Optical system based on liquid crystal dual-mode imaging lens and imaging method

Abstract

The invention is mainly used in the technical field of optical microscopy. The invention discloses an optical system and an imaging method based on a liquid crystal dual-mode imaging lens, and the optical system comprises an incident light path module which is used for transmitting laser to a target sample, and the laser penetrates through the target sample; the liquid crystal dual-mode imaging lens module is provided with at least two independent and controllable electrode areas and is used for receiving light waves which penetrate through a target sample and carry sample information and then performing first-type phase modulation on first parts of the light waves at the same time point through the corresponding electrode areas so as to form a bright field imaging light path; carrying out second-type phase modulation on the second part of the light wave to form an edge enhancement imaging light path; and the imaging detection module is used for receiving the first light wave transmitted through the bright field imaging light path and the second light wave transmitted through the edge enhancement imaging light path so as to obtain bright field image information and edge enhancement image information. According to the invention, bright field imaging and edge enhancement imaging information can be synchronously acquired.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical microscopy, in particular to an optical system and imaging method based on a liquid crystal dual-mode imaging lens. BACKGROUND

[0002] Microscopic imaging technology is a core means for observing the morphology and structure of micro samples, and is widely used in the fields of biomedical science and material analysis. In traditional microscopic imaging methods, bright-field imaging uses a condenser for full-aperture illumination, and an objective lens receives the direct light and diffraction light transmitted or reflected by the sample, forming an image with a bright background and contrast dependent on the light absorption or amplitude difference of the sample. This method is simple in structure and has high light efficiency, but it is difficult to distinguish the fine morphology of the sample due to insufficient contrast of the edge and internal details of the transparent and weakly absorbing sample.

[0003] To improve the contrast of transparent samples, edge enhancement techniques have emerged. Phase-contrast imaging sets a ring-shaped diaphragm at the focal plane of the condenser and introduces a phase plate at the back focal plane of the objective lens, which converts the phase difference of the sample into intensity difference by modulating the phase of the direct light, achieving edge and structure enhancement. DIC technology uses polarized light and a Nomarski prism to generate two micro-sheared light beams, which are modulated by the phase gradient of the sample and then interfere to generate a relief-like edge image with a three-dimensional effect. Dark-field imaging blocks the direct light from entering the objective lens by a central light-blocking plate, and only receives the scattered light of the sample, highlighting the edge profile in a dark background.

[0004] However, the optical implementation paths of the above-mentioned techniques are essentially exclusive, resulting in the inability to implement them simultaneously in the same optical device. Bright-field imaging requires the full opening of the optical path to maximize the collection of direct light, while phase-contrast and dark-field imaging must insert specific diaphragms, light-blocking plates, or phase plates at the conjugate planes of the condenser or objective lens, physically blocking or modulating the direct light component required for bright-field imaging. DIC relies on polarization splitting and prism shearing mechanisms, and its optical elements also interfere with the integrity and polarization neutrality of the bright-field optical path. In addition, each module occupies the same physical space in the optical path, and the system must switch or replace the condenser / objective lens components to convert the imaging mode, which cannot achieve simultaneous acquisition in the same field of view at the same time. Therefore, traditional microscopic imaging techniques are limited by the contradiction between optical structure exclusivity and working mechanism, and cannot simultaneously obtain bright-field intensity information and edge-enhanced contrast information in the same optical system, restricting the ability to simultaneously characterize samples in multiple dimensions, and there is an urgent need for a new optical architecture that can accommodate both. SUMMARY

[0005] The present application provides an optical system and imaging method based on a liquid crystal dual-mode imaging lens, which can simultaneously acquire bright-field imaging and edge-enhanced imaging information.

[0006] The present application provides an optical system based on a liquid crystal dual-mode imaging lens, which comprises: An incident light path module configured to emit laser light to a target sample, wherein the laser light transmits through the target sample; A liquid crystal dual-mode imaging lens module having at least two independently controllable electrode regions, configured to, after receiving light waves carrying sample information that transmit through the target sample, perform first type phase modulation on a first portion of the light waves through a corresponding electrode region to form a bright field imaging light path and perform second type phase modulation on a second portion of the light waves to form an edge-enhanced imaging light path at the same time point; An imaging detection module configured to receive the first light waves transmitted through the bright field imaging light path and the second light waves transmitted through the edge-enhanced imaging light path to obtain bright field image information and edge-enhanced image information.

