RU2817180C1 - Device for forming multi-aspect three-dimensional (3d) image of projection type - Google Patents

Abstract

FIELD: imaging devices.

SUBSTANCE: invention relates to devices for forming a multi-aspect image of a projection type. Device comprises at least one projector configured to form an image in a corresponding viewing area, wherein each of the at least one projector is spaced from the geometric centre of the corresponding viewing area in the vertical plane relative to the eyes of the viewer and is located outside the corresponding viewing area, screen unit, having a scattering spatial distribution function and/or a reflection spatial distribution function, and configured to form at least one viewing area of the formed image. Screen unit has a retroreflector, an optical light-diffusing element, a redirecting optical element and a compensation unit, which are optically coupled with at least one projector and with at least one observer pupil.

EFFECT: invention provides higher contrast and image quality.

27 cl, 38 dwg

Description

Technical field

The invention relates to projection-type devices for generating a multi-view three-dimensional (3D) image, for example, an autostereoscopic or holographic image for one or more users, and can be used for educational, advertising and entertainment purposes at home, as well as in public places, such as cinemas , museums, educational institutions where there is a need to generate large holographic images.

Description of the Prior Art

There are a variety of imaging tools in the art that provide multi-view stereoscopic 3D images in a defined viewing area, both with viewing aids such as stereo glasses and without wearable devices, to maximize the viewer's sense of immersion.

However, known stereoscopic imaging devices have some limitations for obtaining high-quality 3D images.

The objective of the claimed invention is to solve the following problems of holographic/autostereoscopic imaging devices known from the prior art.

Low contrast of the generated image and low screen efficiency (Fig. 1A, 1B, 1C)

It is known to those skilled in the art that to comfortably view a high quality 3D image (holographic/autostereoscopic 3D image), the viewing area must be large enough across the screen vertical, e.g. ≥20 degrees, and with low screen dispersion, e.g. ≤1 degree, to eliminate overlap of viewing areas/crosstalk of viewing areas formed for each eye, and provide high image contrast, without ghosting while maintaining high efficiency of the generated image, i.e. the amount of light falling from the projector into the viewing area being formed, for example ≥50%.

Reflective films known in the art include, for example, reflective films based on glass beads, reflective films (see FIG. 1A) that use glass beads or spherical lenses as reflective elements, and reflective films that use reflective microprisms as reflective elements. (see Fig. 1B). Light in such reflective (retro-reflective) films undergoes scattering at the interface between materials and at defects in the volume (inside) of the material caused by technological errors, which causes very high scattering of radiation at the exit from the film, which makes it impossible to qualitatively separate the viewing areas of each eye for the formation 3D images.

In addition, when trying to expand viewing areas in the vertical direction using a diffuser (optical light-scattering element) that scatters radiation in the vertical direction, the 3D image resolution of conventional reflectors deteriorates.

Thus, in 3D image forming devices known from the prior art, there is very often overlap between the viewing zones for the right eye (R) and the left eye (L) of the observer (1), which causes ghosting and deterioration of the contrast of the 3D image (see Fig. 1C ).

Low vertical efficiency of the screen in the useful viewing area without the use of stereo glasses (Fig. 2A)

Devices known from the prior art for generating 3D images in a configuration in which the projector (2) is not fixed above the head of the observer (1), i.e. placed at a distance from the observer's head (1) and stereo glasses are not used, they have significant light scattering in the vertical direction of the viewing area. Therefore, part of the light in the vertical direction does not fall into the useful viewing area, while the viewing area for the observer’s left eye is designated as L, and for the right eye as R, and the screen consisting of a retroreflector is designated as position 3. This device configuration has low vertical efficiency , see Fig.2a.

Distortion of viewing areas with a wide field of view (FOV) (Fig. 2B)

If it is necessary to form a 3D image on a large screen (3), when the projector (2) is not fixed above the observer’s head (1), but is located at a distance from it, and stereo glasses are not provided in the configuration of the 3D image forming device, this leads to distortion (curvature) of the viewing area, with the viewing area for the left eye of the observer designated as L, and for the right eye as R. Due to this aberration, the viewing area becomes blurry/curved in the horizontal direction, and part of the field of view does not fall into the observer's pupil 1. Thus, only part of the entire image can be seen (see Fig. 2B).

An autostereoscopic three-dimensional (3D) display system with a retroreflective screen is known from the prior art (see US 8,328,360B2, IPC G03B 21/00, publ. 12/11/2012). In this case, display screens are characterized by a light-scattering and retroreflective effect. According to embodiments of an autostereoscopic 3D display system, a retroreflective and light-diffusing screen may be used to create a 3D autostereoscopic display by creating multiple viewports, where each viewport displays a unique perspective view of the image. The disadvantages of this system are that the system operates only with a centered (axial) configuration of projectors (projectors are located in the viewing area) and viewing aids, for example, glasses. This configuration requires the projectors to be fixed close to the viewer's head and/or the need to use additional wearable viewing devices, which causes inconvenience for the user. Moving projectors away from the user's head causes a loss in the efficiency of the generated 3D image.

In patent application US 2016/0277725A1, IPC H04N 13/04, publ. 09/22/2016 discloses a projected head-mounted display system that projects images onto a reflective screen, which are then reflected back for viewing by the user. The projected head-mounted display system displays computer-generated images at multiple focal lengths, simulating the light field and matching eye accommodation to vergence. The disadvantages of this system are the need to use additional viewing devices, for example, glasses, or in the presence of a fixed projection system on the user's head.

From the prior art, see CN110286495A, IPC G02B 27/22, publ.09/27/2019, a retroreflective stereoscopic display device based on a matrix of light sources is known. The display device consists of a light source array, a cylindrical lens array, a retroreflective film, and a liquid crystal (LCD) display panel. An array of light sources, a cylindrical lens array, and a reflective film are used to control the direction of light propagation in the device. Light emitted by any light source in the light source array may be reflected by the retroreflective film after passing through the LCD display panel and the cylindrical lens array, and may be reconverged into a vertical projection region where the light source is located. The LCD display panel provides an image parallax corresponding to the spatial position of the light source when turning on a specific light source in the light source matrix to form an observation area within the vertical projection area of the current light source. The light sources in the light source array are turned on in turn in a time division multiplexing mode, and the LCD display panel provides an image parallax corresponding to the light source, so that a plurality of observation areas can be formed in space, and the image parallax corresponds to the light source so that it can be seen , when a person's eyes are in different viewing areas, and thus a stereoscopic image can be created. The disadvantages of a retroreflective stereoscopic device is that it operates when the projector and observer are close together, which is due to the use of a matrix of corner reflectors in the device. This device is not user-friendly because it requires the use of additional viewing aids, such as glasses, or the need to fix the projector near the user's head.

Patent application US 20070146842A, published July 28, 2007, IPC GO2B 3/32, discloses a holographic projection screen, a method and system for its manufacture. A holographic projection screen includes a screen body on which an array of holographic lenses is located, said lenses being evenly spaced vertically and horizontally on the screen body adjacent to each other. Holographic lenses are round or elliptical, or have a regular polygonal shape. The holographic lens may be a collection of lenses. A method for manufacturing a holographic projection screen includes the following steps: 1) recording information about the holographic lens on a plate with photoresist; 2) metallization of the exposed wafer with a photoresist to produce a nickel master wafer of a holographic lens array through the electroforming and recombination method; 3) using the above master plate to emboss thermoplastic material to obtain the screen body.

The disadvantages of a holographic projection screen are the low efficiency of a 3D color image when using a microlens RGB HOE array. Possible ghost images caused by residual zero order diffraction when passing through the HOE.

In patent application US20010040717A1, publ. 11/15/2001, IPC G02B 5/00, describes a reflective display device including a switching layer disposed between substrates for switching between a transmitting state for transmitting incident light and a diffuse state for scattering incident light, and a retroreflector for reflecting incident light. beam from the liquid crystal layer so that the outgoing beam of reflected light is parallel to the incident beam. The retroreflector is preferably an array of cubic corner reflectors and has light-absorbing surface areas at the boundaries of the smallest structural elements.

The disadvantages of a reflective display device are: the use of a dielectric retroreflector in the device, the light in such retroreflectors undergoes many reflections and refractions, which causes very high radiation dispersion at the output of the reflector, and it is difficult to avoid overlapping viewing areas, crosstalk and poor 3D image quality.

The closest analogue (prototype) of the claimed invention is the solution disclosed in patent US 9182524B2, IPC G02B 30/27, publ.11/10/2015, which describes an autostereoscopic device for providing the viewer with a three-dimensional image in different vertical eye positions. The device includes a projection screen with a light-receiving surface that is reflective horizontally and light-scattering vertically. The projection screen of an autostereoscopic device can have various implementation options. For example, a projection screen may include a bottom layer including a retroreflective film that is retroreflective in at least a horizontal direction and a top layer made of a transparent sheet of lenticular material configured to diffuse light in a vertical direction.

The disadvantages of the device are significant scattering of radiation caused by the use of a transparent retroreflective film made of dielectric with many total internal reflection (TIR) prisms and light guides. The known autostereoscopic device is characterized by a small vertical field of view (FoV) and low image contrast (optical correctors are not provided in the device).

In addition, the authors of the invention conducted studies of the specific characteristics of the flagship solutions known on the market, as well as the claimed solution, which clearly demonstrate the advantage of the claimed device for forming a multi-angle 3D projection-type image.

In this case, the following were selected as the main characteristics: 1) approaches, 2) the presence of auxiliary means of observation (stereo glasses), 3) the possibility of vertical separation of the projector from the observer’s head, 4) efficiency in the viewing area, 5) field of view.

The claimed invention is characterized by the following:

1) the device contains: a highly efficient one-dimensional retroreflector, an optical light-scattering element, a redirecting element and a compensation unit,

2) observation aids, such as glasses, are not used

3) the possibility of a large vertical separation of the projector from the observer’s head is possible (up to <85 degrees in angular measure),

4) high efficiency of the device,

5) large field of view, for example, 40, 60, 120, etc. degrees.

Patent application US 2016/0277725 A1, patentee CastAR, Inc., Palo Alto, CA (US), “Light Field Reflective Display”:

1) the device includes: 2D reflector, stereo glasses,

2) stereo glasses are used,

3) no,

4) high efficiency of the device,

5) large field of view, due to the use of stereo glasses.

US Patent 9182524B2, Disney Enterprises, "One-Dimensional Retroreflector Autostereoscopic Display System":

1) the device contains: 1D retroreflector, optical light-scattering element,

2) stereo glasses are not used,

3) small, since the system does not provide for the separation of the projector from the user’s head, but since stereo glasses are not used, slight movement of the user’s head is allowed,

4) low efficiency of the device,

5) small field of view

Patent US008328360B2, Patentee Seiko Epson Corp., "Autostereoscopic 3D reflective display system":

1) the device contains: 2D retroreflector, optical light-scattering element,

2) it is possible to use stereo glasses, but it is also possible without glasses,

3) no,

4) high efficiency of the device,

5) small field of view

The presented analysis of the characteristics of 3D image forming devices known on the market clearly demonstrates the advantages of the claimed projection-type 3D image forming device.

