from the light source through a wavelength conversion structure to down-convert the second light into second primary color light; sending the second primary color light through a spatial filter to convert the second primary color light into spatially coherent second primary color light; sending the spatially coherent second primary color light through a spatial light modulator to convert the spatially coherent second primary color light into spatially and temporally enhanced second primary color light.

[0016] Multiple variations may include a method further comprising: thereafter sending a third light from the light source through a wavelength conversion structure to down-convert the third light into a third primary color light; sending the third primary color light through a spatial filter to convert the third primary color light into a spatially coherent third primary color light; sending the spatially coherent third primary color light through a spatial light modulator to convert the spatially coherent third primary color light into a spatially and temporally enhanced third primary color light.

[0017] Variations may include a method wherein the spatial filter comprises a pinhole formed therein.

[0018] Variations may include a method wherein the spatial filter comprises a pinhole formed therein, the pinhole having a diameter in the range of 500 microns to 100 microns.

[0019] Variations may include a method wherein the wavelength conversion structure comprises at least one conversion material for selectively generating primary colors.

[0020] Variations may include a method wherein the wavelength conversion structure is constructed and arranged to enhance temporal coherence.

[0021] Variations may include a method wherein a spatial filter is constructed and arranged to enhance spatial coherence.

[0022] Variations may include a method wherein the wavelength conversion structure and the spatial light modulator are driven at at least three times the speed of the video source.

[0023] Multiple variations may include a method comprising: generating a signal from a computer or computing device and sending the signal to a digital micromirror device or microelectromechanical system, thereby causing the digital micromirror device or microelectromechanical system to generate an image of a video frame; calculating a hologram of the image of the video frame in three color channels; determining a required laser pulse width for each color; moving a waveguide conversion structure to an area having a wavelength conversion material for green emission; addressing a spatial light modulator using the hologram for green and addressing the laser using the pulse width determined for green; moving the waveguide conversion structure to an area having a wavelength conversion material for red emission; addressing the spatial light modulator using the hologram for red and addressing the laser using the pulse width determined for red; moving the waveguide conversion structure to an area without wavelength conversion material; addressing the spatial light modulator using the hologram for blue and addressing the laser using the pulse width determined for blue. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Various variations will be described below with reference to the following drawings, wherein like reference numerals represent like elements, and wherein:

[0025] Figure 1 is a schematic diagram of a product according to a plurality of variations;

[0026] Figure 2 is a schematic diagram of a product including an image generator according to a number of variations;

[0027] Figure 3 Methods according to a number of variations are shown;

[0028] Figure 4 A product for generating a hologram in a head-up display including a vehicle according to a number of variations is shown;

[0029] Figure 5 A product comprising a pair of glasses for displaying a hologram according to a number of variations is shown; and

[0030] Figure 6 A product comprising a set of goggles for displaying a hologram is shown according to a number of variations;

[0031] Figure 7 is a flowchart illustrating a method according to a number of variations; and

[0032] Figure 8 is a flowchart illustrating a method according to a number of variations. DETAILED DESCRIPTION

[0033] The following detailed description is merely illustrative in nature and is not intended to limit the application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

[0034] Figures 1 to 2, which may include a product 100, which may be a holographic projector. Product 100 may include a light source 102 and a wavelength conversion structure 104 downstream of light source 102. As used herein, the term "downstream" refers to the direction in which light flows from light source 102. Light source 102 may be any of a variety of devices capable of generating light 101 at one or more wavelengths. In various variations, light source 102 may be a light source that generates light of a relatively short wavelength. In various variations, light source 102 may be a laser that emits blue light. Wavelength conversion structure 104 may be constructed and arranged to allow light to pass therethrough and may be movable to a first position such that light passing through first region 106 generates one of the primary colors, e.g., red; and may be movable to a second position such that light passing through second region 108 generates a second primary color, e.g., green; and may be movable to a third position such that light passing through third region 110 generates a third primary color, e.g., blue. Options for the coating material of the wavelength conversion structure include phosphors or quantum dots that can down-convert incident light and emit visible wavelengths. The wavelength conversion structure 104 can be a rotatable plate or disk having three regions 106, 108, and 110 defined therein, such that light passing through one of these regions produces or emits one of the primary colors. In various variations, the three regions 106, 108, and 110 of the rotatable plate or disk can be of equal size. However, the wavelength conversion structure 104 is not limited to a disk configuration and can take on a variety of shapes to provide three distinct regions coated with a material option that produces the three primary colors of red, green, and blue when light passes through the corresponding regions. For example, the wavelength conversion structure 104 can be three plates that extend radially from an axis and are rotatable, such that one of the plates produces or emits one of the primary colors. In another example, the wavelength conversion structure 104 can be a substrate in the form of a strip having three regions through which light can pass to produce the three primary colors of red, green, and blue. In various embodiments, wavelength conversion structure 104 can be coated with a phosphor material that can be excited by three different wavelengths to selectively produce a primary color when light passes through one of the regions. In various embodiments, wavelength conversion structure 104 can include quantum dots that can be selectively excited to produce a primary color when light passes through it. One example of a method for exciting the phosphor or quantum dots is to excite the electrons of the material using a light source with a peak wavelength that matches the photonic band gap of the material, where the peak wavelength is selected to be the wavelength of light source 102. The electrons are excited and move to the upper band. During the relaxation process, the electrons move to a lower energy level and emit light with a longer wavelength. Wavelength conversion structure 104 is designed to emit the three primary colors of red, green, and blue in different regions. If light source 102 is selected to be blue, two of the three regions are coated with quantum dots or phosphors that emit red and green, while one of the three regions is left uncoated.If the light source is chosen to be outside the visible wavelength, the three regions are coated with quantum dots that emit red, green, and blue in separate areas. The size of the quantum dots determines the emission wavelength because it controls the photonic band gap. The band gap of the phosphor is determined by its chemical structure. In various variations, the wavelength conversion structure 104 can be a narrowband filter to enhance the temporal coherence of the light.

