Real-time two-mode image display method based on liquid crystal and liquid crystal device

Abstract

The invention provides a real-time two-mode image display method based on liquid crystal and a liquid crystal device.The real-time two-mode image display method based on liquid crystal comprises the steps that the liquid crystal device is constructed, and a rectangular plane coordinate system is established according to the working face of the liquid crystal device; the liquid crystal device has different directors at different positions; placing the liquid crystal device on a frequency spectrum surface of a 4f system, and applying incident light waves to obtain an output image obtained after an input image passes through the liquid crystal device under the irradiation of the incident light waves; adjusting the wavelength of the incident light wave to a first wavelength value and a second wavelength value to obtain a two-mode image of the input image; the two-mode image comprises an original image and a first-order differential image; the incident polarization state and the emergent polarization state of the incident light wave are both linear polarization states. According to the invention, the problem that the polarization states of incident light and emergent light need to be switched when an original image and a first-order differential image of an input image are displayed by an existing liquid crystal device is solved.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano optical technologies, and particularly to a real-time two-mode image display method based on liquid crystal and a liquid crystal device. Background Art

[0002] For some applications, it is desirable for a liquid crystal variable transmission filter to transmit at least 50% of the unpolarized light incident thereon. A conventional liquid crystal variable transmission filter with high-durability input and output polarizers cannot achieve such a high transmittance because the large light absorption of these polarizers allows the variable transmission filter to transmit only 18% - 20% of the unpolarized light.

[0003] For existing liquid crystal-based image display methods, if it is necessary to output the original image and the high-order differential image, it is necessary to change the polarized light of the input and output to achieve this, and the operation process is relatively cumbersome. For some high-efficiency application scenarios, such as medical imaging, ore screening and other fields, the adaptability is not good.

[0004] Regarding the problem of poor adaptability of existing liquid crystal-based image display methods, no effective solution has been proposed yet. Summary of the Invention

[0005] The present invention provides a real-time two-mode image display method based on liquid crystal and a liquid crystal device to solve the defect of poor adaptability of existing liquid crystal-based image display methods.

[0006] In a first aspect, the present invention provides a real-time two-mode image display method based on liquid crystal, including: Construct a liquid crystal device, and establish a plane rectangular coordinate system according to the working surface of the liquid crystal device; the liquid crystal device has different director vectors at different positions; Place the liquid crystal device on the spectrum plane of a 4f system, and apply an incident light wave to obtain an output image obtained after the input image passes through the liquid crystal device under the irradiation of the incident light wave; Adjust the wavelength of the incident light wave to a first wavelength value and a second wavelength value to obtain a two-mode image of the input image; the two-mode image includes an original image and a first-order differential image; the incident polarization state and the outgoing polarization state of the incident light wave are both linearly polarized states.

[0007] According to the real-time two-mode image display method based on liquid crystal provided by the present invention, establishing a plane rectangular coordinate system according to the working surface of the liquid crystal device includes: Determine the working surface of the liquid crystal device; Set the directions parallel to two sides of the working surface of the liquid crystal device as the x-axis and the y-axis respectively to construct the plane rectangular coordinate system.

[0008] A real-time two-mode image display method based on liquid crystal provided by the present invention, wherein the director direction of the liquid crystal device is the included angle between the major axis of the liquid crystal device and the x-axis.

[0009] A real-time two-mode image display method based on liquid crystal provided by the present invention, adjusting the wavelength of the incident light wave to a first wavelength value and a second wavelength value to obtain a two-mode image of the input image, including: Adjusting the wavelength of the incident light wave to a first wavelength value and a second wavelength value, changing the phase added by the liquid crystal device to the incident light wave, so that the liquid crystal device generates different transfer functions for incident light waves of different wavelengths, and obtaining a two-mode image of the input image.

[0010] A real-time two-mode image display method based on liquid crystal provided by the present invention, the determination of the phase added by the liquid crystal device to the incident light wave includes: Obtaining the refractive index of the liquid crystal major axis and the refractive index of the liquid crystal minor axis of the liquid crystal device, and performing a difference operation; Based on the product of the thickness of the liquid crystal device and the result of the difference operation, determining the phase added by the liquid crystal device to the incident light wave.

[0011] A real-time two-mode image display method based on liquid crystal provided by the present invention, when the wavelength of the incident light wave is the first wavelength value, obtaining the original image of the input image; When the wavelength of the incident light wave is the second wavelength value, obtaining the first-order differential image of the input image.