The claimed invention relates to a projection-type device for forming a multi-angle color autostereoscopic/holographic 3D image, where a holographic/autostereoscopic scene/image is formed without the use of additional wearable devices by creating one or more viewing areas (windows) using at least two projectors to form an autostereoscopic image or at least one projector to form a holographic image and a new controlled/directional scattering screen.

In this case, the claimed invention provides the following advantages compared to the prior art:

- the ability to observe an autostereoscopic/holographic 3D image without the use of auxiliary observation equipment, for example, stereo glasses;

- formation of narrow and separate viewing areas provided by reduced diffusion/dispersion horizontally of the screen to prevent ghosting and deterioration of 3D image contrast;

- correction/minimization of manufacturing defects of the reflector;

- the ability to control/limit diffusion/scattering along the vertical screen;

- the ability to correct distortions in the viewing area.

Thus, the object of the claimed invention is to provide a multi-view 3D imaging device that provides a multi-view 3D image in a specific viewing area without the use of additional wearable devices to maximize the viewer's immersive experience. A screen unit is proposed that is capable of spatial control of the BRDF/BSDF (two-beam scattering function (BSDF) and/or two-beam reflectivity function (BRDF)), and is also capable of highly efficiently forming aberration-free viewing zones of the projected 3D image.

The essence of the invention

According to an aspect of the invention, a multi-view three-dimensional (3D) projection-type image generating device is provided, comprising:

at least one projector configured to form an image in a corresponding viewing area, wherein each of the at least one projector is spaced from the geometric center of the corresponding viewing area in a vertical plane relative to the eyes of the observer, and is located outside the corresponding viewing area,

a screen unit having a spatial distribution function of scattering and/or a spatial distribution function of reflection, and configured to form at least one viewing area of the generated image,

wherein the screen block contains a retroreflector, an optical light-scattering element, a redirecting optical element and a compensation block, optically coupled with at least one projector and with at least one pupil of the observer's eye,

the retroreflector is a reflective film made in the form of a set of one-dimensional rectangular prisms elongated in the vertical direction relative to the eyes of the observer with a reflective coating on the faces of the prisms,

an optical light-scattering element is located next to the retroreflector along the direction of radiation emitted from at least one projector, and is configured to scatter light reflected from the retroreflector in a vertical direction relative to the eyes of the observer,

the redirecting optical element has a spatial scattering distribution function and/or a spatial reflection distribution function, and is configured to redirect radiation, when reflected from the retroreflector and passing through the optical light-scattering element, to the area of at least one viewing zone in which the observer's eye is located when in use devices,

wherein said redirecting optical element is made with an offset optical axis relative to the optical axis of the device, and is characterized by zero optical power in the horizontal direction and a preset optical power (OP) in the vertical direction relative to the eyes of the observer, which is inversely proportional to the distance from the screen unit to the at least one corresponding viewing area,

the compensation unit is configured to compensate for distortion of at least one corresponding viewing area in the horizontal direction,

wherein the compensation block contains a first compensation element, and a second compensation element,

the first compensation element is located next to the redirecting optical element along the direction of radiation emitted from at least one projector and is characterized by zero optical power in the vertical direction in relation to the eyes of the observer and negative optical power in the horizontal direction in relation to the eyes of the observer,

the second compensation element is located between the retroreflector and the optical light-scattering element along the direction of radiation emitted from at least one projector and is characterized by zero optical power in the vertical direction in relation to the eyes of the observer and positive optical power in the horizontal direction in relation to the eyes of the observer.

In this case, the retroreflector, made in the form of a set of one-dimensional rectangular prisms elongated in the vertical direction with a reflective coating on the faces of the prisms, may additionally contain an absorbing coating on the ribs at the tops and/or bases of the prisms to ensure reflection of radiation from at least one projector without loss to the scattering of light in the horizontal direction relative to the eyes of the observer, caused by the scattering of light on the edges of the prisms at the tops and/or bases, and the scattering and absorption of radiation within the material of the prisms.

In addition, the first compensation element having zero optical power in the vertical direction and negative optical power in the horizontal direction is an optical element selected from: a holographic lens, a diffractive lens, a Fresnel lens, a geometric phase lens, a metalens, and the second compensation element , having zero optical power in the vertical direction relative to the eyes of the observer and positive optical power in the horizontal direction relative to the eyes of the observer, is an optical element selected from: a holographic lens, a diffractive lens, a Fresnel lens, a geometric phase lens, a metalens.

According to an embodiment of the invention of a device for forming a multi-angle three-dimensional (3D) projection-type image, the redirecting optical element is designed in such a way that it allows each of at least one projector to be spaced apart from the geometric center of at least one corresponding viewing area in a vertical plane relative to the eyes of the observer , and placing each of the at least one projector above and/or below the viewing area.

In addition, the device includes a radiation source configured to direct radiation to the screen unit and integrated into each of the at least one projector.

According to yet another embodiment of the invention, the projection-type multi-view three-dimensional (3D) image generating device further comprises an array of switchable lenses optically coupled to at least one projector to form at least one viewing zone.

In this case, each switchable lens in the line of switchable lenses is a lens configured to transfer an image formed by at least one projector to a screen unit to form at least one viewing area.

The projection-type multi-view three-dimensional (3D) imaging device also includes a tracking device configured to track the position of at least one of the user's head, eyes, pupils, and connectable to at least one projector and switchable lens array, respectively.

The projection-type multi-angle three-dimensional (3D) image generating device also includes a control unit connected to at least one projector, a tracking device, and a line of switchable lenses, and configured to control at least one projector, a tracking device, and a line of switchable lenses.

In addition, in the device in the device for forming a multi-angle three-dimensional (3D) image of the projection type, the retroreflector is designed in such a way that the reflection of radiation from at least one projector occurs on the outer surface of the retroreflector, formed by a set of rectangular prisms, and which is the first surface along the direction of the radiation emitted from at least one projector without loss of light scattering in the horizontal direction relative to the eyes of the observer, and the period (p) of the retroreflector is the distance between the vertices of adjacent prisms and, taking into account the angular resolution of the observer's eye, must satisfy the following expression:

L⋅ tanω>p> , (1)

where ω is the angular resolution of the eye, L is the distance from the screen to the observer, λ is the maximum wavelength from the range of operating wavelengths of the projector, W is the width of the viewing area.

In this case, the operating wavelength range of at least one projector is from 400 nm to 700 nm.

In a device for forming a multi-angle three-dimensional (3D) projection-type image, the optical light-scattering element is a holographic diffuser and/or a diffuser made of frosted glass with the ability to scatter radiation in the vertical direction relative to the observer’s eye or is a diffraction grating of an arbitrary type, where changing the grating period (p ₁ , p ₂ , ... p _N ), ensuring the formation of an expanded viewing area in the vertical direction.

In addition, the light-scattering optical element may be one of: a holographic lens array, a geometric phase lens array, a metalens array capable of scattering light in a vertical direction, or a two-dimensional lens element array consisting of a set of lenses arranged along the X and Y axes, with the ability to provide light dispersion in the vertical direction, and, if necessary, in the horizontal direction.

In a device for forming a multi-angle three-dimensional (3D) image of the projection type, the redirecting optical element has an off-axis parameter (OA), which determines the displacement of the optical axis of the optical redirecting element from the optical axis of the device, which is given by the following relationship:

OA~T/2,

where OA is the off-axis parameter of the redirecting optical element, T is the distance from the radiation source, which is at least one projector, to the observer’s eye.

In this case, the redirecting optical element is an optical element selected from: a holographic lens, a diffractive lens, a Fresnel lens, a geometric phase lens, a metalens.

In a device for forming a multi-angle three-dimensional (3D) projection-type image, at least one of the optical elements of the screen unit: a retroreflector, an optical light-scattering element, an optical redirecting element, the first and second compensation elements, is configured to optionally apply a filter coating to filter out unwanted radiation for the operation of the device; a reflective coating to increase the reflectance of the surfaces of optical elements, an antireflective coating to increase the transmittance of the surfaces of optical elements.

A device for forming a multi-angle three-dimensional (3D) image of a projection type according to one embodiment is configured to form an autostereoscopic image and contains at least two stereoscopic projectors.

A device for generating a multi-angle three-dimensional (3D) image of a projection type according to one embodiment is configured to form a holographic 3D image and contains one holographic projector.

Brief description of drawings

The above and other features and advantages of the present invention will become more apparent from the following description, taken in conjunction with the drawings, in which:

FIG. 1A is a diagram of total internal reflection (TIR) of radiation passing through a retroreflective film using glass beads or spherical lenses as reflective elements in the prior art.

Fig. 1B is a diagram of total internal reflection (TIR) of radiation passing through a retroreflective film, where retroreflective microprisms are used as reflective elements according to the prior art.

Fig. 1C is a schematic representation of the overlay of viewing areas for the left (L) and right eye (R) when using the retroreflective film according to Figs. 1A, 1B according to the prior art.

Fig. 2A shows a diagram of the formation of a 3D image on a screen in a configuration in which the projector is placed at a distance from the viewer's head and stereo glasses are not used according to the prior art.

Fig. 2B shows a diagram of the formation of a 3D image on a large screen in a configuration in which the projector is placed at a distance from the viewer's head and stereo glasses are not used according to the prior art.

FIG. 2C is a schematic side view (Y-Z plane) of the configuration of a 3D image forming device with a radiation source and a set of projectors positioned in close proximity to the viewing areas and the head of an observer 1 when forming a 3D image according to the prior art.

FIG. 2D is a schematic top view (X-Z plane) of the configuration of a 3D image forming device with superimposed viewing areas when the radiation source and a set of projectors are located in close proximity to the viewing areas and the head of observer 1 when forming a 3D image according to the prior art.

Fig. 3A is a schematic representation of a cross-section of a reflective film consisting of an array of one-dimensional triangular prisms with a reflective coating on the side faces of the prism and absorbing coatings on the edges, where the arrows indicate the rays reflected from the side faces of the prism, and the crossed out arrows indicate the rays absorbed by the areas of the prism with the applied absorbent coating.

FIG. 3B is a schematic side view (Y-Z plane) of the configuration of a 3D imaging device according to the invention, with at least one projector and a radiation source arranged (in the context of the present invention, the radiation source and the projector are combined in the projector and are hereinafter referred to as the projector) at a distance from the relevant viewing area and the observer's head.

FIG. 3C is a schematic top view (X-Z plane) of the configuration of a multi-view 3D imaging device according to the invention, with separated viewing areas with at least two projectors positioned at a distance from the respective viewing areas and the viewer's head.

FIG. 4A is a schematic side view (Y-Z plane) of a ray propagation pattern in a multi-view 3D imaging device, where H is the height of the viewing area.

Fig. 4B is a top view (X-Z plane) of the ray propagation pattern in a multi-angle 3D image generating device, where L is the distance from the screen to the observer, W is the width of the viewing area for the right and left eyes, respectively.

Fig. 5A shows a version of a retroreflector without an absorbing coating, made in the form of a one-dimensional set of rectangular prisms elongated vertically.

Figure 5B shows a variant of a 2D retroreflector consisting of a two-dimensional set of prisms with or without an absorbing coating.

