CN111338195A - Vector holographic imaging display system - Google Patents

Abstract

The present application relates to a vector holographic imaging display system, including a laser, a beam expanding and collimating component, a 4f optical system, a first polarizer, and a CCD camera arranged in sequence along the light transmission direction, wherein the 4f optical system includes a 4f optical system along the optical transmission direction. directional spatial light modulator, a first lens, a spatial filter, a second lens and a Ronchi grating; the beam expansion and collimation component includes a pinhole filter and a third lens, the spatial light modulator includes a holographic grating, the holographic The grating is loaded with additional amplitude information and phase information, and the holographic grating carries more than two kinds of optical information. The vector holographic imaging display system of the present application can realize the reproduction of holograms containing more complex and completely different information, and provides a new method and approach for generating rich hologram display; at the same time, the vector holographic imaging of the present application The display system is simple to operate, easy to master, low cost and widely used.

Description

A vector holographic imaging display system

technical field

The present application belongs to the technical field of holographic display, and in particular relates to a vector holographic imaging display system.

Background technique

Holography is a method claimed by Gabor in 1948 in which not only the amplitude but also the phase of the light field can be recorded. The word "holography" combines parts of two Greek words: holos (meaning "completeness") and graphein (meaning "writing or recording"), holography refers to the recording of complete information.

Thus, in the holographic process, the recording medium records the original complex amplitude, ie the amplitude and phase of the complex amplitude of the object wave. The result of the recorded intensity changes is now called a hologram. When the hologram is appropriately illuminated later, our eyes observe the intensity produced by the same complex field.

Once the exact complex field is recovered, we can observe the original complex field at a later time. The restored complex domain preserves the entire disparity and depth information like the original complex domain and is interpreted by our brain as the same 3D object.

SUMMARY OF THE INVENTION

The purpose of the present application is to provide a vector holographic imaging display system, which can generate holograms carrying different information simultaneously.

The technical solution adopted by the present application to solve the technical problem is: a vector holographic imaging display system, which includes a laser, a beam expanding and collimating component, a 4f optical system, a first polarizer and a CCD camera arranged in sequence along the light transmission direction, wherein , the 4f optical system includes a spatial light modulator, a first lens, a spatial filter, a second lens and a Ronchi grating along the optical transmission direction; the beam expansion and collimation component includes a pinhole filter and a third lens, the spatial The optical modulator includes a holographic grating loaded with additional amplitude information and phase information, and the holographic grating carries more than two types of optical information.

Among them, the CCD is a charge-coupled device.

Wherein, the holographic grating includes a holographic grating for selecting the light signal of the appearing pattern, letter or Chinese character.

The holographic grating is a computational holographic grating generated by a computer using a transmittance function, and the transmittance function of the holographic grating is t(x,y)=1/2+γ[a _x (x,y)cos (2πf ₀ x)+a _y (x,y)cos(2πf ₀ y)]/4, where t _(x,y) is the transmittance, f ₀ is the spatial frequency of the holographic grating, γ is the modulation depth, a _x (x, y), a _y (x, y) are the additional information amplitude distributions applied to the horizontal and vertical holographic gratings, respectively.

Wherein, the light emitted by the laser undergoes first-order diffraction through the spatial light modulator, and the first-order diffraction generates four light beams, and the four light beams are respectively ± ± α _x (x, y) on the x-axis. 1st Diffraction Order, ±1st Diffraction Order carrying a _y (x, y) on the y-axis.

Wherein, the spatial filter includes a first opening part arranged along the x-axis and a second opening part arranged along the y-axis, the x-axis and the y-axis are perpendicular, and the x-axis and the y-axis are perpendicular to the the direction of light transmission.

As one of the preferred solutions, the spatial filter includes a second polarizer and a third polarizer, the first opening is provided on the second polarizer, and the second opening is provided on the third polarizer On the film, the second polarizer and the third polarizer are orthogonally arranged and attached to form the spatial filter.

As another preferred solution, the spatial filter includes a first quarter-wave plate and a second quarter-wave plate, and the first opening is disposed on the first quarter-wave plate, The second opening is arranged on the second quarter-wave plate, and the first quarter-wave plate and the second quarter-wave plate are orthogonally arranged and attached to form the spatial filter.

Wherein, the spatial light modulator is located on the front focal plane of the first lens, the spatial filter is arranged on the back focal plane of the first lens, and the spatial filter is a part of the second lens. Fourier plane, the Ronchi grating is located on the back focal plane of the second lens. Wherein, the focal lengths of the first lens and the second lens are equal, and both are f.

