RU5270U1 - INSTALLATION FOR ELECTRONIC FORMATION OF THREE-DIMENSIONAL HOLOGRAPHIC IMAGE - Google Patents

Abstract

1. Installation for electronic formation of a three-dimensional holographic image containing a holographic display, a coherent monochromatic light source and an electronic control element with signal, reference and synchronization blocks, characterized in that the display is made in the form of a plate of photoelastic material, on one of the wide faces of which is a matrix of acoustic emitters connected to the reference and signal blocks of the electronic control element. 2. Installation according to claim 1, characterized in that on one of the wide faces of the plate there is a piezoelectric layer having acoustic contact with the plate, and the matrix of acoustic emitters is made on the piezoelectric layer. The installation according to claim 2, characterized in that the matrix of acoustic emitters is made in the form of two systems of electrodes placed on opposite wide faces of the piezoelectric layer, the electrode systems are periodically arranged strips, and the strips of the electrode system placed on one face of the piezoelectric layer are made perpendicular to the stripes of the system electrodes placed on another face, and the width of the strips is equal to the thickness of the piezoelectric layer.

Description

The utility model relates to acousto-optics and can be used in the development of television and computer systems.

A known installation for forming an electronic three-dimensional holographic image (see R.Zh. Inventions of the countries of the world, issue 90 MKI POS N 12; (19): PCT (WO), (51): 5 G03H 1/26, (71): Graham, Dundas, Richmond, (12): A1 (11): 94/24615, (40): 941027-24, (54): Holograms), intended1; I to display character messages. The installation is made of a matrix of identical holograms, each of which contains all the images necessary for the formation of the displayed information.

The disadvantages of the installation are:

1. The inability to form an arbitrary number of images due to the finite number of holograms included in the matrix.

2. The installation allows you to generate only symbolic messages, due to once embedded information in the form of identical holograms.

Also known is an apparatus for forming an electronic three-dimensional holographic image (see C. Newswanger, Animated holographic stereogram display, US Patent No. 5191449 (March 02.1993). RZH ISM, issue 90 (MKI G03 G, H) N 9, 1994 cnh / 74), comprising a hologram block consisting of a plurality of first and second holographic images and forming a stereo pair of images. The said plurality of first images is superimposed on the first hologram element, and the plurality of second images are superimposed on the second hologram element. Hologram elements are located at a distance from each other and form a hologram block, while the first hologram element can be observed with one eye of the observer, and the second at the same time

the second eye of the same observer. Each pair of images has predetermined adjacent observation zones when illuminated by a point source located in a predetermined position relative to the hologram unit. The observation zone of each pair of images is spatially separated from the observation zone of each other pair of images. The system contains many light sources located with a given spatial ratio relative to the hologram block so that when any of the light sources is turned on, the observer will see the zones of the corresponding pair of images.

The disadvantages of this installation are:

1. Discretization of the replaced images due to discreteness of the observation zones.

2. Each three-dimensional image in such a device is formed by a pair of images and, in fact, is stereoscopic pseudo-volume.

The closest in technical essence to the claimed one is the installation for forming an electronic three-dimensional holographic image using acoustic radiation (JARobillard Detection panel and method for acoustical holography, US Patent No. 4.905.202 (Feb 27.1990) .- РЖ ИСМ (MKI G03G , H) issue 90, N 5, 1991, p. 27). The installation is a flat screen with a liquid crystal layer, which receives acoustic waves reflected from the object. Light radiation incident on a liquid crystal layer is subjected to amplitude and phase modulation due to variations in the refractive index on the surface of this layer. A three-dimensional holographic image is formed using a modulated light beam reflected from the surface of the liquid crystal layer.

The main disadvantage of such an installation is the need for imaging, irradiating the object with acoustic waves, which limits its scope.

Another disadvantage is the large inertia of image formation.

The aim of the proposed solution is to expand the scope of the device (including the creation of moving television or computer images) while reducing the inertia of image formation.

This goal is achieved by the fact that in the installation for generating an electronic three-dimensional holographic image containing a holographic display, a coherent monochromatic light source and an electronic control element with signal, reference and synchronization blocks, the display is made in the form of a plate of photoelastic material, on one of the wide faces of which is a matrix of acoustic emitters connected to the reference and signal blocks of the electronic control element

In addition, the essence of the technical solution is the embodiment of the installation for electronic formation of a three-dimensional holographic image, in which, on one of the wide faces of the plate, there is a piezoelectric layer having acoustic contact with the plate, and the matrix of acoustic emitters is made on the piezoelectric layer.