Figure 5C shows a variant of a 1D retroreflector consisting of a one-dimensional set of rectangular total internal reflection (TIR) prisms elongated vertically.

FIG. 5D shows a 1D glass bead-based retroreflector that uses glass beads or spherical lenses as reflective elements.

Fig. 6A is a schematic diagram of the arrangement of an optical light-diffusing element with the ability to scatter radiation in the vertical direction relative to the eye of the observer 1, where the optical light-diffusing element (VD), located next to the retroreflector (1D RR), is an array of one-dimensional (1D) lenticular lenses

FIG. 6B is a schematic diagram of an arrangement of an optical light-diffusing element (VD) configured to disperse light in a vertical direction relative to the eye of an observer 1, where the optical light-diffusing element (VD) located next to a retroreflector (1D RR) is an array two-dimensional (2D) lens elements, consisting of a set of lenses distributed along the X and Y axes, and provides radiation dispersion in two directions.

FIG. 6C is a schematic diagram of an arrangement of an optical light-diffusing element (VD) configured to diffuse light in a vertical direction relative to the eye of an observer 1, where the optical light-diffusing element VD located next to a retroreflector (1D RR) is one-dimensional (1D ) diffuser, such as a holographic diffuser, and a diffuser made of frosted glass.

Fig. 6D is a schematic diagram of the arrangement of an optical light-diffusing element (VD), configured to scatter light in a vertical direction relative to the eye of the observer 1, where the optical light-diffusing element VD, located next to the retroreflector (1D RR), is a diffraction grating of an arbitrary type.

FIG. 7A is a schematic side view (Y-Z plane) of a ray propagation pattern in a multi-view 3D imaging device according to the prior art.

FIG. 7B is a schematic side view (Y-Z plane) of a ray propagation pattern in a multi-view 3D imaging device including a retroreflector, an optical light-scattering element, and a redirecting optical element according to an embodiment of the claimed invention.

FIG. 7C is a schematic top view (X-Z plane) of a ray propagation circuit in a multi-view 3D imaging device including a retroreflector, an optical light-scattering element, a redirecting optical element, and two projectors according to an embodiment of the claimed invention.

Fig. 7D is a schematic side view (Y-Z plane) of the ray propagation pattern in a multi-angle 3D image forming device, including a retroreflector and a redirecting optical element according to an embodiment of the claimed invention.

FIG. 8A shows a radiation intensity distribution map for a multi-angle 3D image forming device without a redirecting optical element.

FIG. 8B shows a radiation intensity distribution map for a 3D shaping device with a redirecting optical element according to an embodiment of the invention.

FIG. 9A is a top view (X-Z plane) of a ray propagation pattern in a multi-view 3D imaging device including a screen including a reflector, an optical light-scattering element, and a redirecting optical element according to an embodiment of the invention.

FIG. 9B is a diagram of rays entering the pupil of the eye as they propagate through the multi-view 3D image generating device according to FIG. 9A.

FIG. 9C is a top view (X-Z plane) of a ray propagation pattern in a multi-view 3D imaging device including a screen including a reflector, an optical light-diffusing element, a redirecting optical element, and a compensation unit according to an embodiment of the invention.

FIG. 9D is a diagram of rays entering the pupil of the eye as they propagate through the multi-view 3D image generating device according to FIG. 9C.

FIG. 10A is a top view (X-Z plane) of a ray propagation pattern in a multi-view 3D imaging apparatus that provides widescreen 3D imaging on a large screen according to an embodiment of the invention.

FIG. 10B is a diagram of rays entering the pupil of the eye as they propagate through the multi-view 3D imaging device of FIG. 10A.

Fig. 11A shows a radiation intensity distribution map for a device for forming a multi-angle 3D image without a compensation unit, obtained on the detector.

Fig. 11B is a cross-sectional graph of the radiation intensity distribution map according to Fig. 11A, where the X-axis is the detector coordinate value along the X-axis, and the Y-axis is the intensity value (I).

Fig. 11C shows a radiation intensity distribution map for a 3D image forming device with a compensation unit, obtained at the detector.

Fig. 11D is a cross-sectional graph of the radiation intensity distribution map according to Fig. 11C, where the X-axis is the detector coordinate values along the X-axis, and the Y-axis is the intensity values (I).

FIG. 12A is a schematic representation of a ray propagation circuit in a 3D imaging apparatus with a curved screen according to an embodiment of the invention.

FIG. 12B is a schematic representation of a ray propagation circuit in a multi-view 3D imaging device with a line of switchable lenses according to an embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

INVENTIONS

All documents mentioned in this application form an integral part of the description of the application, i.e. their disclosures are hereby incorporated by reference in their entirety.

References to elements in the singular are to be understood to include elements in the plural and vice versa, unless otherwise expressly stated or clearly evident from the context.

In this application, the statement of limits of values is not intended to be limiting, but is intended to apply individually to any and all values falling within the limits, unless otherwise stated in this application, and each individual value within such limits is included in the specification as if it were individually provided in this application.

The words "about", "approximately" or similar numerical values should be understood by one skilled in the art to indicate the deviation at which satisfactory performance in the intended application is achieved. Likewise, words referring to an approximate value, such as “approximately” or “substantially”, when used in relation to physical characteristics, should be understood by one skilled in the art to express the limits of deviation that will provide satisfactory performance when used accordingly. , purpose or anything like that.

The ranges of values and/or numbers provided in this application are by way of example only and are not intended to limit the scope of the described embodiments. When limits of values are given, they are intended to include each value within the limits as if they were presented individually, unless otherwise specifically stated. The use of any or all examples, or an introductory word before an example (eg, such or the like) provided in this application is intended only to better illuminate the embodiments and is not intended to limit the scope of the embodiments. Nothing in the specification should be construed as indicating that any unstated element is essential to the practice of the embodiments.

Within the framework of the present invention, the following concepts and terms will be used, the interpretation of which is provided below by the authors of the invention:

An autostereoscopic projection system for forming a 3D image is a system that forms an autostereoscopic image that causes the illusion of volume, that is, a feeling of relief and extension in depth due to the features of binocular vision without the use of additional wearable devices. In which a stereo pair of images is projected onto the screen.

A stereo pair is a pair of flat images of the same object (scene), with differences between the images designed to create a volume effect.

A holographic projection system for forming a 3D image is a system that forms a 3D image by reconstructing the wavefront of the displayed object (scene). In which a holographic image is projected onto a screen.

In the present disclosure, the direction of the horizontal axis (X-axis) is parallel to the line segment connecting the centers of the pupils of the observer's eyes; The direction of the vertical axis (Y-axis) is orthogonal to the direction of the horizontal axis.

As used herein, reference to a direction in the vertical or horizontal direction means a direction along the vertical or horizontal axis, respectively.

A horizontal plane , as used herein, means the plane in which the horizontal axis lies.

The vertical plane , as used herein, means the plane in which the vertical axis lies.

A diffractive optical element (DOE) is a diffractive microstructure that performs amplitude-phase modulation of transmitted or reflected radiation.

Holographic optical element (HOE) is a diffractive optical element manufactured by light wave interference methods.

It should be noted that both the diffractive optical element (DOE) and the holographic optical element (HOE) are based on essentially the same physical principle, that is, both types of these optical elements can essentially be classified as diffractive optical elements. The difference between them is that diffractive optical elements are called optical elements in which diffraction occurs on the surface relief, and holographic optical elements are called gratings in which diffraction occurs in the material due to a local change in its optical properties.

Field of view is the angle between two rays passing through the center of the entrance pupil of the lens (lens) to the most distant displayed points of the object from the optical axis in object space.

Viewing zone (window) is an area of space in which the pupil of the eye can observe the corresponding image of a stereo pair or holographic image.

Useful viewing area - in the context of the present invention, this is the area selected from the viewing area in which the user's head is most likely to be located when using the device.

Dead viewing zone - within the framework of the present invention, this is the area selected from the viewing zone in which the user's head is least likely to be located when using the device.

Field of view angle is the angle between the optical axis and the ray passing through the point of the object in the field of view.

Recording material is a substance used to record holograms (the full wavefront of an object/image/scene).

Within the framework of this description, the terms “recording material”, “holographic material” are used as equivalent synonyms.

Imaging device efficiency , in the context of the present invention, is the ratio of the amount of radiation emitted by the projector to the amount of radiation entering the useful viewing area.

Next, the main design solutions of the claimed invention will be described, which can be divided into:

Key Position 1, Key Position 2 and Key Position 3.

Key point 1 - providing a highly efficient one-dimensional (1D) retroreflector with low scattering in the range from 0 to 1 degree, while horizontally the rays are reflected in the same direction in which they fall on the reflector, and vertically the rays are reflected as from a regular mirror. In this case, the scattering of the reflector in the horizontal direction is no more than one degree. According to Key Provision 1, the claimed invention also provides an optical light-scattering element (diffuser), configured to scatter radiation along a vertical axis, which together with a retroreflector constitute a screen unit (hereinafter referred to as a screen). In this case, the optical light-scattering element is configured to form a viewing area in the vertical plane in order to prevent the eyes from fixing in a certain location (vertically).

Key Point 2: Providing an optical element that has a spatially distributed scattering function and transfers radiation from the entire viewing area to the useful viewing area, significantly increasing the efficiency of the device.

Key point 3: the use of an optical element with negative field curvature, which performs the function of a compensation element and provides compensation for distortion of viewing areas to form a wide picture (image).

The above key provisions provide the following effects of the claimed invention:

- Formation of a 3D image without the use of auxiliary viewing tools (stereo glasses),

- providing narrow, for example 1 degree, and separated viewing areas for each eye of the observer,

- ensuring high quality 3D images,

- ensuring a large size of the generated 3D image. The diagonal angular size of the generated image can be, for example, 40, 60, 120, etc. degrees.

Next, we will dwell in more detail on Key Provision 1, i.e. Consider the formation of a reflector with low dispersion in the horizontal direction and an optical light-scattering element.

As previously described with reference to FIGS. 1A, 1B, and 1C, various types of reflective reflectors are available in the art, such as glass bead reflective films (see FIG. 1A), which use glass beads or spherical lenses as reflective elements and reflective films in which retroreflective microprisms are used as reflective elements (see Fig. 1B). The light in such reflective (retroreflective) films undergoes many reflections and refractions at the interfaces, which causes very high radiation dispersion at the exit from the film. In addition, radiation scattering is often caused by defects in the material from which the reflector is made, for example, the presence of bubbles or the presence of microparticles. In addition, scattering is often caused by manufacturer errors, for example, when manufacturing reflectors in the form of a microprism array, the angle at the tops and bases of the prisms (see Fig. 1B) should ideally be 90 degrees, which is very difficult to achieve with available optical surface processing technologies , so the peaks and valleys have some slight rounding, which causes radiation to scatter and widen the viewing area. All of the above problems with prior art retroreflectors cause the following problems in known 3D image forming devices:

- overlap of viewing areas,

- low quality of the generated 3D image (occurrence of crosstalk, ghosting,

- high dispersion, which is more than 2 degrees in the horizontal direction of the screen,

- low contrast and low efficiency of the generated 3D image,

- viewing areas are located in close proximity to the projector (there is no vertical separation (along the Y axis).