[0035] Figure 2 , which may include an image generator 112, which may include, but is not limited to, a digital micromirror device (DMD) or a microelectromechanical system (MEMS). A DMD or MEMS may be a matrix or array of micromirrors that, by changing orientation, allows light to be diverted or reflected in a controlled manner to generate a pattern or image. The matrix or array of micromirrors may include more than one million micromirrors. The image generator 112 may be interposed between the light source 102 and the wavelength conversion structure 104. The image generator 112 may generate a plurality of frames, wherein each frame includes at least one object or image. The image generator 112 may generate the plurality of frames at a rate or speed (e.g., X Hz).

[0036] Downstream of the wavelength conversion structure 104 is a spatial filter 114. The spatial filter 114 can be a planar substrate having a pinhole 116 formed therethrough. In various variations, the pinhole 116 can be adjustable. In various variations, the pinhole 116 can have a diameter in the range of 500 μm (micrometers) to 100 μm. The pinhole 116 can be formed or adjusted to control the spatial coherence of light passing therethrough. The pinhole 116 can be adjusted manually during design and to determine the optimal spatial coherence, or electronically using a motorized iris.

[0037] The beam collimating optics 118 may be positioned downstream of the spatial filter 114. The beam collimating optics 118 may operate such that a beam of light passing therethrough maintains its size and shape over a long distance.

[0038] A spatial light modulator (SLM) 120 may be disposed downstream of the beam collimating optics 118. The SLM may be operable to control the intensity, phase, or polarization of light in a spatially varying manner.

[0039] The optical waveguide 122 may be positioned downstream of the SLM 120. Light entering the optical waveguide 122 may be guided a distance through the waveguide light and exit at a desired location.

[0040] In a number of variations, light exiting the optical waveguide 122 can be reflected by the transparent substrate 124 for observation by a human 126 or an electronic device, such as, but not limited to, an artificial intelligence computer or device for viewing and drawing inferences therefrom. In a number of variations, the transparent substrate 124 can comprise glass or another transparent material. In a number of variations, the transparent substrate 124 can be supported by a carrier 127. In a number of variations, the transparent substrate 124 is a windshield or window glass of a vehicle (carrier 127), such as, but not limited to, a car, truck, bus, motorcycle, airplane, ship, or any other mobile structure for transporting people or goods. In a number of variations, the transparent substrate 124 can be one or more lenses in a pair of smart glasses (carrier 127) or a set of goggles (carrier 127).

[0041] At least one special purpose computer 128 may be provided and may include an electronic processor 130 operatively connected to a non-transitory computer readable memory 132 having written instructions 134 stored thereon and executable by the electronic processor 130 to control, operate, or provide the functionality described herein. In various variations, the at least one special purpose computer 128 may be connected to and operatively control at least one of the light source 102, the image generator 112, the wavelength conversion structure 104, the spatial filter 114, the beam collimating optical system 118, and / or the spatial light modulator 120.