[0012] A real-time two-mode image display method based on liquid crystal provided by the present invention, when the wavelength of the incident light wave is the first wavelength value, the transfer function modulated by the liquid crystal device to the incident light wave is determined based on the spatial frequency; When the wavelength of the incident light wave is the second wavelength value, the transfer function modulated by the liquid crystal device to the incident light wave is a constant.

[0013] A real-time two-mode image display method based on liquid crystal provided by the present invention, the first wavelength value of the incident light wave is 417 nm, and the second wavelength value of the incident light wave is 477 nm.

[0014] In a second aspect, the present invention further provides a liquid crystal device for implementing the real-time two-mode image display method based on liquid crystal described in the first aspect, including a nematic liquid crystal layer, an optically controlled alignment layer is arranged outside the nematic liquid crystal layer, and a conductive glass is arranged outside the optically controlled alignment layer.

[0015] A liquid crystal device provided by the present invention, wherein the photo-controlled alignment layer includes a first photo-controlled alignment layer and a second photo-controlled alignment layer located on both sides of the nematic liquid crystal layer; the conductive glass includes a first conductive glass layer attached to the first photo-controlled alignment layer and a second conductive glass layer attached to the second photo-controlled alignment layer.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The real-time two-mode image display method based on liquid crystal provided by the present invention utilizes the phase modulation and dispersion characteristics of liquid crystal, selects x-linearly polarized light as the incident light wave, and the polarization state of the outgoing light wave is still the x-linearly polarized state. By adjusting the director at different positions of the liquid crystal device, the original image and the first-order differential image of the input image can be simultaneously displayed when the incident polarization state and the outgoing polarization state of the incident light wave at different wavelengths are the same, avoiding the problem that the prior liquid crystal device needs to switch the polarization states of the incident light and the outgoing light for displaying the original image and the first-order differential image of the input image, and has important application prospects in the fields of medical imaging, ore screening, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a flowchart of the real-time two-mode image display method based on liquid crystal provided by the present invention; Figure 2 It is a schematic diagram of the director distribution of the liquid crystal device in the embodiment of the present invention; Figure 3 It is a schematic diagram of the image displayed on the detector when the wavelength of the incident light wave is 417 nm in the embodiment of the present invention; Figure 4 It is a schematic diagram of the image displayed on the detector when the wavelength of the incident light wave is 477 nm in the embodiment of the present invention; Figure 5 It is a schematic diagram of the structure of the liquid crystal device provided by the present invention; Figure 6 It is a schematic diagram of the optical path where the liquid crystal device is located in the embodiment of the present invention.

[0019] REFERENCE SIGNS: 110: First conductive glass layer; 120: First photo-controlled alignment layer; 130: Nematic liquid crystal layer; 140: Second photo-controlled alignment layer; 150: Second conductive glass layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] The present invention provides a real-time two-mode image display method based on liquid crystal. Figure 1 It is a flowchart of the real-time two-mode image display method based on liquid crystal provided by the present invention. As Figure 1 shown, the method includes the following steps: Step S101: Construct a liquid crystal device and establish a rectangular coordinate system on the working surface of the liquid crystal device; the liquid crystal device has different director vectors at different positions. Step S102: Place the liquid crystal device on the spectrum plane of the 4f system and apply an incident light wave to obtain an output image obtained after the input image passes through the liquid crystal device under the irradiation of the incident light wave. Step S103: Adjust the wavelength of the incident light wave to a first wavelength value and a second wavelength value to obtain a two-mode image of the input image; the two-mode image includes an original image and a first-order differential image; the incident polarization state and the outgoing polarization state of the incident light wave are both linear polarization states.

[0022] In this method, first, a liquid crystal device for realizing real-time two-mode image display is constructed. The liquid crystal device has a certain thickness and different director vectors at different positions. And, a rectangular coordinate system, i.e., the xoy coordinate system, is established on the working surface of the liquid crystal device. Then, through theoretical calculation and simulation, the liquid crystal device is placed on the spectrum plane of the 4f system, where f is the focal length of the lens of the 4f system, to obtain an output image obtained after the input image passes through the liquid crystal device under the irradiation of the incident light wave. Finally, the wavelength of the incident light wave is adjusted to a first wavelength value λ1 and a second wavelength value λ2 to obtain the original image and the first-order differential image of the input image. In the above process, by utilizing the phase modulation and dispersion characteristics of the liquid crystal, an x linearly polarized light is selected as the incident light wave, and the polarization state of the outgoing light wave is still the x linearly polarized light. By adjusting the director vectors at different positions of the liquid crystal device, the original image and the first-order differential image of the input image can be simultaneously displayed when the incident polarization state and the outgoing polarization state of the incident light wave at different wavelengths are the same, avoiding the problem that the existing liquid crystal device needs to switch the polarization states of the incident light and the outgoing light for the display of the original image and the first-order differential image of the input image, and having an important application prospect in the fields of medical imaging, ore screening, etc.