FIG. 2C is a schematic side view (Y-Z plane) of the configuration of a 3D image forming device with the location of viewing zones (VZ), radiation source and at least one projector (2) in close proximity to the head of the observer 1, and a 1D light reflector (1D RR ) according to the prior art. In this configuration, the projectors and the radiation source (in the present invention, the radiation source and the projector are combined in the projector and are hereinafter referred to as the projector) are located near the observer's head.

FIG. 2D is a schematic top view (X-Z plane) of the configuration of a 3D imaging device with the location of viewing zones (VZ), a radiation source and at least one projector (2) in close proximity to the observer's head (1), the device also includes a 1D light reflector (1D RR) as a screen, as well as an optical light diffusion element (VD) according to the prior art.

Figure 2D shows an overlap of viewing zones (VZ) when projectors (2) are positioned next to the viewer's head (1), resulting in a 3D image that is low resolution and of poor quality.

The claimed invention is aimed at eliminating the above problems; for this purpose, the authors of the invention proposed the design of a light reflector formed from an opaque one-dimensional matrix of 90-degree prisms with mirror side faces, using reflection from the outer surface of the side face of at least one prism from the prism matrix, excluding the beam from entering inside prism material. In this case, the ribs (prisms) at the top and base of each prism from the prism matrix are covered with an absorbing coating, which prevents radiation from scattering on them. This ensures the smallest width of one viewing area and a clear vertical boundary of the viewing area, which ensures a smooth transition between 3D image angles without noticeable breaks and transitions and at the same time eliminates their overlapping.

This embodiment of the reflector in the projection-type 3D image forming device according to the invention makes a significant contribution to the following effects provided by the claimed 3D image forming device:

- providing multi-angle 3D images without the use of wearable aids, for example, stereo glasses,

- no overlap or overlap of viewing areas,

- high signal-to-noise ratio (SNR) (for example, 10,15,20 and above), low phantom image/interference,

- high quality of the generated 3D image (high contrast and resolution of the generated 3D image),

- separated viewing areas with a wide field of view (FoV) in the vertical direction.

In this case, Fig. 3A schematically shows a cross-section of a reflective film consisting of an array of one-dimensional triangular prisms, where arrows indicate rays reflected from the side faces of the prism, and crossed out arrows indicate rays absorbed by areas of the prism coated with an absorbent coating.

In fig. 3B is a schematic side view (Y-Z plane) of the configuration of a multi-angle 3D image forming device according to the claimed invention with the arrangement of viewing zones (VZ), a radiation source and at least one projector 2 (in this embodiment, two projectors are presented) at a distance from the viewing zone VZ and head of observer 1. The device also contains a screen consisting of a one-dimensional light reflector (1D RR) and an optical light-scattering element configured to scatter rays along the vertical axis.

Figure 3C schematically shows a top view (X-Z plane) of the configuration of a device for forming a multi-angle 3D image according to the claimed invention with the location of viewing zones (VZ), a radiation source and at least one projector (2) (in this embodiment, two projectors are presented) at a distance from the viewing area and the head of observer 1. The device also contains a screen consisting of a one-dimensional light reflector (1D RR) and an optical light-scattering element (VD), configured to scatter rays along the vertical axis.

Figure 3C demonstrates the separation of viewing zones (VZ) when two projectors 2 are positioned at a distance from the viewing zones VZ and the head of the observer 1, resulting in a 3D image that is characterized by high resolution and high quality, as seen in Fig. 3C.

Next, we will consider in more detail the operation of the retroreflector according to the claimed invention with reference to Fig. 3A,4A,4B.

FIG. 4A is a side view (Y-Z plane) of a ray propagation pattern in a multi-view 3D imaging device, where H is the height of the viewing area.

Figure 4B is a top view (X-Z plane) of the ray propagation pattern in a multi-view 3D imaging device, where L is the distance from the screen to the observer, W is the viewing area width for the right and left eyes, respectively. In the X-Z plane, as shown in Fig. 4B, the position of the head(s) of observer 1 coincides with the position of the projectors 2. The distances from the screen to the observer and from the projector(s) to the observer are equal.

In the context of the present invention, one or more projectors are considered as a light source. In this case, for the formation of a holographic 3D image, at least one projector 2 is provided, and for an autostereoscopic image, at least two projectors 2 are provided, each of which forms an image for one viewing area for the corresponding eye, right or left. The projectors 2 are placed in the same vertical plane, but in different horizontal planes from the plane in which the viewing zone is located, in particular above or below the specified viewing zone (VZ), see. Fig.4a. The image formed by each of at least two projectors 2 falls at an angle onto a screen consisting of a retroreflector 3 and an optical light-scattering element 4, configured to scatter radiation along a vertical axis, which together form the screen.

Retroreflector 3 is an opaque film consisting of a one-dimensional (with horizontal periodicity) set (array) of rectangular prisms, elongated vertically, with a reflective coating on the edges of the prisms and an absorbing coating on the ribs at the tops and bases of the prisms. Reflection occurs on the outer surface of the retroreflector, formed by a set of rectangular prisms, and being the first surface along the path of rays from the projector 2 to the screen of the retroreflector 3 and the optical light-scattering element 4, without losses due to light scattering on the edges of the prisms at the tops and bases, without scattering and absorption radiation inside the material. Thus, retroreflection occurs in the horizontal direction with high efficiency and low scattering into the viewing zones (VZ). In addition, taking into account diffraction and angular resolution of the eye, the step or (period) (p) of the retroreflector, see Fig. 3a, must correspond to the following expression:

L⋅ tanω>p> , (1)

where ω is the angular resolution of the eye, L is the distance from the screen to the observer, λ is the maximum wavelength from the range of operating wavelengths of the projector, W is the width of the viewing area. It should be noted that the wavelength range at which the projector operates is the visible range of electromagnetic radiation (400 nm -700 nm).

It should be noted that the number of rectangular prisms in a set or array of prisms is determined by the size of the screen, which is selected based on the area of use: home or public cinema, divided by the period (p) of the retroreflector.

It should be noted that the beam directed from the projector 2 falls on the one-dimensional reflector 3 at a certain angle, and is reflected horizontally in the same direction in which it falls on the reflector, and vertically the beam is reflected as from an ordinary mirror. In this case, a viewing area is not formed vertically, and with a fixed position of the observer’s eye, only a small part of the image will be visible. To form a vertical viewing area in which the observer's eye will see the full image (when located inside the viewing area), the authors of the invention included an optical light-scattering element 4 in the screen design, which scatters each ray from each point of the screen in the vertical direction, thus forming a viewing area . The effect of making the screen of the 3D image forming device according to the invention is as follows:

low scattering along the horizontal axis of the screen is ensured; elongated viewing area along the vertical axis; The viewing areas for the observer's left and right eyes do not overlap. Thin (unscattered) and large vertical viewing area, high signal-to-noise ratio, low crosstalk.

Next, we will consider embodiments of retroreflectors that can be used in a 3D image forming device according to the invention.

According to the preferred embodiment, the retroreflector 3 is made with a reflective coating on the edges of the prisms, but without the absorbing coating of Fig. 5A and is a one-dimensional set (array) of rectangular prisms elongated vertically. In this case, the beam directed from the projector falls on the reflector according to the invention at a certain angle, and horizontally, essentially without loss, is reflected in the same direction in which it falls on the reflector, and vertically the beam is reflected as from an ordinary mirror . Thus, the beam directed from the projector is almost completely reflected from the outer surface of the prism without going inside the material, which provides a significant reduction in the degree of dispersion in the horizontal direction of the retroreflector according to the claimed invention, compared to solutions known from the prior art.

However, the production of such optical elements requires high manufacturing precision, which is not always possible to achieve in real production. To eliminate even minimal defects at the tops and bases of the prisms that arise as a result of manufacturing errors, the authors of the invention additionally provide for the presence of an absorbing coating on the ribs at the tops and/or bases of the prisms; in this case, scattering from the tops and bases will be practically completely eliminated.

As a retroreflector, according to another embodiment according to Fig. 5B, a 2D retroreflector consisting of a two-dimensional set of prisms with or without an absorbent coating can be used. The 2D retroreflector is widely known in the relevant field of technology: https://ru.wikipedia.org/wiki/%D0%A3%D0%B3%D0%BE%D0%BB%D0%BA%D0%BE%D0%B2% D1%8B%D0%B9_%D0%BE%D1%82%D1%80%D0%B0%D0%B6%D0%B0%D1%82%D0%B5%D0%BB%D1%8C

This type of reflector is characterized by retro-reflection along two axes (unlike 1D reflector) and using this type of reflector in a display will result in a fixed and small viewing area with high brightness. Due to retroreflection along two axes, the position of the center of the formed viewing area will coincide with the center projector lens, and, with embodiments of a 2D retroreflector known from the prior art, it is impossible to separate the center of the formed viewing area from the center of the projector lens. Also, to increase/expand the viewing area of a display with a 2D retroreflector, a different type of diffuser is required compared to the claimed invention.

According to another embodiment with reference to Fig. 5C, the retroreflector is a one-dimensional array of rectangular total internal reflection (TIR) prisms elongated vertically. In this case, the beam from the projector penetrates at a certain angle into the inside of the prism and undergoes refraction and reflection there. In this case, horizontally the rays are reflected in the same direction in which they fall on the reflector, and vertically the rays are reflected as from an ordinary mirror and then exit the prism. This type of reflector is characterized by quite significant scattering and dispersion resulting from the propagation of light through the prism material, in addition to scattering from defects in the prism's manufacturing. At the same time, the production of such a TIR retroreflector is high-tech.

As a retroreflector, according to another embodiment (FIG. 5D), a glass bead reflector may be used, which uses glass beads or spherical lenses as reflective elements. The beam from the projector penetrates at a certain angle into the inside of the ball, undergoes reflection and refraction there, and leaves the ball at the same angle (2D retroreflection, along two axes like a 2D retroreflector, consisting of a two-dimensional set of prisms), while the surface of the ball is partially covered with reflective material. /mirror coating from which the beam is reflected. This type of reflector is easy to manufacture and provides a fixed, small viewing area with high brightness. However, with this design of the retroreflector, a large scattering of the rays occurs, which causes an overlap of viewing areas for the left and right eyes of the observer. Due to retroreflection along two axes, the position of the center of the formed viewing area will coincide with the center of the projector lens and, with embodiments of a reflector based on glass beads, known from the prior art: https://ru.wikipedia.org/wiki/%D0%9A%D0 %B0%D1%82%D0%B0%D1%84%D0%BE%D1%82,

It is impossible to separate the center of the formed viewing area from the center of the projector lens. Also, to increase/expand the viewing area of a display with a reflector based on glass beads, a different type of diffuser is required compared to the claimed invention.

Thus, the embodiments of the retroreflectors described with reference to Figs. 5B-5D have a number of disadvantages that significantly deteriorate the quality of the generated 3D image, while the design of the screen with a one-dimensional retroreflector with a reflective coating on the outer edges of the prisms and an absorbing coating on the edges at the vertices and the bases of the prisms, according to the claimed invention, eliminates all of the above disadvantages of known retroreflectors.