The essence of another embodiment of the installation for the electronic formation of three-dimensional holographic images is that the matrix of acoustic emitters is made in the form of two systems of electrodes placed on opposite wide faces of the piezoelectric layer, the electrode systems are periodically arranged strips, strips of the electrode system placed on one face of the piezoelectric layer, made perpendicular to the strips of the electrode system placed on another face, and the width of the strips is equal to the thickness of the piezoelectric layer . 3

The essence of the fourth variant of the claimed installation is that the plate is made of piezoelectric material, and the acoustic emitters are piezoelectric transducers of surface acoustic waves.

Signs similar to those claimed in the well-known author of scientific and technical literature are absent.

The claimed solution is illustrated by drawings. On figl, 2 and 3 shows a diagram of the installation for electronic formation of a three-dimensional holographic image, figure 4 is a diagram explaining the principle of forming a three-dimensional holographic image. The apparatus for generating a three-dimensional holographic image comprises a holographic display (1), a coherent monochromatic light source (2) with forming optics (2a), and an electronic control element with signal units (3), reference (4) and synchronization block (5) with synchronizing modulator (5a), the holographic display (1) is made in the form of a plate (6) of photoelastic material on one of the wide faces of which there is a matrix of acoustic emitters (7) connected to the signal (3) and reference (4) blocks of the elec throne control.

In another embodiment of the technical solution (Fig. 2), in addition, on one of the wide faces of the plate, there is a piezoelectric layer (8) having acoustic contact with the plate (6), and the matrix of acoustic emitters (7) is made on the piezoelectric layer (8).

In the third embodiment of the installation (Fig. 3), the matrix of acoustic emitters (7) is made in the form of two systems of electrodes (9) and (10) located on opposite wide faces of the piezoelectric layer (8), the system of electrodes (9) and (10) are periodically arranged strips, strips of the electrode system (9) placed on one face of the piezoelectric layer (8) are made perpendicular to the strips of the electrode system (10) placed on the other face, and the width of the strips (9) and (10) is equal to the thickness of the piezoelectric layer

In the fourth embodiment of the technical solution, the plate (6) is made of

piezoelectric material, and acoustic emitters (7)

are surface piezoelectric transducers

acoustic waves.

In FIG. 4. also shown reproducible and visible

The inventive installation operates as follows. The holographic display (1) is made in the form of a plate (6) made of a photoelastic material in which diffraction of light by acoustic vibrations generated by acoustic emitters is possible (7). The matrix of acoustic emitters controlled from the signal (3) and reference (4) block of the electronic control element excites acoustic vibrations in the photoelastic plate (6), which create an interference pattern of two interacting acoustic fields: signal - controlled from the signal block (3) and reference controlled from the support block (4). This interference pattern corresponds to the interference pattern of two interacting optical fields: the field of the reference light beam and the field of the object light beam reflected from the object (12). The electronic control element of the installation contains a coordinate scaling algorithm that takes into account the difference in the lengths of light and acoustic waves. Thus, the generated acoustic field is an acoustic dynamic hologram containing information about the object (12). When illuminating such a hologram (holographic display (1)) with a source of coherent monochromatic light (2), the observer (11) sees a real three-dimensional holographic image of the object (12). The electronic control element of the device (3), (4), (5) generates a dynamic hologram in the form of a frame having a duration determined by the resolution of the holographic display (1), which, in turn, depends on the speed of acoustic waves in the photoelastic plate material ( 6). The frame repetition rate, determined by the propagation time of the sound wave from the beginning to the end of the holographic display (1), is set by a modulator (5a) controlled from the synchronization unit (5). The modulator (5a) and the synchronization unit (5) generate backlight pulses that are synchronized with the moment of formation of the full frame on the holographic display (1). Coherent monochromatic light from a source (2), modulated by backlight pulses by a modulator (5a) with a synchronization unit (5) is directed to a holographic display (1) at a Bragg angle determined at the center frequency of the working range of the piezoelectric emitters (7), relative to the wide edge of the plate ( 6). The actual three-dimensional holographic image will be visible to the observer (11) with

the opposite side of the display (1) from the light source (2) is also at a Bragg angle to the indicated plane. The Bragg diffraction mode is characterized by only one diffraction order, as a result of which, other diffraction orders will not be observed. The use of a matrix of acoustic emitters compared, for example, with a line of emitters, allows you to enter another coordinate in the acoustic field of the generated dynamic hologram, which simplifies the formation of an algorithm for controlling electrical signals.