Wherein, the angle of the first polarizer relative to the light transmission direction can be adjusted, and by adjusting the angle of the polarizer, the reproduced image of the hologram capturing different amplitude information in the CCD camera can be controlled.

Further, the display system further includes an angle adjustment mechanism, the angle adjustment mechanism is connected with the first polarizer, and is used for adjusting the angle of the first polarizer.

Further, the display system further includes a diaphragm, the diaphragm is arranged between the beam expanding and collimating assembly and the spatial light modulator, and the diaphragm is used to filter the beams emitted by the beam expanding and collimating assembly. Straight beam to obtain a uniform spot of outgoing light.

Further, any numerical hologram can be loaded on the spatial light modulator.

Further, the vector holographic imaging display system of the present application can simultaneously generate two kinds of different light information or one of the two kinds of light information.

Further, wherein the intensity of each information can be along the x-axis in the spatial filter, the y-axis separates the second polarizer and the third polarizer that are orthogonal after the first opening and the second opening, or the positive The relative angle between the first quarter-wave plate and the second quarter-wave plate and the polarization direction of the first polarizer is regulated.

Further, the computational hologram of the additional amplitude and phase information loaded by the spatial light modulator can also be etched into a grating containing the required information according to actual requirements, which is used to display specific complex optical information, so as to make an independent display device. .

Beneficial effects:

In the vector holographic imaging display system of the present application, any numerical hologram can be loaded on the holographic grating, more than two kinds of optical information can be loaded on the holographic grating, and the intensity of the optical information can be adjusted by adjusting the angle between the first polarizer and the spatial filter to achieve more For the reproduction of complex holograms with completely different information, in order to be able to generate rich holograms; the vector holographic imaging display system of the present application is used to display specific complex light information, so as to make an independent display device, the reproduction of The holographic light information can contain more than two kinds of information, and can selectively display different information, including information intensity, type and number, and can generate holograms carrying different information at the same time; at the same time, the vector holographic imaging display system of the present application Simple operation, easy to master, low cost and wide application.

Description of drawings

FIG. 1 is a schematic diagram of the light information of the first embodiment captured by the CCD camera of the vector holographic imaging display system of the present application;

FIG. 2 is a schematic diagram of the light information of the second embodiment captured by the CCD camera of the vector holographic imaging display system of the present application;

FIG. 3 is a schematic diagram of light information captured by the CCD camera of the vector holographic imaging display system of the application according to the third embodiment;

FIG. 4 is a schematic structural diagram of an embodiment of the vector holographic imaging display system described in this application.

Among them, 10-laser; 20-beam expansion and collimation component; 30-4f optical system; 50-first polarizer; 60-CCD camera; 11-guide rail; 12-fixable slider; 13-optical bracket; 14- Adjustment knob; 15-optical adjustment rod; 21-pinhole filter; 23-third lens; 31-spatial light modulator; 32-first lens; 33-spatial filter; 34-second lens; 35-lang Odd grating; 341-first opening; 342-second opening.

Detailed ways

The present application will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can refer to the description and implement accordingly.

It should be understood that terms such as "having", "comprising" and "including" as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

A vector holographic imaging display system, as shown in FIG. 4 , includes a laser 10, a beam expanding and collimating component 20, a 4f optical system 30, a first polarizer 50 and a CCD camera 60, which are arranged in sequence along the light transmission direction, wherein all the The 4f optical system 30 includes a spatial light modulator 31, a first lens 32, a spatial filter 33, a second lens 34 and a Ronchi grating 35 along the optical transmission direction; the spatial light modulator 31 includes a holographic grating, and the holographic The grating is loaded with additional amplitude information and phase information, and the holographic grating carries more than two kinds of optical information.

In the vector holographic imaging display system of the embodiment of the present application, any numerical hologram can be loaded through the holographic grating, and the intensity of different optical information can be adjusted by adjusting the angle between the first polarizer 50 and the spatial filter 33 by loading more than two kinds of optical information. , in order to realize the reproduction of more complex holograms with completely different information, in order to be able to generate rich holograms; the vector holographic imaging display system of the present application is used to display specific complex optical information, so as to make an independent display device , the reproduced holographic light information can contain more than two kinds of information, and can selectively display different information, including information intensity, type and number, and can generate holograms that reproduce different information at the same time; The holographic imaging display system is simple to operate, easy to master, low cost and widely used.

The spatial light modulator 31 in the embodiment of the present application may be a digital holographic grating, and the spatial light modulator 31 includes an optical signal for selecting patterns, letters or Chinese characters to appear.