Next, with reference to figures 6A-6D, possible embodiments of the optical light-scattering elements used in the claimed invention will be shown.

Various types of optical elements used as light diffusers are known from the prior art, with diffusers typically providing the formation of light beams with a specific scattering pattern. The objective of the claimed invention is to provide, using an optical light-scattering element, the scattering of rays reflected from a retroreflector in the vertical direction, thus ensuring the creation of the necessary scattering pattern in accordance with the position of the observer's eye and the required size of the viewing area.

Fig. 6A is a schematic diagram of the arrangement of an optical light-diffusing element in relation to the eye of an observer 1, where the optical light-diffusing element (VD), configured to disperse rays in the vertical direction, and located next to the retroreflector (1D RR), is an array of one-dimensional ( 1D) lenticular lenses. In this case, an array of holographic lenses, an array of diffractive lenses, an array of lenses, an array of lenses with a geometric phase, and an array of metalens can be used as optical light-scattering elements.

The use of one-dimensional (1D) optical elements as an optical light-scattering element in a 3D image forming device provides increased flexibility in system design due to the variability (the ability to use a variety of optical elements) in the choice of optical elements and ensures the formation of an expanded viewing area in the vertical plane. FIG. 6B is a schematic diagram of an arrangement of an optical light-diffusing element (VD) configured to diffuse light in a vertical direction relative to the eye of the observer 1, where the optical light-diffusing element (diffuser (VD)) located adjacent to the retroreflector (1D RR) is an array of two-dimensional (2D) lens elements consisting of a set of lenses distributed along the X and Y axes, providing radiation scattering in two directions. In this case, an array of holographic lenses, an array of diffractive lenses, an array of lenses, an array of lenses with a geometric phase, and an array of metalens can be used as optical light-scattering elements.

The use of two-dimensional (2D) optical elements as an optical light-scattering element in a 3D imaging device provides increased flexibility in system design and provides an expanded field of view in the horizontal (if necessary) and vertical planes.

FIG. 6C is a schematic diagram of an arrangement of an optical light-diffusing element in relation to the eye of an observer 1, wherein the optical light-diffusing element (VD) located next to a retroreflector (1D RR) is a one-dimensional (1D) diffuser. In this case, a holographic diffuser and a diffuser made of frosted glass can be used as optical light-scattering elements. Features of the above diffusers are widely known from the prior art and are disclosed in detail in the following publication: https://www.rp-photonics.com/diffusers.html

The use of an optical light-scattering element, i.e. a one-dimensional (1D) diffuser provides the formation of an expanded viewing area in the vertical direction.

Figure 6D schematically shows the arrangement of the optical light-scattering element in relation to the eye of the observer 1, where the optical light-scattering element (VD), located next to the retroreflector (1D RR), is a diffraction grating of an arbitrary type, where the change in the period of the grating (p ₁ , p ₂ , …, p _N ) allows you to create a viewing area of the required size.

The use of a diffraction grating as an optical light scattering element provides an expanded viewing area in the vertical direction and provides increased flexibility in system design.

Features of various diffuser designs in various optical systems, as well as methods for their selection depending on the required parameters, are disclosed in the following publication : https://www.edmundoptics.com/knowledge-center/application-notes/optics/diffuser-selection- guide/

Next, we will dwell in more detail on Key Position 2, which is based on providing an optical element that is characterized by a spatially distributed scattering function, and ensures the transfer of radiation from the entire viewing area to the useful viewing area, significantly increasing the efficiency of the device.

Features of the implementation of Key Provision 2 will be further described with reference to figures 7A, 7B, 7C, 7D.

FIG. 7A is a schematic side view (Y-Z plane) of the ray propagation pattern of a prior art 3D imaging apparatus. The device contains: a retroreflector 3, an optical light-scattering element 4, designed to disperse rays in the vertical direction, as well as at least one projector 2, which is fixed at a distance from the user's head 1. No additional wearable devices are used, for example, glasses. As can be seen in diagram 7A, the rays of light emitted from the projector 2 fall on the retroreflector 3 and are reflected vertically from the retroreflector as from an ordinary mirror, then all the rays reflected from the retroreflector 3 fall on the optical light-scattering element 4, which ensures the scattering of the rays in the vertical direction , which forms a long (highly scattered) viewing area, which leads to only a small part of the rays entering the pupil of observer 1. In this case, in the horizontal direction, these rays are reflected from the reflector 3 in the same direction in which they fall on it and, when passing through optical light-scattering element 4, do not change their direction (do not scatter in the horizontal plane).

Since FIG. 7A is a view in the Y-Z plane, rays reflected from the reflector in the horizontal direction are not visible in the vertical plane. At the same time, because The radiation through the optical light-scattering element is vertically scattered over a large (long) viewing area, its density (correlates with the brightness of the image) in the useful viewing area is low. And dead zones are formed - an area in which the pupil of the eye can observe the corresponding image of a stereo pair or a holographic image, but the probability of the pupil of the observer’s eye falling into such an area is close to zero. Thus, as clearly seen in Fig. 7A, the image formed with such a scheme has low brightness and low projection efficiency due to light loss in the dead zone.

Fig. 7B is a schematic side view (Y-Z plane) of the ray propagation pattern in a multi-angle 3D image forming device according to the claimed invention, which includes a retroreflector 3, an optical light-scattering element 4 configured to disperse radiation in the vertical direction, and at least one projector 2 located at a distance from the head of the user 1, and a redirecting optical element 5, essentially performing the function of a radiation condenser with an offset optical axis relative to the optical axis of the device for forming a multi-angle 3D image. The redirecting optical element 5 is designed in such a way that it is characterized by zero optical power in the horizontal direction and a given optical power in the vertical direction. For example, in the case of a personal gaming monitor, when the distance from the user's head to the screen is small, for example, 0.5 m, the optical power is equal to 2 diopters. In the case of a home theater, when the distance from the user's head to the screen is more significant, for example, 2 meters, the optical power of the redirecting element 5 is equal to 0.5 diopters. Similarly, for a public cinema where the distance is large, for example 10 meters, the optical power is 0.1 diopter. The inclusion in the optical circuit of the device of a redirecting optical element with zero optical power in the horizontal direction and a given optical power in the vertical direction ensures the redirection of rays entering the dead viewing area when reflected from the retroreflector 3 and passing through the optical light-scattering element 4 into the useful viewing area. It should be noted that within the framework of this description, an indication of the horizontal direction implies a direction along the horizontal axis (X-axis), which is parallel to the segment connecting the centers of the pupils of the observer's eyes; and indicating a vertical direction implies a vertical axis direction (Y axis) that is orthogonal to the horizontal axis direction. In this case, L is the distance from the screen, consisting of a retroreflector 3 and an optical light-scattering element 4, to the observer, and T is the distance from the radiation source, which is at least one projector 2, to the eye of the observer 1.

Thus, as is clearly seen in Fig. 7B, with such a screen layout, greater flexibility is achieved in configuring the device for forming a multi-angle 3D image with different locations of projectors, the device is compact and has high efficiency in the useful viewing area, which allows you to form a clear and bright 3D image without using viewing aids, such as stereo glasses, while ensuring a high signal-to-noise ratio.

Fig. 7C schematically shows a top view (X-Z plane) of the ray propagation diagram in a device for forming a multi-angle 3D image, according to the claimed invention, which presents a retroreflector 3, an optical light-scattering element 4, configured to scatter radiation in the vertical direction, as well as at least at least one projector 2 (in this diagram there are 2 projectors), located at a distance from the user’s head 1 (not visible in the X-Z plane), and a redirecting optical element 5, essentially performing the function of a radiation condenser with an offset optical axis relative to the optical axis of the formation device multi-angle 3D image, where L is the distance from the screen to the observer, which in the top view coincides with the projectors 2.

Figure 7D schematically shows a side view (Y-Z plane) of the ray propagation circuit in a device for forming a multi-angle 3D image according to the claimed invention, in which, for clarity of the function of the redirecting optical element 5, the optical light-scattering element 4 is omitted from the circuit, where L is the distance from the screen, consisting of a retroreflector 3 and an optical light-scattering element 4 (not shown), to the observer 1, T is the distance from the radiation source, which is at least one projector 2 to the eye of the observer 1. It should be noted that in the device for forming a multi-angle 3D image according to invention with reference to Fig. 7D:

1) one or more projectors 2 also act as a radiation source and, according to the claimed invention, are placed in the same vertical plane in which the useful viewing area (VZ) is located, but in different horizontal planes, in particular above or below the specified useful viewing area (VZ) at a distance T. Each of the at least one projector 2 produces an image for one viewing area for the corresponding eye, right or left;

2) radiation emitted by each of at least one projector 2 falls at an angle onto a screen consisting of a retroreflector 3 and an optical light-scattering element 4, configured to scatter radiation along the vertical axis, as well as a redirecting optical element 5, which together form the screen ;

3) retroreflector 3 is an opaque film consisting of a one-dimensional (with horizontal periodicity) set (array) of rectangular prisms, elongated vertically with a reflective coating on the edges of the prisms and an absorbing coating on the edges at the tops and bases of the prisms. Reflection occurs on the outer surface of the retroreflector 3, formed by a set of rectangular prisms, which is the first surface along the path of rays from the projector 2 to the screen without losses due to light scattering on the edges of the prisms at the tops and bases, without scattering and absorption of radiation inside the material. Thus, retroreflection occurs in the horizontal direction with high efficiency and low scattering into the viewing zones (VZ). In addition, taking into account diffraction and angular resolution of the eye, the step or (period) (p) of the retroreflector, see Fig. 3a must correspond to the following expression:

L⋅tgω>p> , (1)

where ω is the angular resolution of the eye, L is the distance from the screen to the observer, λ is the maximum wavelength from the range of operating wavelengths of the projector, W is the width of the viewing area. It should be noted that the beam directed from the projector 2 falls on the one-dimensional retroreflector 3 at a certain angle and is reflected at such an angle. To form a vertical viewing area in which the observer's eye will see the full image (while inside the viewing area), the authors of the invention included an optical light-scattering element 4 in the screen design, which scatters each ray from each point of the screen, thus forming a viewing area;

4) the redirecting optical element 5 performs the function of a radiation condenser and is an optical element with an offset optical axis relative to the optical axis of the 3D image forming device. The redirecting optical element 5 is designed in such a way that it is characterized by zero optical power in the horizontal direction and a given optical power (OP) in the vertical direction, which is inversely proportional to the distance to the viewing zone (VZ), i.e. OP~ (2),

where OP is the optical power, L is the distance from the screen to the observer 1 (m). The off-axis parameter (OA) of the redirecting element 5 must be half the distance from the radiation source, i.e. projector (2) to the geometric center of the useful viewing zone (VZ). It should be noted that the size of the useful viewing area and its geometric center relative to the optical axis of the multi-angle 3D imaging device depend (determine) on the area (area) of use of the 3D imaging device, for example, a home/public cinema.

In addition, the off-axis parameter of the redirecting element 5 is set as follows:

OA~T/2 (3),

where OA is the off-axis parameter of the redirecting element 5, T is the distance from the radiation source, which is at least one projector 2, to the eye of the observer 1.