The linear size of acoustic emitters (7) is equal to half the length of the acoustic wave in the photoelastic plate (6), and the lattice period is approximately two acoustic wavelengths in the plate (6) and, along with the speed of sound in the plate (6), determines the resolution of the display ( 1) in one of the coordinates. The resolution of the display (1) in a different coordinate is determined by the lattice period of the elements in the emitter matrix (7).

The algorithm for creating control electric signals can be created, for example, by spatiotemporal decomposition of an acoustic field induced in an elasto-optical material by an interference pattern created by pulses of two coherent optical waves - a reference and a signal - reflected from a real object.

In another embodiment of the proposed technical solution, on one of the wide faces of the plate (6) there is additionally a piezoelectric layer (8) having acoustic contact with the plate (6), and the matrix of acoustic emitters (7) is filled on the piezoelectric layer (8), so that the matrix emitters generates acoustic waves that can propagate directly in the piezoelectric layer (8).

In the third version of the proposed technical solution, the matrix of acoustic emitters (7) is made in the form of two systems of electrodes (9) and (10) placed on opposite wide faces of the piezoelectric layer (8), the electrode systems are periodically arranged strips, strips of the electrode system (9) located on one face of the piezoelectric layer (8) are made perpendicular to the strips of the electrode system (10) placed on the other face, so that acoustic vibrations are excited by the regions of the piezoelectric layer formed by overlapping sections and stripes. Such a system for connecting radiating elements makes it possible in a simple way to select the necessary combinations for switching on acoustic emitters.

In the fourth embodiment, the plate (6) is made of a piezoelectric material. In this case, acoustic emitters are electrodes located on the surface of a piezoelectric plate (6). One of the options for this design is the implementation of the acoustic emitters by electrodes exciting surface acoustic waves, for example, by interdigitated structures. It is also possible to combine solutions according to claim 4 and claim 3, when the plate (6) is both a photoelastic material and also serves as a piezoelectric layer (8), so that acoustic vibrations propagate in such a layer as in a waveguide. The implementation of the matrix of acoustic wave emitters by arrangement on the opposite surfaces of the piezoelectric layer (8) (which is also a photoelastic material (6)) of two mutually perpendicular systems of parallel electrodes in the form of strips allows one to obtain some energy gain, eliminating the need to transform acoustic vibrations from one medium to another. This approach also removes the restriction on the size of the display associated with the need to use as photo-elastic crysalic material, which is usually limited in size. Another advantage of this solution is the possibility of using planar thin-film technologies, which can be of economic importance in mass production.

Examples of specific performance of the proposed solutions. The effective operation of the proposed device involves the use of a photo-elastic material having a low acoustic attenuation and a high value of the coefficient of elastic-optical quality. Of the materials known today, such material for the manufacture of a laboratory sample of a holographic display can be, for example, a lithium niobate crystal, which is widely used in the visible range of acoustooptics, as a material with relatively low acoustic attenuation and a relatively high coefficient of acousto-optical quality. Today's technological base allows you to grow lithium niobate crystals with a working section area not exceeding approximately 4x4 cm. The holographic display (1) of the demonstration model of the inventive installation can be made from a plate (6) X-section of lithium niobate with a piezoelectric layer (8) from + 36 ° section of the same crystal placed on a wide face of the plate (6). To excite wide-aperture acoustic fields, the dimensions of the linear apertures of the radiating elements (7) should be approximately equal to half the length of the acoustic wave in the sound duct (in the plate (6)).

The central frequency of the working range of acoustic emitters (7) is chosen equal to 60 MHz, and the working frequency band of frequencies is 20 MHz; in this case, the working frequency band determines the depth of the possible observed object dimensions (12) in the third coordinate (perpendicular to the display plane). Then the linear aperture of the radiating element (7) is approximately 50 microns, and (of the rows and lines of the matrix) is 200 microns. Points with equal phases of two fronts of acoustic waves emitted simultaneously by two adjacent transducers (7) will be separated from each other by a distance equal to the distance between these transducers (7), i.e., at a distance of 200 microns. Thus, the spatial resolution of the display in one of the coordinates is 200 microns. To obtain the same resolution in a different coordinate lying in the plane of the display (1), the duration of the backlight pulse generated by the modulator (5a) and the synchronization unit (5) should be approximately 50 nanoseconds. In addition to the duration of the backlight, the spatial resolution along this coordinate determines the speed of the elastic wave in the photoelastic material. Thus, a resolution of 200 microns in the specified coordinate can be obtained, for example, with a backlight pulse of 0.5 microseconds if a paratellurite crystal is used as the material of the holographic display , and the transducers (7) excite shear acoustic waves.