[0007] Optionally, the liquid crystal dual-mode imaging lens module is further configured to: perform grating beam splitting phase modulation on the laser light to output the first light waves and the second light waves and transmit them to corresponding regions in the imaging detection module after being spatially separated.

[0008] Optionally, the specific manner of performing second type phase modulation on the second portion of the light waves includes: modulating the second light waves through annular high-pass filtering in a spatial frequency domain to suppress low-frequency background light components of the second light waves and enhance high-frequency light components containing edge information of the target sample to obtain an edge contrast-enhanced image projected by the second light waves.

[0009] Optionally, the liquid crystal dual-mode imaging lens module is further configured to: maintain preset diffraction efficiency and transmittance in a wide spectral range by inputting a corresponding half-wave voltage of the laser light.

[0010] Optionally, the incident light path module includes, in sequence along an optical axis, a light source unit, a filtering and collimating unit, a polarization control unit, and a beam scaling unit. The light source unit is configured to provide the laser light. The filtering and collimating unit is located on an exit light path of the light source unit and is configured to filter stray light and convert the laser light into parallel light. The polarization control unit is located on an exit light path of the filtering and collimating unit and is configured to adjust the parallel light into circularly polarized light. The beam scaling unit is located on an exit light path of the polarization control unit and is configured to perform beam diameter scaling processing on the circularly polarized light to make a spot size of the circularly polarized light match an effective modulation region of the liquid crystal dual-mode imaging lens module.

[0011] Optionally, the beam scaling unit is further configured to: When the target sample is a biological cell sample, a sample image of the target sample is magnified according to a first magnification to match an effective modulation area of the liquid crystal dual-mode imaging lens module; When the target sample is a resolution test target, a sample image of the target sample is reduced according to a second magnification to match a minimum resolvable line width of the liquid crystal dual-mode imaging lens module.

[0012] Optionally, the imaging detection module comprises a displacement table and a camera device; The displacement table is configured to adjust a distance between a detection plane of the imaging detection module and the liquid crystal dual-mode imaging lens module along an optical axis direction, and to adjust the detection plane of the camera device to a corresponding imaging focal plane according to a wavelength of the laser. The camera device is arranged on the displacement table and is configured to acquire the first light wave and the second light wave and output corresponding images of the first light wave and the second light wave, respectively.

[0013] The application further provides an imaging method based on a liquid crystal dual-mode imaging lens, which is implemented by using any one of the optical systems based on the liquid crystal dual-mode imaging lens. The incident light path module is configured to emit a laser and irradiate the laser to a target sample. After the light wave carrying sample information and passing through the target sample is incident on the liquid crystal dual-mode imaging lens module, a half-wave voltage corresponding to the light wave is input to an electrode area of the liquid crystal dual-mode imaging lens module. The half-wave voltage is controlled to enable the liquid crystal dual-mode imaging lens module to perform first-type phase modulation on a first part of the light wave to form a bright-field imaging light path and perform second-type phase modulation on a second part of the light wave to form an edge-enhanced imaging light path at the same time point. The imaging detection module is configured to receive the first light wave output by the bright-field imaging light path and the second light wave output by the edge-enhanced imaging light path, and generate corresponding bright-field images and edge-enhanced images, respectively.

[0014] Optionally, the imaging method further comprises: In response to an instruction to switch an imaging wavelength, the half-wave voltage input to the liquid crystal dual-mode imaging lens module and a diffraction distance between a camera device and a lens in the imaging detection module are adjusted to generate bright-field images and edge-enhanced images corresponding to the target wavelength.

[0015] Optionally, the imaging method further comprises a step of calibrating a resolution capability of the optical system by using a resolution test target. An Airy disk diameter is obtained by measuring the first light wave output by the bright-field imaging light path. obtaining the vortex light diameter by measuring the second light wave output by the edge-enhanced imaging light path; comparing the Airy spot diameter and the vortex light diameter with corresponding theoretical simulation values respectively, and determining a score value of the optical system according to a comparison result.