It should be noted that OA (off-axis parameter of the redirecting element) is the distance between the optical axis of the redirecting element 5 (see AXIS in FIG. 7D) and the optical axis of the multi-view 3D image forming device. The ratio was obtained by the authors of the invention from considerations of geometric optics.

Thus, the inclusion of a redirecting optical element 5 in the circuit of the device for forming a multi-angle 3D image makes it possible to concentrate the light reflected from the retroreflector in the useful viewing area, which increases the brightness of the formed image for the observer.

Figures 8A, 8B show radiation intensity distribution maps for a device for forming a multi-angle 3D image with a redirecting optical element (Figure 8B) and without a guide element (Figure 8A), obtained on a detector in the form of a square, 300×300 mm in size ( -150:+150), located at a distance of 500 mm from the screen (consisting of a retroreflector 3, a diffuser 4, a redirecting optical element 5), while the angle between the optical axis of the projector and the optical axis of the screen is 40 degrees. In this case, the values along the X, Y axes in Figs. 8A, 8B represent the coordinates of the detector, and the radiation intensity scales (I) next to the detector show the intensity of any point and its position on the detector, i.e. intensity distribution.

At the same time, the efficiency of the device, i.e. the amount of light falling from the projector into the formed viewing area in the presence of a redirecting element is 51.3%, and without the specified element only 22.8%, which proves the advantage of the declared device circuit for forming a 3D image.

Next, options for implementing redirecting optical elements will be presented.

Optical elements that collect rays reflected from the reflector 3 and direct them to the useful viewing zone (VZ) can be used as redirecting optical elements.

In one of the implementation options 1), the redirecting elements can be: holographic lenses, diffraction lenses, Fresnel lenses, geometric phase lenses, metalenses, diffraction gratings.

The inclusion of redirecting optical elements of the above option 1) in the device for forming a multi-view 3D image allows increasing flexibility in the design of a device for forming a multi-view 3D image due to the variability (the possibility of using a variety of optical elements) in the choice of optical elements. In one embodiment 2), the redirection optical elements may be active redirection elements or deflectors. Examples of active redirecting elements are disclosed in the publication: https://en.wikipedia.org/wiki/Acousto-optic_modulator

The inclusion of active redirecting elements of the above option 2) in the device for forming a multi-angle 3D image allows you to actively control the redirection of light into the viewing area, but at the same time, the production of such optical elements is complicated by the large size of these elements, which requires more developed production technologies to achieve high accuracy during manufacture.

In yet another embodiment 3), the redirecting optical elements may be a combination of optical elements with different properties. The inventors are considering the possibility of combining different functions of optical elements in a single optical element, for example, combining a diffuser configured to diffuse in the vertical direction and a redirecting optical element into a redirecting element with the additional function of dispersing in the vertical direction.

The inclusion of redirecting optical elements with combined functions in the device for forming a multi-angle 3D image, for example, with a diffuser function according to option 3), reduces the number of elements making up the device and significantly reduces the thickness of the device, but at the same time, optical elements with combined functions are more complex in nature itself, which requires more developed production technologies.

In another embodiment 4), the role of the redirecting element is played by a screen (screen block), which is characterized by curvature in the vertical direction (not shown), and can fully or partially perform the function of redirecting radiation when reflected from the retroreflector 3 and passing through the optical light-scattering element 4, into the viewing zone area VZ, in which the observer's head is located when using the device. This function of redirecting radiation is at least partially performed due to the curvature of the components that make up the screen unit: a retroreflector, an optical light-scattering element configured to scatter light reflected from the retroreflector in the vertical direction relative to the observer's eye, in a vertical plane. In this case, when the redirection function is partially performed due to the curvature of the constituent optical components of the screen, the redirection element is still present in the structure, but is characterized by a different (smaller in magnitude) optical power in the corresponding plane, i.e. the plane in which the redirecting optical element redirects radiation according to the preferred embodiment of the invention, and another off-axis parameter, compared with the specified parameters of the redirecting element in the embodiment with a flat screen unit according to the preferred embodiment of the invention, see Fig. 7B.

The inclusion of redirecting optical elements of complex shape in the device for forming a multi-angle 3D image according to option 4) is characterized by a new ergonomic design, which allows you to turn your head less when viewing the generated image and the effect of complete immersion (immersion effect), which is usually used in planetariums (images are viewed on a round roof), and, at the same time, is complicated by the presence of difficult-to-manufacture optical elements in the device, which requires more developed production technologies.

It should be noted that solutions with a curved/curved display screen are known in the prior art to improve display ergonomics and user immersion, see, for example, the publication: https://insights.samsung.com/2022/11/16/how-a- curved-monitor-brings-ergonomic-benefits-and-productivity-2/ In yet another embodiment 5), the redirecting optical elements have additional optical coatings for various purposes, for example: antireflective coatings to increase the transmittance of the surfaces of the optical elements that transmit radiation , reflective coatings to increase the reflectance of surfaces that reflect radiation and filter coatings to filter unwanted radiation for device operation, as well as beam splitting coatings. The specified coatings are used depending on the required tasks.

The inclusion of redirecting elements with coatings in the device for forming a multi-angle 3D image according to option 5) allows for increased flexibility in designing a device for forming a 3D image, due to the fact that a number of optical coatings have special properties and allow for very diverse work with light. Thanks to this property of optical coatings, specialists in the art can select the required specified parameters of the designed multi-view 3D imaging device from a wide range of options, i.e. At the same time, there is greater flexibility in choosing the required parameters. At the same time, the described redirecting elements with coatings are of great complexity in themselves, which requires more developed production technologies to eliminate the occurrence of parasitic optical effects from additional optical elements.

The key provision 3 of the claimed invention is to provide an optical element with negative field curvature, which serves as a compensation element that compensates for the distortion of viewing areas to form a wide picture (image).

Figure 9A shows a top view (X-Z plane) of the ray propagation diagram in a device for forming a multi-angle 3D image, according to the claimed invention, which uses a screen that consists of a reflector 3, an optical light-scattering element 4 configured to scatter rays in the vertical direction, and redirecting optical element 5, while the device considers two projectors 2 (see Fig. 9A), while the pupils of the user’s eye are located in the same vertical plane, but in different horizontal planes with the projectors 2, L is the distance from the radiation source, in this In this case, its role is played by projectors, up to a screen consisting of a retroreflector 3 and an optical light-scattering element 4 and a redirecting optical element 5. In this case, if it is necessary to form a wide-format 3D image on a large screen, for example, in cinemas, museums, educational institutions, zone distortion is observed viewing, as a result of which not all of the projected image enters the pupil of the eye and part of the formed 3D image along its edges in the horizontal direction is lost. Due to the described aberration, the viewing area becomes blurred/curved in the horizontal direction, and part of the field of view does not fall into the observer's pupil, crosstalk of the viewing areas may occur, and thus the user will see only part of the 3D image which may contain additional spurious Images.

Fig. 9B conventionally shows a diagram of rays entering the pupil of the eye, where it is clearly seen that the central ray, indicated by dots in Fig. 9A and incident on the center of the screen and reflected from it in the same direction, hits the observer’s pupil, see Fig. 9B, where the central, dotted, straight line passes through the pupil of the eye, and the rays propagating along the edges (the rays indicated by solid and dotted lines), see Fig. 9A, do not enter the pupil of the eye, see curved lines (solid and dotted) in Fig. 9B and the edges of the image in the horizontal direction do not fall into the pupil of the eye, which is further illustrated by the figure of a man, the image of which is cut off at the edges.

The inventors have tried to eliminate these disadvantages of the embodiment according to FIG. 9A and FIG. 9B and included in the device circuit a compensation unit with negative field curvature, which compensates for the distortion of viewing areas to form a wide picture (image), see Fig. 9C, which shows a top view (X-Z plane) of the ray propagation scheme in the device for forming a multi-angle 3D image , according to the claimed invention, where a screen is used, which consists of a reflector 3, an optical light-scattering element 4, configured to scatter rays in the vertical direction, a redirecting optical element 5, and a compensation block consisting of the first (7) and second (6) compensation optical elements, while two projectors 2 are considered in the device (see Fig. 9C). It should be noted that the pupils of the user's eye are located in the same vertical plane, but in different horizontal planes with the projectors 2, L is the distance from the radiation source, in this case its role is played by projectors, to the screen consisting of a retroreflector 3, an optical light-scattering element 4 , redirecting optical element 5 and compensation block (compensation elements 6,7). Moreover, if it is necessary to form a wide-format 3D image on a large screen, for example, in cinemas, museums, educational institutions, due to the inclusion of compensation elements in the device, the entire projected image enters the pupil of the eye, and thus, in Fig. 9D, where it is conventionally shown diagram of the rays entering the pupil of the eye, it is clearly seen that the central and side rays, indicated by dots, solid or dotted lines in Fig. 9C, enter the pupil of the observer’s eye, see Fig. 9D, which is further illustrated by the figure of a person, the image of which is presented clearly and is completely observable.

The inclusion of optical compensation elements in the device brings the following effects: no image loss, no crosstalk, no need to use viewing aids such as stereo glasses, obtaining a clear and bright 3D image.

With reference to Fig. 10A, the operation of a multi-angle 3D image forming device will be described, which provides a wide-format 3D image on a large screen, for example, in cinemas, museums, educational institutions if it has a compensation unit.

1) one or more projectors 2 according to the claimed invention are placed in the same vertical plane in which the useful viewing zone (VZ) is located, but in a different horizontal plane, in particular above or below the specified useful viewing zone (VZ). Each of the at least one projector 2 produces an image for one viewing area for the corresponding eye, right or left.

2) the radiation emitted by each of at least one projector 2 falls at an angle onto a screen consisting of a retroreflector 3 and an optical light-scattering element 4, configured to direct the radiation along the vertical axis, a redirecting optical element 5, a compensation block (6, 7) which together form a screen.

3) retroreflector 3 is an opaque film consisting of a one-dimensional (with horizontal periodicity) set (array) of rectangular prisms, elongated vertically with a reflective coating on the edges of the prisms and an absorbing coating on the edges at the tops and bases of the prisms. Reflection occurs on the outer surface of the retroreflector 3, formed by a set of rectangular prisms, which is the first surface along the path of rays from the projector 2 to the screen without losses due to light scattering on the edges of the prisms at the tops and bases, without scattering and absorption of radiation inside the material. Thus, in the horizontal direction, retroreflection occurs with high efficiency and low scattering into the viewing zones (VZ). In addition, taking into account the diffraction and angular resolution of the eye, the step or (period)(p) of the retroreflector, see Fig. 3a, must correspond to the following expression:

L⋅ tanω>p> , (1)

where ω is the angular resolution of the eye, L is the distance from the screen to the observer, λ is the maximum wavelength from the range of operating wavelengths of the projector, W is the width of the viewing area). It should be noted that the beam directed from the projector 2 falls on the one-dimensional retroreflector 3 at a certain angle and is reflected at such an angle. To form a vertical viewing area in which the observer's eye will see the full image (while inside the viewing area), the authors of the invention included an optical light-scattering element 4 in the screen design, which scatters each ray from each point of the screen, thus forming a viewing area.