An example of a specific implementation of another variant of the proposed technical solution is a device for forming an electronic three-dimensional holographic image, in which a film of zinc oxide, which is a piezoelectric and forms a piezoelectric layer, is sprayed on one of the wide faces of a plate (6) of lithium niobate (8). A matrix of acoustic wave emitters (7) is placed on the piezoelectric layer (8).

In the third embodiment of the proposed installation on a photoelastic substrate - a plate (6), the first system of parallel strips (9) is sprayed at the beginning. Then, a film of a piezoelectric, for example, lithium niobate - a piezoelectric layer (8) is sprayed on top of the strips (9). A second system of parallel strips (10) located perpendicular to the strip system (9) is sprayed on top of the piezoelectric layer (8). The overlapping regions of the strips (9) and (10) are emitters of acoustic waves (7). To ensure high divergence of each of the emitted acoustic waves, which, when interacting with each other, create an interference pattern of a dynamic hologram, the width of the strips is chosen equal to half the length of the acoustic wave in the plate (6). The thickness of the piezoelectric layer (8) is chosen equal to half the wavelength of sound in the piezoelectric (8).

If the velocities are equal in piezoelectric (8) and in the plate (6), the width of the strips (9) and (10) is equal to the thickness of the piezoelectric layer (8). An example of a specific implementation of the fourth embodiment of the proposed technical solution is the installation in which the plate (6) is made of a piezoelectric material - lithium niobate YZ + 36, and the acoustic emitters (7) are interdigital transducers of surface acoustic waves.

A three-dimensional holographic image is restored by illuminating the holographic display (1) with coherent monochromatic light incident at a Bragg angle to the wide edge of the plate (6). The observer (11) can also see the three-dimensional image at the Bragg angle to the wide face of the plate (6) from the opposite side of the holographic display (1) from the light source (2). The main advantage of this technical solution is the possibility of creating screens of sufficiently large sizes, as well as the possibility of using planar thin-film technology, which is economically advantageous for mass production.

The proposed installation for forming an electronic three-dimensional holographic image can be used to create moving television or computer three-dimensional holographic images, which expands the scope of its application in comparison with the prototype.

Another advantage in comparison with the prototype of the proposed technical solution is to reduce the inertia of image formation. This advantage is due to the fact that in the prototype liquid crystals with high inertia were used as the display material, while in the proposed solution a dynamic hologram is formed by a field of acoustic waves having velocities of the order of 10 m / s. In this case, the frame rate can be much higher than the frequencies used in industrial television.

We clean one of the possible options for registering images for their subsequent restoration using the proposed solution. The algorithm for creating control electric signals for the proposed installation can be created, for example, by spatiotemporal decomposition of an acoustic field induced in an elasto-optical material by an interference pattern created by pulses of two coherent optical waves - a reference and a signal - reflected from a real object.

Information about the registered object, obtained in this way by a matrix of acoustic receivers similar to the matrix of acoustic emitters (7), can either be restored using the proposed setup in real time, or transmitted via telecommunication channels, or recorded on known storage media.

Compared with the prototype, where it is necessary to irradiate an object with ultrasonic waves, the proposed installation can be used in a wide class of problems where irradiation of an object with ultrasound is impossible or undesirable, which expands the scope of the installation, including the use for creating moving television or computer images. Applicants: Rector of the Saratov State University Academician of the Russian Academy of Sciences, Professor Deputy. Director of NPF Exce at the Saratov State University Author: D.I. Trubetskov L. A. Deryugina. V.V. Petrov

Claims (3)

1. Installation for electronic formation of a three-dimensional holographic image containing a holographic display, a coherent monochromatic light source and an electronic control element with signal, reference and synchronization blocks, characterized in that the display is made in the form of a plate of photoelastic material, on one of the wide faces of which is a matrix of acoustic emitters connected to the reference and signal blocks of the electronic control element.  2. Installation according to claim 1, characterized in that on one of the wide faces of the plate there is a piezoelectric layer having acoustic contact with the plate, and the matrix of acoustic emitters is made on the piezoelectric layer.  3. The installation according to claim 2, characterized in that the matrix of acoustic emitters is made in the form of two systems of electrodes placed on opposite wide faces of the piezoelectric layer, the electrode systems are periodically arranged strips, and the strips of the electrode system placed on one face of the piezoelectric layer are made perpendicular strips of an electrode system placed on another face, and the width of the strips is equal to the thickness of the piezoelectric layer.