Further, the spatial filter 33 includes a first opening 341 arranged along the x-axis and a second opening 342 arranged along the y-axis, the x-axis and the y-axis are perpendicular, and the x-axis and the y-axis are perpendicular The axis is perpendicular to the light transmission direction. By arranging the first opening 341 and the second opening 342 , the light beam can be diffracted through the first opening and the second opening 342 . In the embodiment of the present application, the x-axis refers to the horizontal direction as shown in FIG. 4 , the y-axis refers to the vertical direction, the z-axis refers to the light transmission direction, and the z-axis is perpendicular to the x-axis and the y-axis.

Specifically, in the embodiment of the present application, the spatial filter 33 includes a second polarizer and a third polarizer, the first opening 341 is provided on the second polarizer, and the second opening 342 is provided On the third polarizer, the second polarizer and the third polarizer are orthogonally arranged and attached to the spatial filter 33 . In other embodiments, the spatial filter 33 may also include a first quarter-wave plate and a second quarter-wave plate, and the first opening 341 is disposed on the first quarter-wave plate , the second opening 342 is arranged on the second quarter-wave plate, the first quarter-wave plate and the second quarter-wave plate are orthogonally arranged and attached to the spatial filter device 33.

Specifically, in the embodiment of the present application, the laser 10 is used to generate a linearly polarized fundamental mode Gaussian beam with a horizontal polarization direction. As a preferred solution in the embodiment of the present application, the laser 10 selects He-Ne with an emission wavelength of 632.8 nm. Laser 10 .

In the embodiment of the present application, the beam expanding and collimating assembly 20 is used to sequentially perform beam expanding and collimating processing on the laser light generated by the laser 10 . Specifically, the beam expanding and collimating assembly 20 in the embodiment of the present application is as close as possible to the laser 10 a little. Among them, in the embodiment of the present application, the beam expansion and collimation assembly 20 includes a pinhole filter 21 and a third lens 23, wherein the pinhole filter 21 is arranged between the laser 10 and the third lens 23, and the pinhole filter 21 It is used for the linearly polarized fundamental mode Gaussian beam emitted by the beam expander laser 10 , and the third lens 23 is used for collimating the linearly polarized fundamental mode Gaussian beam expanded by the pinhole filter 21 .

As another preferred solution of the embodiment of the present application, in order to filter out unnecessary light and obtain a uniform light spot of the outgoing light, a diaphragm (not shown in the figure) is set between the third lens 23 and the spatial light modulator 31. It is used to filter the collimated light beam emitted by the beam expander and collimating component 20, so as to constrain the light beam to obtain a uniform light spot of the outgoing light.

The holographic grating used by the spatial light modulator 31 in the embodiment of the present application is a computational holographic grating HG generated by a computer using a transmittance function. The transmittance function of the given holographic grating is:

t(x,y)=1/2+γ[a _x (x,y)cos(2πf ₀ x)+a _y (x,y)cos(2πf ₀ y)]/4

Among them, t _{(x, y)} is the transmittance, f ₀ is the spatial frequency of the holographic grating, and γ is the modulation depth. a _x (x, y), a _y (x, y) are the additional information amplitude distributions imposed on the horizontal and vertical holographic gratings, respectively.

The light emitted by the laser 10 passes through the beam expanding and collimating component 20 to form a collimated beam and irradiates it to the holographic grating. For the linearly polarized light incident on the holographic grating, its first-order diffraction will generate four beams, which are respectively on the x-axis. Carry the ±1st diffraction order of a _x (x, y) and the ±1st diffraction order of a _y (x, y) on the y-axis.

In the embodiment of the present application, the spatial light modulator 31 is located on the front focal plane of the first lens 32, the spatial filter 33 is located on the rear focal plane of the first lens 32, and the The spatial filter 33 is the Fourier plane of the second lens 34 , and the Ronchi grating 35 is located on the back focal plane of the second lens 34 . The focal lengths of the first lens 32 and the second lens 34 are the same, and both are f. Illumination to the holographic grating passes through the first lens 32 and to a spatial filter 33 which allows passage of the first order diffraction orders of _ax (x,y) and _ay (x,y) on the x- and y-axes , the light emitted by the second lens 34 is combined by the Ronchi grating 35 and reaches the CCD camera 60 through the first polarizer 50 to obtain the target beam matching the fringe shape of the spatial light modulator 31 to generate the image of the target shape in the CCD camera 60 .