4) The compensation unit consists of a first compensation element 7 and a second compensation element 6. The first compensation element 7 is characterized by zero optical power in the vertical direction and negative optical power in the horizontal direction, thus the first compensation element 7 has a negative field curvature, which is used by the authors of the invention to compensate for the curvature of the viewing area, and the entire wide field of view will be directed towards the observer's eye.

It should be noted that field curvature is an optical aberration of optical systems, see, for example: https://en.wikipedia.org/wiki/Petzval_field_curvature, which they usually try to eliminate in optical systems. By contrast, the shape of the first compensation element 7 with a negative field curvature is used by the present invention to compensate for the curvature of the field of view.

Due to the negative optical power in the horizontal direction of the first compensation element 7, the rays related to the edges of the image have large angles of incidence on the retroreflector 3, so some of them cannot be reflected from it in the same direction, so some of the light and image may be lost. To convert these larger angles into smaller ones that will be reflected correctly, i.e. horizontally in the same direction in which they fell on the reflector, and vertically as from a conventional mirror, and with high efficiency, the second compensation element 6 is used, which is characterized by zero optical power in the vertical direction and positive optical power horizontally.

Thus, radiation from the projector 2 in a certain range of angles falls on the first compensation element 7, the rays passing in the center of the field of view pass without changes through the redirecting optical element 5, the optical light-scattering element 4 and fall on the retroreflector 3, then are reflected from it into in the same direction horizontally, the optical light-scattering element 4 again passes through, where they are scattered in the vertical direction, and the redirecting optical element 5, where they are redirected from the dead viewing zones to the useful one and enter the observer’s pupil, see the rays indicated by dots in Fig. 10A . In this case, the rays (rays indicated by solid or dotted lines) related to the edges of the image pass through the first compensation element 7, which has a negative optical power in the horizontal direction, and exit the first compensation element 7 at large angles, then the rays pass through the redirecting element 5 and optical light-scattering element 4, practically without changing the direction of propagation, and fall on the second compensation element 6, which is characterized by zero optical power in the vertical direction and positive optical power horizontally and is designed in such a way that rays at large angles are converted into smaller angles and then fall on the reflector 3, are reflected from it in the same direction horizontally and as from a conventional mirror vertically, pass the second compensation element 6, upon exiting which the rays at small angles are converted into large angles and then fall on the optical light-scattering element 4 , which scatters radiation in the vertical direction, then hits the redirecting optical element 5, which ensures the redirection of rays falling into the dead viewing zones into the useful viewing area, and then passes through the first compensation element 7, while the rays passing in the center of the compensation element 7, pass through unchanged, and edge rays at large angles are converted to smaller angles and enter the useful viewing area without distortion.

FIG. 10B shows a diagram of rays entering the pupil of the eye, where it is clearly seen that the central and side rays, indicated by dots, solid or dotted lines in FIG. 10A, enter the observer's pupil.

In fig. 11A shows a radiation intensity distribution map for a 3D image forming device without a compensation block, obtained on a detector in the form of a square, 300×300 mm in size (-150:+150), located at a distance of 500 mm from the screen (consisting of a retroreflector 3, optical light-diffusing element 4, redirecting optical element 5), while the angle between the optical axis of the projector and the optical axis of the screen is 40 degrees. In this case, the values along the X, Y axes in Fig. 11A represent the coordinates of the detector, and the radiation intensity scale (I) next to the detector shows the intensity of any point and its position on the detector, i.e. intensity distribution.

FIG. 11B is a cross-sectional graph of the radiation intensity distribution map of FIG. 11A, where the X-axis is the detector coordinate values along the X-axis, and the Y-axis is the intensity values (I).

In this case, the width of the viewing area created by the 3D image forming device without a compensation element is 15 mm, i.e. not the entire image falls into the pupil of the observer's eye (the pupil of the observer's eye is 2-5 mm depending on the lighting).

In fig. 11C shows a radiation intensity distribution map for a device for forming a multi-angle 3D image with a compensation block obtained on a detector in the form of a square, 300×300 mm in size (-150: +150), located at a distance of 500 mm from the screen (consisting of a retroreflector 3, optical light-scattering element 4, redirecting optical element 5), and the angle between the optical axis of the projector and the optical axis of the screen is 40 degrees. In this case, the values along the X, Y axes in Fig. 11C represent the coordinates of the detector, and the radiation intensity scale (I) next to the detector shows the intensity of any point and its position on the detector, i.e. intensity distribution.

FIG. 11D is a cross-sectional graph of the radiation intensity distribution map according to FIG. 11C, where the X-axis is the detector coordinate values along the X-axis, and the Y-axis is the intensity values (I).

In this case, the width of the viewing area created by the 3D image forming device with a compensation element is 4 mm, i.e. the entire image enters the pupil of the observer's eye.

Thus, the presence of a compensation block in the device helps eliminate distortions in the viewing area for horizontal fields, i.e. in the horizontal direction, see Fig. 10A, 10B, where it is clearly illustrated that the viewing areas are deformed along the horizon, and as can be clearly seen in FIG. 10B the entire image falls into the eye of the observer.

Next, options for implementing compensation elements will be presented.

Various optical elements 1) can be used as compensation elements, such as cylindrical lenses, Fresnel lenses, diffraction lenses, holographic lenses, geometric phase lenses, liquid crystal lenses, metalenses.

The inclusion of compensation elements of the above option 1) in the device for forming a multi-angle 3D image simplifies the manufacture of the device, since it is possible to use commercially produced optical elements; these optical elements are suitable for any device configurations.

In one embodiment 2), the compensation elements may be active liquid crystal (LC) lenses. Examples of active LC lenses are disclosed in the publication: https://www.researchgate.net/publication/258813376_Electrically_Tunable_Liquid_Crystal_Lenses_and_Applications

The inclusion of active LC lenses of the above option 2) in the device for forming a multi-angle 3D image allows you to actively correct the distortion of the viewing area, but at the same time, the production of such optical elements is complicated by the large dimensions of these elements, which requires more developed production technologies to achieve high precision in production .

In yet another embodiment 3), the compensation elements can be a combination of the properties of various optical elements in one element. The inventors are considering the possibility of combining various functions of optical elements in a single optical element, for example, combining an optical light scattering element configured to scatter in the vertical direction and a compensation element into a compensation element with an additional function of scattering in the vertical direction.

The inclusion of compensation elements with combined functions in the device for forming a multi-angle 3D image, for example, with the function of an optical light-scattering element according to option 3) reduces the number of elements composing the device and significantly reduces the thickness of the device, but at the same time, optical elements with combined functions are themselves more complex in itself, which requires more advanced production technologies.

In another embodiment 4), the role of compensation elements is played by a screen (screen block), which is characterized by curvature in the horizontal direction. In fig. 12A, shows a variant of a curved/curved screen of a device for forming a multi-angle 3D image according to the invention, consisting of a retroreflector 3, an optical light-scattering element 4 and a redirecting optical element 5; Fig. 12A also conventionally shows one projector, although the number of projectors can be 2 or more depending on the number of VZ viewing zones formed. In this embodiment, the function of compensating for distortion of the viewing area in the horizontal direction is fully or partially performed due to the curvature of the components that make up the screen unit: retroreflector 3, optical light-diffusing element 4, configured to scatter light reflected from the retroreflector 3 in the vertical direction relative to the eye of the observer redirecting the optical element 5 in the horizontal plane. In this case, when the compensation function is partially performed due to the curvature of the constituent optical components of the screen, the compensation block (the first and second compensation elements) are still present in the structure, but have a different (smaller in magnitude) optical power in the corresponding directions.

The inclusion of a screen with a compensation element function in the device for forming a multi-angle 3D image according to option 4) is characterized by a new ergonomic design, which allows you to turn your head less when viewing the generated image and the effect of complete immersion (immersion effect), which is usually used in planetariums (images are viewed on a round roof). But in some cases of using display technology (too small a distance or too large a distance from the screen to the user), the curvature may be too large (the screen will be a hemisphere), which is already inconvenient, not ergonomic, and not aesthetically pleasing. In addition, the presence of optical elements of complex shape that form a curved screen is due to the difficulties of manufacturing such a screen, which requires more advanced production technologies.

In another embodiment 5), the compensation elements have additional optical coatings for various purposes, for example: anti-reflective coatings to increase the transmittance of the surfaces of optical elements that transmit radiation, reflective coatings to increase the reflectance of surfaces that reflect radiation, filter coatings to filter out unwanted radiation for the operation of the device, as well as beam splitting coatings. The specified coatings are used depending on the required tasks.

The inclusion of compensation elements with coatings in the device for forming a multi-angle 3D image according to option 5) allows for increased flexibility when designing a device for forming a 3D image, due to the fact that a number of optical coatings have special properties and allow very diverse work with light. Due to this property of optical coatings, those skilled in the art can select the desired target parameters of the 3D imaging device being designed from a wide range of options, i.e. At the same time, there is greater flexibility in choosing the required parameters. At the same time, the described compensation elements with coatings are more complex in themselves, which requires more developed production technologies.

Next, we will consider possible options for the layout of projectors used in a device for forming a multi-angle 3D image of a projection type, which is an autostereoscopic or holographic image.

A. Obtaining an autostereoscopic image.

It should be noted that the generated 3D image can be obtained by means of a block of projectors that project views of the 3D image/scene onto the screen and form viewing areas of the autostereoscopic image, causing the illusion of volume, that is, a feeling of relief and extension in depth due to the features of binocular vision, in the user , who placed the pupils of his eyes in the appropriate viewing areas, without the use of additional wearable devices.

For the autostereoscopic projection method, at least two traditional projectors known from the prior art are used: https://en.wikipedia.org/wiki/Projector, located at a distance corresponding to the interocular distance of the user at a certain distance to the screen, i.e. depending on the purpose of the system (home/public cinema), and where each of the projectors creates a viewing area in which the user's eye will see one 2D image.

B. Obtaining a holographic image

A holographic projection device produces a 3D image by reconstructing the wavefront of the displayed object (scene), in which the holographic image is projected onto the screen.

In this case, the generated 3D image can be obtained by means of a block of holographic projectors, which project a holographic image/scene onto the screen and form viewing areas for the holographic image, i.e. viewing zones in each of which the user, who placed the pupils of his eyes in the corresponding viewing zone, will see the full reconstructed wavefront from a real object/scene, which contains all the signs of a 3D object/scene, without the use of additional wearable devices.

In this case, at least one holographic projector is used, known from the prior art: https://sciencing.com/holographic-projectors-work-12226294.html, creating one viewing area when located in which the user’s eye will see the full reconstructed wavefront from the real object /scenes.

According to an embodiment of the invention, the device for forming a multi-angle 3D image additionally contains a line of switchable lenses, i.e. a set of spatially spaced lenses, representing objectives, with the ability to direct radiation from a radiation source, which is a projector without a lens-objective, into any lens from a set of switchable lenses.