[0016] The present application has at least the following beneficial effects: The present technical solution realizes the effect of synchronously collecting bright field imaging and edge-enhanced imaging information through a unique optical system design. The core lies in a liquid crystal double-mode imaging lens module, which has at least two independently controllable electrode regions. When the light wave carrying sample information through the target sample enters the module, the two electrode regions can respectively perform different types of phase modulation on different parts of the light wave. Specifically, one electrode region performs a first type of phase modulation on a first part of the light wave to form a bright field imaging light path; the other electrode region performs a second type of phase modulation on a second part of the light wave to form an edge-enhanced imaging light path. Since the formation of the two types of imaging light paths is based on the light wave at the same time point and is independently controlled by different electrode regions of the same lens module, bright field imaging and edge-enhanced imaging can be realized. The imaging detection module receives the light waves transmitted by the two types of light paths to obtain corresponding image information, thereby achieving the purpose of synchronously collecting two types of imaging information and providing more comprehensive sample information for subsequent image processing and analysis. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and are used to explain the technical solutions of the present application together with embodiments of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0018] Figure 1 is a step flow chart of an optical system based on a liquid crystal double-mode imaging lens; Figure 2 is an imaging principle diagram of a liquid crystal double-mode imaging lens in an optical system based on the liquid crystal double-mode imaging lens; Figure 3 is a voltage-phase delay curve diagram measured for the liquid crystal double-mode imaging lens in the optical system; Figure 4 is a voltage-transmittance curve diagram measured for the liquid crystal double-mode imaging lens in the optical system; Figure 5 is a theoretical simulation result schematic diagram of a point spread function of the liquid crystal double-mode imaging lens under 632.8 nm incident light; Figure 6 is an experimental measurement result schematic diagram of a point spread function of the liquid crystal double-mode imaging lens under 632.8 nm incident light; Figure 7is a schematic diagram of the theoretical and experimental comparison results of the normalized intensity distribution of the center section of the bright field mode in the optical system. Figure 8 is a schematic diagram of the theoretical and experimental comparison results of the normalized intensity distribution of the center section of the spiral phase contrast mode in the optical system. Figure 9 is a schematic diagram of the microscopic imaging results of wheat epithelial cells by an optical system based on a liquid crystal dual-mode imaging lens. Figure 10 is a step flowchart of an imaging method based on a liquid crystal dual-mode imaging lens. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0020] It should be noted that the existing related technology has many key shortcomings: single-mode imaging cannot simultaneously achieve "real-time observation" and "edge information acquisition", bright field imaging, although simple to operate and capable of real-time observation, cannot distinguish the phase structure of a transparent sample, traditional spiral phase contrast imaging, although capable of edge enhancement, relies on a large 4f system and spatial separation of elements such as vortex phase plates, increasing the volume of the device and the difficulty of calibration, and is difficult to integrate into a small microscope platform; the traditional multi-modal scheme, although trying to combine the two modalities, requires independent hardware for bright field imaging and edge enhancement imaging, further increasing the complexity of the system and the use threshold. At the same time, the traditional multi-modal scheme relies on "mode switching" to achieve different imaging functions, and cannot simultaneously acquire bright field and edge enhancement data. This "non-synchronous" feature can easily lead to errors in recording intercellular correlation information in live cell imaging, making it difficult to accurately reflect dynamic biological processes. In addition, traditional optical elements are essentially single-function designs and cannot simultaneously achieve the functions of bright field imaging and edge enhancement in the same device. Some schemes have limited wavelength adaptability, making it difficult to maintain stable imaging effects and diffraction efficiency in a wide spectral range. At the same time, traditional schemes also have the problems of high integration difficulty of large size, lack of low-cost mass production path, resulting in high equipment cost, and difficulty in reducing the use threshold of biomedical microscopic imaging.

[0021] Please refer to Figure 1 , Figure 1 is a step flowchart of an optical system based on a liquid crystal dual-mode imaging lens.

[0022] The present embodiment provides an optical system based on a liquid crystal dual-mode imaging lens, which comprises: An incident light path module 100 for emitting laser light to a target sample, the laser light penetrating the target sample.