The hologram can be loaded onto the spatial light modulator 31 for hologram reconstruction. Computer-generated holograms CGH have the advantage that three-dimensional objects do not have to exist in the real world. That is, the object to be displayed may be fictitious. However, most of the current holographic imaging is based on the scalar light field, which only contains a single polarization state information, that is, only contains one kind of light information. The present application is mainly based on a vector holographic imaging display system containing multiple information storage based on different information carried by two orthogonal polarization states. It can store more than two kinds of information at the same time and selectively display different information, including information intensity, type and number of information.

In order to prevent the CCD camera 60 from capturing extra light intensity distribution outside the axis, in the embodiment of the present application, the distance between the CCD camera 60 and the Ronchi grating 35 is less than or equal to 10 cm.

In the embodiment of the present application, the angle of the first polarizer 50 relative to the light transmission direction can be adjusted, and by adjusting the angle of the polarizer, the reproduction of the holograms that capture different amplitude information in the CCD camera 60 can be controlled image. For example: a computational holographic grating containing amplitude and polarization information loaded on the spatial light modulator 31, wherein the x-axis carries relevant information about the D letter, and the y-axis carries information about the H letter. When the first polarizer 50 is connected to The polarization direction of the first polarizer 50 placed behind the first opening 341 along the x-axis on the spatial filter 33 is consistent, that is, the first polarizer 50 is a horizontal polarizer, as shown in FIG. Information component D in the x-direction. On the contrary, if the polarization direction of the first polarizer 50 is the same as that of the first polarizer 50 placed behind the second opening 342 along the y-axis on the spatial filter 33, that is, the first polarizer 50 is a vertical polarizer, as shown in FIG. 2 . If shown, only the information component H along the y-direction in the input light field is obtained. If the polarization direction of the first polarizer 50 is different from the direction of the first polarizer 50 placed at the first opening 341 and the second opening 342 behind the spatial filter 33 , then the information of the reproduced hologram contains different information. The two kinds of information of D and H of the amplitude, the weight of the light intensity occupied by the specific information component D and the information component H is determined by the first polarizer 50 and the first opening 341 and the second opening 342 after the spatial filter 33. The direction of the second polarizer and the third polarizer is determined. For example, the direction of the first polarizer 50 is exactly the angle between the second polarizer and the third polarizer placed at the first opening 341 and the second opening 342 behind the spatial filter 33 Both are 45°, that is, the polarization direction of the first polarizer 50 is in the middle of the polarization direction of the second polarizer and the third polarizer, then reproduce the superposition of the information carried by the horizontal polarization component and the vertical polarization component as shown in Figure 3 , the superimposed information of the two light intensities of the information component D and the information component H are halved, and so on. The above only shows the case where two orthogonal polarizers are placed behind the spatial filter 33 in the first opening 341 and the second opening 342 . Of course, orthogonal first quarter wave plate and second quarter wave plate can also be placed.

Wherein, in the embodiment of the present application, an angle adjustment mechanism (not shown in the figure) is further included, and the angle adjustment mechanism is connected with the first polarizer 50 for adjusting the angle of the first polarizer 50 . In the embodiment of the present application, the angle adjustment mechanism includes a driving mechanism (not shown) and a rotating mechanism (not shown), and the rotating mechanism is driven to rotate by the driving mechanism to drive the first polarizer 50 to rotate. By controlling the rotation of the first polarizer 50, two or more information components with different light intensities can be formed.

Further, the computational hologram of the additional amplitude and phase information loaded by the spatial light modulator 31 can also be etched into a grating containing the required information according to actual requirements to display specific complex optical information, so as to make an independent display. device. The production process of the digital holographic grating wave plate as the spatial light modulator 31: first, the spatial light modulator 31 or MATLAB is used to simulate the digital holographic grating with specific spacing and fringes, and the digital holographic grating is converted into a binary optical grating by the MATLAB program. Then convert the binary optical grating into a vector diagram that can be used for industrial processing, and then use it to make the reticle required for the grating. Finally, the reticle is attached to the lithography machine, and the JGS1 fused silica is cleaned and glued. , photolithography, etching and other processes to produce digital holographic grating waveplate.

As a further preference of the above-mentioned embodiment, the system further includes a height adjustment component, which includes an optical guide rail 11 , a fixed slider 12 on the guide rail 11 , an optical bracket 13 , an adjustment knob 14 , and an optical adjustment rod 15 . Rotating the knob 14 can drive the adjusting rod 15 to slide up and down along the vertical direction, so as to realize the height adjustment of the above components by the height adjusting assembly. The slider 12 includes several correspondingly fixedly connected below the optical bracket 13 . The slider 12 is slidably connected to the guide rail 11, and drives each device on the height adjustment assembly to move as a whole. Compared with the ordinary optical platform, the distance between the devices can be flexibly and continuously adjusted in the same plane to ensure that the subsequent beams can be adjusted in a continuous manner. Stabilized imaging on CCD camera 60 .