[0042] Figure 3, which may include a method for using product 100, which may be a holographic projector, to generate a full-color holographic image. Wavelength conversion structure 104 is driven at three times the rate at which image generator 112 generates frames including at least one object or image. During the time image generator 112 generates a frame, wavelength conversion structure 104 moves so that first region 106 is positioned so that if any light from light source 102 passes through it, green light will be generated. Thereafter, wavelength conversion structure 104 moves so that second region 108 is positioned so that if any light from light source 102 passes through it, blue light will be generated. Thereafter, wavelength conversion structure 104 moves so that third region 110 is positioned so that if any light from light source 102 passes through it, red light will be generated. For example, if an object or image, or a portion thereof, in a frame generated by image generator 112 appears yellow to a human observer, then during the duration of the frame, wavelength conversion structure 104 is rotated so that first region 106 is positioned so that light passing through first region 106 produces green light. Thereafter, wavelength conversion structure 104 is rotated so that second region 108 is positioned downstream of, but not emitting light from, light source 102, so that no blue light is produced. Thereafter, wavelength conversion structure 104 is rotated so that third region 110 is positioned so that light from light source 102 passing through it produces red light. Thus, during the duration of frame 136, green and red light are generated within a sufficiently short period of time so that a human observer perceives the object or image, or portion thereof, as yellow. For example, if a frame occurs at X Hz, SLM 120 and wavelength conversion structure 104 are driven at a rate of 3X Hz.

[0043] Figure 4 , wherein carrier 127 is a car and a human observer 126 drives the vehicle with his hands on a steering wheel 164. Product 100 generates a holographic image that can be reflected from mirror 166 to a transparent substrate 124, which can be the windshield of the vehicle, so that the human 126 driving the vehicle sees a holographic image 168, such as, but not limited to, an arrow showing the direction of the path the vehicle should take, which appears at a distance from the human 126 and carrier 127 (i.e., the vehicle).

[0044] Figure 5 The transparent substrate 124 is shown as a lens and the carrier 127 is shown as a frame of glasses to be worn by a human.

[0045] Figure 6 The transparent substrate 124 is shown as a lens and the carrier 127 is shown as a pair of goggles for a human to wear.

[0046] Figure 7Several variations are shown in FIG. , which may include a method comprising step 138 of sending a full-color video frame. For example, a signal is generated from a computer or computing device and sent to a DMD or MEMS, causing the DMD or MEMS to generate the video frame. Subsequently, in step 140, holograms of the image in the frame are calculated in three color channels. Subsequently, in step 142, the required pulse width for each color is determined. Subsequently, in step 144, the waveguide conversion structure is rotated or moved to an area containing down-conversion material for green emission. Subsequently, in step 146, the SLM is addressed using the hologram for green, and the laser is addressed using the pulse width determined for green. Subsequently, in step 148, the wavelength conversion structure is moved or rotated to an area containing down-conversion material for red emission. Subsequently, in step 150, the SLM is addressed using the hologram for red, and the laser is addressed using the pulse width determined for red. Thereafter, in step 160, the wavelength conversion structure is moved or rotated to a region without down conversion material.Thereafter, in step 162, the SLM is addressed with the hologram for the blue color and the laser is addressed with a pulse width determined for the blue color.

[0047] Figure 8 , which may include a method comprising, in step 170, sending first light from a light source through a wavelength conversion structure to down-convert the first light into first primary color light. Thereafter, in step 172, sending the first primary color light through a spatial filter to convert the first primary color light into spatially coherent first primary color light. Thereafter, in step 174, sending the spatially coherent first primary color light through a spatial light modulator to convert the spatially coherent first primary color light into spatially and temporally enhanced first primary color light.

[0048] Although at least one illustrative variation has been presented in the foregoing detailed description, it will be understood that there are a large number of variations. It will also be understood that the exemplary embodiment or exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. On the contrary, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiment or exemplary embodiments. It will be understood that various changes may be made to the function and arrangement of elements without departing from the scope of the present disclosure as set forth in the appended claims and their legal equivalents.

Claims

1. A product, comprising: A light source, a wavelength conversion structure downstream of the light source, a spatial filter downstream of the wavelength conversion structure, and a spatial light modulator downstream of the spatial filter.

2. The product of claim 1, wherein the spatial filter comprises a pinhole formed therein.

3. The product of claim 2, wherein the spatial filter is constructed and arranged to adjust the size of the pinhole.

4. The product of claim 2, wherein the pinholes have a diameter in the range of 500 microns to 100 microns.

5. The product of claim 1, wherein the wavelength conversion structure comprises at least one conversion material for selectively generating a primary color.

6. The product of claim 1, wherein the wavelength conversion structure is constructed and arranged to enhance temporal coherence.

7. The product of claim 1 , wherein the spatial filter is constructed and arranged to enhance spatial coherence.

8. The product of claim 1, wherein the wavelength conversion structure and the spatial light modulator are constructed and arranged to be driven at at least three times the speed of a video source.

9. The product of claim 1, wherein the wavelength conversion structure comprises a phosphor material capable of being excited to produce a primary color.

10. A method comprising: sending first light from a light source through a wavelength conversion structure to down-convert the first light into a first primary color light; sending the first primary color light through a spatial filter to convert the first primary color light into spatially coherent first primary color light; The spatially coherent first primary color light is sent through a spatial light modulator to convert the spatially coherent first primary color light into spatially and temporally enhanced first primary color light.

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