[0023] In some of these embodiments, step S101 of establishing a rectangular coordinate system based on the working surface of the liquid crystal device includes: determining the working surface of the liquid crystal device; respectively setting the directions of two sides parallel to the working surface of the liquid crystal device as the x-axis and the y-axis to construct a rectangular coordinate system. Based on this, the direction of the director of the liquid crystal device is the angle between the major axis of the liquid crystal device and the x-axis, as Figure 2 shown, Figure 2 which is a schematic diagram of the director distribution of the liquid crystal device in an embodiment of the present invention.

[0024] Exemplarily, for the construction of the liquid crystal device, it includes the following steps: 1. Determine the material of the liquid crystal device and the thickness H of the liquid crystal device.

[0025] 2. Calculate the phase delay amount φ added by the liquid crystal device to the incident light of different wavelengths according to the long and short axis refractive indices ne and no of the liquid crystal device at different wavelengths and the thickness H of the liquid crystal device, and select the incident light wavelengths with phase delay amounts of k×2π and k×2π+π respectively for use as the working wavelengths for outputting the original image and the first-order differential image of the target image.

[0026] 3. Arrange the directors of the liquid crystal device, and arrange the directors according to the normalized coordinates in the x-direction at different positions of the liquid crystal device.

[0027] In some of these embodiments, step S103 of adjusting the wavelength of the incident light wave to the first wavelength value and the second wavelength value to obtain the two-mode image of the input image includes: adjusting the wavelength of the incident light wave to the first wavelength value and the second wavelength value, changing the phase added by the liquid crystal device to the incident light wave, so that the liquid crystal device generates different transfer functions for incident light waves of different wavelengths, and obtaining the two-mode image of the input image.

[0028] Based on this embodiment, the determination of the phase added by the liquid crystal device to the incident light wave includes: obtaining the long axis refractive index and the short axis refractive index of the liquid crystal of the liquid crystal device and performing a difference operation; based on the product of the thickness of the liquid crystal device and the result of the difference operation, determining the phase added by the liquid crystal device to the incident light wave.

[0029] When the wavelength of the incident light wave is the first wavelength value, the transfer function of the modulation of the incident light wave by the liquid crystal device is determined based on the spatial frequency, and the original image of the input image is obtained; when the wavelength of the incident light wave is the second wavelength value, the transfer function of the modulation of the incident light wave by the liquid crystal device is a constant, and the first-order differential image of the input image is obtained.

[0030] Preferably, the first wavelength value of the incident light wave is 417 nm, and the second wavelength value of the incident light wave is 477 nm.

[0031] Exemplarily, the thickness of the liquid crystal device is:

[0032] Among them, H represents the thickness of the liquid crystal device. The director directions at different positions of the liquid crystal are as follows:

[0033] Among them, θ is the director direction at different positions of the liquid crystal device, x is the abscissa at different positions of the liquid crystal device, and D is the side length of the liquid crystal device. For a liquid crystal device with a thickness of H, the additional phase imposed on the incident light wave is:

[0034] Among them, ne is the refractive index of the long axis of the liquid crystal, and no is the refractive index of the short axis of the liquid crystal. For different incident wavelengths, ne and no exhibit different values.

[0035] For the incident wavelength λ1, the additional phase modulation amount of the liquid crystal device is 5π, and for the incident wavelength λ2, the additional phase modulation amount of the liquid crystal device is 4π. When the incident light wave with a wavelength of λ1 is incident, the transfer function of the liquid crystal device for modulating the incident light wave is:

[0036] Among them, is the transfer function, is a constant, is the spatial frequency, where w = x / D . When the incident light wave with a wavelength of λ2 is incident, the transfer function of the liquid crystal device for modulating the incident light wave is:

[0037] Among them, is the transfer function, is a constant. For the incident light waves with wavelength values of λ1 and λ2, the incident and outgoing polarization states of both are linearly polarized states along the x direction.