It should be noted here that the laser 10, the beam expanding and collimating assembly 20, the spatial light modulator 31, the first lens 325, the spatial filter 33, the second lens 34, the Ronchi grating 35, the first polarizer 50 and the CCD camera 60 When adjusting the height through the height adjustment components, the optical paths of these devices should be on the same horizontal line.

Although the embodiments of the present application have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for this application. Additional modifications can be readily implemented by those skilled in the art. Therefore, the application is not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the claims and the scope of equivalents.

Claims (10)

1. a vector holographic imaging display system, is characterized in that, comprises laser (10), beam expanding collimation assembly (20), 4f optical system (30), the first polarizer (50) arranged successively along the light transmission direction and a CCD camera (60), wherein the 4f optical system (30) comprises a spatial light modulator (31), a first lens (32), a spatial filter (33), and a second lens (34) along the optical transmission direction ) and a Ronchi grating (35); the beam expanding and collimating component (20) includes a pinhole filter (21) and a third lens (23); the spatial light modulator (31) includes a holographic grating loaded with In addition to amplitude information and phase information, the holographic grating carries more than two kinds of optical information. 2 . The vector holographic imaging display system according to claim 1 , wherein the holographic grating contains light information for selecting patterns, letters or Chinese characters to appear. 3 . 3. vector holographic imaging display system according to claim 1, is characterized in that, described holographic grating is the computational holographic grating that utilizes transmittance function computer to produce, and the transmittance function of described holographic grating is t(x, y)=1/2+γ[a _x (x,y)cos(2πf ₀ x)+a _y (x,y)cos(2πf ₀ y)]/4, where t(x,y) is the transparent Over rate, f ₀ is the spatial frequency of the holographic grating, γ is the modulation depth, a _x (x, y), a _y (x, y) are the additional information amplitude distributions applied to the horizontal and vertical holographic gratings, respectively. 4. The vector holographic imaging display system according to claim 3, wherein the light emitted by the laser (10) generates first-order diffraction through the spatial light modulator (31), and the first-order diffraction generates four The four light beams are respectively ±1st order diffraction orders carrying a _x (x, y) on the x-axis, and ±1st order diffraction orders carrying a _y (x, y) on the y axis. 5. The vector holographic imaging display system according to claim 1, wherein the spatial filter (33) comprises a first opening (341) arranged along the x-axis and a second opening (341) arranged along the y-axis (342), the x-axis and the y-axis are perpendicular, and the x-axis and the y-axis are perpendicular to the light transmission direction. 6. The vector holographic imaging display system according to claim 5, wherein the spatial filter (33) comprises a second polarizer and a third polarizer, and the first opening (341) is arranged in the On the second polarizer, the second opening (342) is provided on the third polarizer, and the second polarizer and the third polarizer are orthogonally arranged and bonded to form the spatial filter (33). );or The spatial filter (33) includes a first quarter-wave plate and a second quarter-wave plate, and the first opening (341) is arranged on the first quarter-wave plate, so The second opening (342) is arranged on the second quarter-wave plate, and the first quarter-wave plate and the second quarter-wave plate are orthogonally arranged and attached to form the spatial filter device (33). 7. The vector holographic imaging display system according to claim 1, wherein the spatial light modulator (31) is located on the front focal plane of the first lens (32), and the spatial filter (33) ) is arranged on the back focal plane of the first lens (32), the spatial filter (33) is the Fourier plane of the second lens (34), and the Ronchi grating (35) is located at the the back focal plane of the second lens (34). 8. The vector holographic imaging display system according to claim 1, wherein the angle of the first polarizer (50) relative to the light transmission direction is adjustable, and by adjusting the angle of the polarizer, the The intensity of two or more types of light information is controlled, and the reproduced image of the holograms in the CCD camera (60) that captures information of different amplitudes is controlled. 9 . The vector holographic imaging display system according to claim 1 , further comprising an angle adjustment mechanism, and the angle adjustment mechanism is connected to the first polarizer (50) for adjusting the first polarization. 10 . The angle of the sheet (50). 10 . The vector holographic imaging display system according to claim 1 , further comprising a diaphragm, the diaphragm is disposed on the beam expanding and collimating assembly ( 20 ) and the spatial light modulator ( 31 ). 10 . In between, the diaphragm is used to filter the collimated light beams emitted by the beam expanding and collimating components (20), so as to obtain a uniform light spot of the outgoing light.

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