It should be noted that very often for various purposes it is necessary to increase the number of viewing areas, but to implement this task it is necessary to increase the number of projectors, which is expensive. To maintain the number of projectors with a minimum configuration (1-2), the applicants propose to use a line (set) of switchable lenses (lenses) optically coupled with at least one projector to form two or more viewing areas. Thus, the number of generated viewing areas increases while maintaining the same number of projectors. In fig. 12B is a diagram of a multi-view 3D generating apparatus according to the invention, wherein a switchable lens array 8 is optically coupled to at least one projector 2 to form two or more viewing zones VZ.

It should be noted that the switchable lens line contains at least two lenses.

In this case, the switchable lens in the line 8 of switchable lenses is a lens configured to transfer the image formed by at least one projector 2 to the screen unit (3+4+5+6+7) to form at least one viewing area VZ . In this case, the screen block contains a retroreflector 3, an optical light-scattering element 4, a redirecting optical element 5 and a compensation block (6,7), optically coupled with at least one projector 2 and with at least one pupil of the observer.

In this case, the device additionally contains a tracking device 9, configured to track the position of at least one of the user's eyes or pupils and ensure that the image is output to the corresponding viewing area. These tracking devices (trackers) are known from the prior art, see, for example, the publication: https://ru.wikipedia.org/wiki/TrackIR

The tracking device 9 is configured to connect with at least one projector 2 and a line 8 of switchable lenses. In this embodiment, the light from the radiation source, in this case the projector 2, has the ability to hit any lens in a line of 8 switchable lenses, each of which will transfer it to the screen, which will form the viewing area VZ. In this way, an increase in the number of zones is achieved with the same number of radiation sources, the function of which is performed by projector 2.

In addition, the device is also provided with a control unit (not shown) connected to at least one projector 2, a tracking device 9 and a line of switchable lenses 8 to control each of these units and ensure synchronization of the operation of these units. For example, in this embodiment, the tracking device 9 of the user's head position transmits the coordinates of the user's head position to the control unit, which, based on the received data (coordinates), displays an image corresponding, for example, to an angle, view of a three-dimensional object or scene based on the position of the user's head , into the projector 2 and sends a signal to the line of 8 switchable lenses to activate the lens (lens) corresponding to the coordinates of the position of the user’s head, and accordingly, other lenses in the line of 8 switchable lenses are not activated, while the activated lens (lens) transfers radiation from the projector 2 to the screen block (3+4+5+6+7), which forms the VZ viewing area corresponding to the current coordinates of the user’s head position.

In a preferred embodiment, the projectors are spaced apart from the geometric center of the respective viewing area in a vertical plane, and are placed outside the respective viewing area, namely above or below the viewing area. This arrangement of projectors is user-friendly, gives the user freedom in the location of the projection system and is compact. With this arrangement, it is possible to use a tracking device to determine the exact position of the user's head or eyes(pupils).

Various types of radiation sources.

The following radiation sources for the claimed 3D image forming device can be used: digital micromirror display (DMD), liquid crystal on silicon (LCOS) display, laser projectors, LEDs, liquid crystal display (LCD), digital micromirror projection display (DLP) etc.

In yet another embodiment, all optical elements of the screen unit of the device according to the invention have additional optical coatings for various purposes, for example: anti-reflective coatings to increase the transmittance of the surfaces of optical elements that transmit radiation, reflective coatings to increase the reflectance of surfaces that reflect radiation, filter coatings to filter unwanted radiation for device operation, as well as beam splitting coatings. The specified coatings are used depending on the required tasks.

The inclusion of coated optical elements in a device for forming a multi-angle 3D image allows for increased flexibility in designing a device for forming a 3D image, due to the fact that a number of optical coatings have special properties and allow for very diverse work with light. Due to this property of optical coatings, those skilled in the art can select the desired target parameters of the 3D imaging device being designed from a wide range of options, i.e. At the same time, there is greater flexibility in choosing the required parameters. At the same time, the described coated optical elements are highly complex in themselves, which requires more advanced production technologies.

Industrial applicability

A device for generating multi-view three-dimensional (3D) images, such as autostereoscopic or holographic images for one or more users, can be used for educational, advertising and entertainment purposes at home, as well as in public places, for example, cinemas, museums, educational institutions, where there is a need to generate multi-view, color 3D images.

Claims (42)

1. A device for forming a multi-angle three-dimensional (3D) projection type image, containing: at least one projector configured to form an image in a corresponding viewing area, wherein each of the at least one projector is spaced from the geometric center of the corresponding viewing area in a vertical plane relative to the eyes of the observer, and is located outside the corresponding viewing area, a screen unit having a spatial distribution function of scattering and/or a spatial distribution function of reflection, and configured to form at least one viewing area of the generated image, wherein the screen block contains a retroreflector, an optical light-scattering element, a redirecting optical element and a compensation block, optically coupled with at least one projector and with at least one pupil of the observer's eye, a retroreflector is a reflective film made in the form of a set of one-dimensional rectangular prisms, elongated in the vertical direction relative to the eyes of the observer, with a reflective coating on the edges of the prisms, an optical light-scattering element is located next to the retroreflector along the direction of radiation emitted from at least one projector, and is configured to scatter the light reflected from the retroreflector in a vertical direction relative to the eyes of the observer, the redirecting optical element has a spatial scattering distribution function and/or a spatial reflection distribution function, and is configured to redirect radiation, when reflected from the retroreflector and passing through the optical light-scattering element, to the area of at least one viewing zone in which the observer's eye is located when in use devices, wherein said redirecting optical element is made with an offset optical axis relative to the optical axis of the device, and is characterized by zero optical power in the horizontal direction and a preset optical power (OP) in the vertical direction relative to the eyes of the observer, which is inversely proportional to the distance from the screen unit to the at least one corresponding viewing area, the compensation unit is configured to compensate for distortion of at least one corresponding viewing area in the horizontal direction, wherein the compensation block contains a first compensation element and a second compensation element, the first compensation element is located next to the redirecting optical element along the direction of radiation emitted from at least one projector and is characterized by zero optical power in the vertical direction in relation to the eyes of the observer and negative optical power in the horizontal direction in relation to the eyes of the observer, the second compensation element is located between the retroreflector and the optical light-scattering element along the radiation emitted from at least one projector and is characterized by zero optical power in the vertical direction relative to the eyes of the observer and positive optical power in the horizontal direction relative to the eyes of the observer. 2. The device according to claim 1, in which the retroreflector, made in the form of a set of one-dimensional rectangular prisms elongated in the vertical direction with a reflective coating on the faces of the prisms, additionally contains an absorbing coating on the ribs at the tops and/or bases of the prisms to ensure reflection of radiation from the at least one projector without loss of light scattering in the horizontal direction relative to the eyes of the observer, caused by the scattering of light on the edges of the prisms at the tops and/or bases and the scattering and absorption of radiation within the material of the prisms. 3. The device according to claim 1, wherein the first compensation element having zero optical power in the vertical direction and negative optical power in the horizontal direction is an optical element selected from: a holographic lens, a diffractive lens, a Fresnel lens, a geometric phase lens , metalens. 4. The device according to claim 1, wherein the second compensation element having zero optical power in the vertical direction relative to the eyes of the observer and positive optical power in the horizontal direction relative to the eyes of the observer is an optical element selected from: a holographic lens, diffractive lenses, Fresnel lenses, geometric phase lenses, metalenses. 5. The device according to claim 1, in which the redirecting optical element is designed in such a way that it allows each of at least one projector to be spaced apart from the geometric center of at least one corresponding viewing area in a vertical plane relative to the eyes of the observer, and the ability to place each of at least one projector above and/or below the viewing area. 6. The device of claim 1, further comprising a radiation source integrated into each of the at least one projector. 7. The device according to claim 6, in which the radiation source is configured to direct radiation to the screen unit. 8. The device according to claim 1, further comprising a line of switchable lenses optically coupled with at least one projector to form at least one viewing area. 9. The device of claim 8, wherein the switchable lens in the line of switchable lenses is a lens configured to transfer an image generated by at least one projector to a screen unit to form at least one viewing area. 10. Device according to one of paragraphs. 8, 9, further comprising a tracking device configured to track the position of at least one of the user's eyes/pupils. 11. The apparatus of claim 10, wherein the tracking device is configured to connect to at least one projector and a switchable lens array, respectively. 12. Device according to one of paragraphs. 1-11, further comprising a control unit coupled to at least one projector, a tracking device, and a line of switchable lenses. 13. The device of claim 12, wherein the control unit is configured to control at least one projector, a tracking device, and a line of switchable lenses. 14. The device according to claim 1, in which the retroreflector is designed in such a way that the reflection of radiation from at least one projector occurs on the outer surface of the retroreflector, formed by a set of rectangular prisms and being the first surface along the direction of radiation emitted from at least one projector without loss on the scattering of light in the horizontal direction relative to the eyes of the observer. 15. The device according to claim 1 or 14, in which the retroreflector is made in such a way that the period (p) of the retroreflector is the distance between the vertices of adjacent prisms and, taking into account the angular resolution of the observer’s eye, must satisfy the following expression: L⋅ tanω>p> , (1) where ω is the angular resolution of the eye, L is the distance from the screen to the observer, λ is the maximum wavelength from the range of operating wavelengths of the projector, W is the width of the viewing area. 16. The device according to claim 15, wherein the operating wavelength range of the at least one projector is from 400 nm to 700 nm. 17. The device according to claim 1, in which the optical light-scattering element is a holographic diffuser and/or a diffuser made of frosted glass, capable of scattering radiation in the vertical direction relative to the eye of the observer. 18. The device according to claim 1, in which the optical light-scattering element is a diffraction grating of an arbitrary type, where a change in the grating period (p ₁ , p ₂ , ..., p _N ) ensures the formation of an expanded viewing area in the vertical direction. 19. The device according to claim 1, in which the light-scattering optical element is one of: a holographic lens array, a geometric phase lens array, a metalens array, with the ability to scatter light in the vertical direction. 20. The device according to claim 1, in which the light-scattering optical element is an array of two-dimensional lens elements consisting of a set of lenses located along the X and Y axes, with the ability to provide light scattering in the vertical direction and, if necessary, in the horizontal direction. 21. The device according to claim 1, in which the redirecting optical element has an off-axis parameter (OA), which determines the displacement of the optical axis of the optical redirecting element from the optical axis of the device, which is given by the following relationship: OA~T/2, where OA is the off-axis parameter of the redirecting optical element, T is the distance from the radiation source, which is at least one projector, to the eye of the observer. 22. The device of claim 21, wherein the redirecting optical element is an optical element selected from: a holographic lens, a diffractive lens, a Fresnel lens, a geometric phase lens, a metalens. 23. Device according to one of paragraphs. 1-22, in which at least one of the optical elements of the screen unit: a retroreflector, an optical light-scattering element, an optical redirecting element, the first and second compensation elements, is configured to optionally apply a filter coating to filter unwanted radiation for the operation of the device; a reflective coating to increase the reflectance of the surfaces of optical elements, an antireflective coating to increase the transmittance of the surfaces of optical elements. 24. Device according to one of paragraphs. 1-23, wherein the at least one projector comprises at least two stereoscopic projectors. 25. The device according to claim 24, which is configured to form an autostereoscopic image. 26. Device according to one of paragraphs. 1-23, wherein at least one projector includes one holographic projector. 27. The device according to claim 26, which is configured to form a holographic 3D image.