[0038] For the liquid crystal device, the following is further explained: The liquid crystal device has different angular distributions at different positions, and the liquid crystal can be equivalent to a wave plate. The phase modulation effects at different positions of the liquid crystal can be equivalent to wave plates with different fast axis directions. Therefore, when x-linearly polarized light is incident and x-linearly polarized light is emitted, the complex amplitude modulation amount imposed on the light wave at a certain position of the liquid crystal device is:

[0039] Among them, represents the complex amplitude modulation amount, θ is the director direction at different positions of the liquid crystal device, is the additional phase imposed on the input light wave at different positions of the liquid crystal device.

[0040] More specifically, when the wavelength of the incident light wave is 417 nm, the long-axis refractive index ne of the liquid crystal device for the incident light wave is 1.74, the short-axis refractive index no is 1.566, and the additional phase is φ = 5π; when the wavelength of the incident light wave is 477 nm, the long-axis refractive index ne of the liquid crystal device for the incident light wave is 1.7115, the short-axis refractive index no is 1.5521, and the additional phase is φ = 4π.

[0041] At this time, the additional complex amplitude of the liquid crystal device for the incident light wave with a wavelength of 417 nm is:

[0042] Among them, represents the complex amplitude modulation amount, i is the imaginary unit, and θ is the direction of the director at different positions of the liquid crystal device. The additional complex amplitude for the incident light wave with a wavelength of 477 nm is:

[0043] Among them, represents the complex amplitude modulation amount. Since the transfer function form of the first-order differentiator is:

[0044] Among them, is the transfer function, i is the imaginary unit, and w is the frequency; in order to match the additional complex amplitude of the liquid crystal device for the outgoing light wave under the illumination of the incident light wave with a wavelength of 417 nm with the transfer function form of the first-order differentiator, let:

[0045] Among them, θ is the direction of the director at different positions of the liquid crystal device, x is the abscissa at different positions of the liquid crystal device, and D is the side length of the liquid crystal device. That is, the additional complex amplitude of the liquid crystal device for the incident light wave with a wavelength of 417 nm is:

[0046] At this time, the transfer function can be made to match the transfer function form of the first-order differentiator. As Figure 3 shown, Figure 3 is a schematic diagram of the image displayed on the detector when the wavelength of the incident light wave is 417 nm in the embodiment of the present invention. When the wavelength of the incident light wave is 417 nm, the additional complex amplitude of the liquid crystal for the outgoing light is H = -ix / D , and at this time, the liquid crystal device will act on the spectrum of the input image on the spectrum plane, and finally, the first-order differential image of the target image will be received on the detector plane.

[0047] When the wavelength of the incident light is 477 nm, as Figure 4 shown,Figure 4 It is a schematic diagram of the image displayed on the detector when the wavelength of the incident light wave in the embodiment of the present invention is 477 nm. The complex amplitude added by the liquid crystal device to the outgoing light is a constant 1, that is, it does not modulate the spectrum of the target image. Therefore, the original image of the input image will be received on the detector. By changing the wavelength of the incident light, the original image and the first-order differential image of the input image can be observed separately on the detector.

[0048] In summary, this method selects x-ray polarized light as the incident light wave, and utilizes the property that the form of the complex amplitude added by the outgoing x-ray polarized light is related to the wavelength. When the thickness of the liquid crystal device and the material birefringence are determined, by adjusting the wavelength of the incident light wave, the complex amplitude added by the outgoing x-ray polarized light can be changed, which can be respectively matched with the transfer functions of the first-order differential image output and the original image output, thus realizing the real-time display of the original image and the first-order differential image of the target image, and avoiding the problem that the existing scheme of switching the polarization states of the incident light and the outgoing light cannot display the original image and the first-order differential image of the target image at the same time. In addition, the liquid crystal device in this method has a compact structure, small volume and light weight, and has great industrialization prospects in the fields of medical imaging, ore screening, etc.

[0049] The present invention also provides a liquid crystal device for implementing the above-mentioned real-time two-mode image display method based on liquid crystals. Figure 5 It is a schematic structural diagram of the liquid crystal device provided by the present invention, as Figure 5 shown. The liquid crystal device includes a nematic liquid crystal layer 130. An optical control alignment layer is arranged outside the nematic liquid crystal layer 130, and a conductive glass is arranged outside the optical control alignment layer. Preferably, in order to facilitate the assembly of the liquid crystal device, the liquid crystal device has a square structure. The angle between the director of the liquid crystal device at different positions and the x-axis is θ.

[0050] Specifically, the optical control alignment layer includes a first optical control alignment layer 120 and a second optical control alignment layer 140 located on both sides of the nematic liquid crystal layer 130; the conductive glass includes a first conductive glass layer 110 attached to the first optical control alignment layer 120 and a second conductive glass layer 150 attached to the second optical control alignment layer 140.

[0051] When this liquid crystal device is used in the experimental optical path, as Figure 6 shown. Figure 6It is a schematic diagram of the optical path where the liquid crystal device is located in the embodiment of the present invention. This optical path mainly consists of a laser, two convex lenses with a focal length of f each, and the liquid crystal device designed by the present invention. The object is placed at the front focal plane of lens 1, the liquid crystal is placed at the rear focal plane of lens 1, the rear focal plane of lens 1 coincides with the front focal plane of lens 2, and the detector is placed at the rear focal plane of lens 2. By changing the output light wavelength of the laser, the original image or the first-order differential image of the target image can be received on the detector.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A real-time dual-mode image display method based on liquid crystal, characterized in that, Comprising: Constructing a liquid crystal device and establishing a rectangular coordinate system based on the working surface of the liquid crystal device; the liquid crystal device has different director vectors at different positions; Placing the liquid crystal device on the spectrum plane of a 4f system and applying an incident light wave to obtain an output image obtained after the input image passes through the liquid crystal device under the irradiation of the incident light wave; Adjusting the wavelength of the incident light wave to a first wavelength value and a second wavelength value to obtain a two-mode image of the input image; the two-mode image includes an original image and a first-order differential image; the incident polarization state and the outgoing polarization state of the incident light wave are both linear polarization states.

2. The real-time dual-mode image display method based on liquid crystal according to claim 1, wherein Establishing a rectangular coordinate system based on the working surface of the liquid crystal device, including: Determining the working surface of the liquid crystal device; Taking the directions of two sides parallel to the working surface of the liquid crystal device as the x-axis and the y-axis respectively to construct the rectangular coordinate system.

3. The real-time dual-mode image display method based on liquid crystal according to claim 2, wherein The direction of the director vector of the liquid crystal device is the angle between the long axis of the liquid crystal device and the x-axis.

4. The real-time dual-mode image display method based on liquid crystal according to claim 1, wherein Adjusting the wavelength of the incident light wave to a first wavelength value and a second wavelength value to obtain a two-mode image of the input image, including: Adjusting the wavelength of the incident light wave to a first wavelength value and a second wavelength value, changing the phase added by the liquid crystal device to the incident light wave, so that the liquid crystal device has different transfer functions for incident light waves of different wavelengths, and obtaining a two-mode image of the input image.

5. The real-time dual-mode image display method based on liquid crystal according to claim 4, wherein Determining the phase added by the liquid crystal device to the incident light wave, including: Obtaining the refractive index of the liquid crystal long axis and the refractive index of the liquid crystal short axis of the liquid crystal device and performing a difference operation; Based on the product of the thickness of the liquid crystal device and the result of the difference operation, determining the phase added by the liquid crystal device to the incident light wave.

6. The real-time dual-mode image display method based on liquid crystal according to claim 4, characterized in that When the wavelength of the incident light wave is the first wavelength value, obtaining the original image of the input image; When the wavelength of the incident light wave is the second wavelength value, obtaining the first-order differential image of the input image.

7. The real-time two-mode image display method based on liquid crystal according to claim 6, wherein When the wavelength of the incident light wave is the first wavelength value, the transfer function modulated by the liquid crystal device for the incident light wave is determined based on the spatial frequency; When the wavelength of the incident light wave is the second wavelength value, the transfer function modulated by the liquid crystal device for the incident light wave is a constant.

8. The real-time two-mode image display method based on liquid crystal according to claim 1, characterized in that The first wavelength value of the incident light wave is 417 nm, and the second wavelength value of the incident light wave is 477 nm.

9. A liquid crystal device for implementing the liquid crystal-based real-time two-mode image display method according to any one of claims 1-8, characterized in that, Including a nematic liquid crystal layer (130), an optically controlled alignment layer is provided outside the nematic liquid crystal layer (130), and a conductive glass is provided outside the optically controlled alignment layer.

10. The liquid crystal device according to claim 9, wherein the optically controlled alignment layer includes a first optically controlled alignment layer (120) and a second optically controlled alignment layer (140) located on both sides of the nematic liquid crystal layer (130); the conductive glass includes a first conductive glass layer (110) attached to the first optically controlled alignment layer (120) and a second conductive glass layer (150) attached to the second optically controlled alignment layer (140).

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