[0023] The liquid crystal dual-mode imaging lens module 200 has at least two independently controllable electrode regions, which are used to receive light waves carrying sample information transmitted through a target sample, and at the same time point, a first part of the light waves is subjected to a first type of phase modulation through the corresponding electrode region to form a bright field imaging light path, and a second part of the light waves is subjected to a second type of phase modulation to form an edge enhancement imaging light path.

[0024] The imaging detection module 300 is used to receive the first light waves transmitted through the bright field imaging light path and the second light waves transmitted through the edge enhancement imaging light path to obtain bright field image information and edge enhancement image information.

[0025] In the embodiment, the optical system based on the liquid crystal dual-mode imaging lens is composed of an incident light path module, a core liquid crystal dual-mode imaging lens, and an imaging detection module arranged in sequence along an optical axis, and the dual-mode synchronous imaging can be realized without a traditional 4f system.

[0026] The imaging detection module does not need an additional filtering component. Since the liquid crystal dual-mode imaging lens has realized spatial separation of dual-mode light spots, a camera can directly collect, avoids the redundant structure of Fourier filtering in the traditional 4f system, simplifies the optical path, and reduces the alignment error.

[0027] Compared with the prior art scheme, for example, the traditional spiral phase contrast imaging scheme relying on the 4f system, the multi-modal attempt scheme based on polarization state switching or electrically adjustable devices, the present scheme has significant advantages in hardware architecture, imaging synchronism, wide spectral adaptability, size and cost control, and imaging resolution and biological adaptability.

[0028] In terms of hardware architecture, the existing multi-modal scheme needs to provide an independent lens device for bright field imaging and additionally build a 4f system including a vortex phase plate and a beam splitter for edge enhancement imaging. The hardware is scattered and bulky, the calibration process is complex, and it is difficult to adapt to a small microscope platform. The present application integrates the functions of “lens phase, vortex phase, and offset grating phase” through a single electrically controlled liquid crystal device, and can simultaneously realize two imaging modes without additional auxiliary elements, greatly simplifies the system structure, reduces the integration difficulty, and is more easily combined with a small-sized microscopic device.

[0029] In some embodiments, the incident light path module can adapt to different sizes of samples: for biological samples (such as wheat epidermal cells), the sample image is enlarged to 500 μm through a 20x microscope eyepiece to ensure that the incident light spot covers the effective area of the device; for a standard resolution target (such as a USAF 1951 resolution target), the line pair size is reduced to 39.375 μm (the smallest resolvable line width) through a 4x beam reduction system (L2=200 mm, L3=50 mm), meeting the high resolution test requirements.

[0030] It can be understood that the embodiment realizes the effect of synchronously collecting bright field imaging and edge enhancement imaging information through a unique optical system design. The core is a liquid crystal double-mode imaging lens module. The module has at least two independently controllable electrode regions. When the light waves carrying sample information passing through the target sample enter the module, the two electrode regions can respectively perform different types of phase modulation on different parts of the light waves. Specifically, one electrode region performs a first type of phase modulation on a first part of the light waves to form a bright field imaging light path; another electrode region performs a second type of phase modulation on a second part of the light waves to form an edge enhancement imaging light path. Since the formation of the two imaging light paths is based on the light waves at the same time point and is independently controlled by different electrode regions of the same lens module, bright field imaging and edge enhancement imaging can be realized. The imaging detection module receives the light waves transmitted by the two light paths and obtains the corresponding image information, thereby achieving the purpose of synchronously collecting the two types of imaging information and providing more comprehensive sample information for subsequent image processing and analysis.

[0031] In some embodiments, the incident light path module includes, in sequence along the optical axis, a light source unit, a filtering collimation unit, a polarization control unit, and a light beam scaling unit.

[0032] The light source unit is configured to provide laser light.

[0033] The filtering collimation unit is located on the exit light path of the light source unit and is configured to filter stray light and convert the laser light into parallel light.

[0034] The polarization control unit is located on the exit light path of the filtering collimation unit and is configured to adjust the parallel light into circularly polarized light.

[0035] The light beam scaling unit is located on the exit light path of the polarization control unit and is configured to perform light beam diameter scaling processing on the circularly polarized light, so that the spot size of the circularly polarized light matches the effective modulation area of the liquid crystal double-mode imaging lens module.

[0036] In some embodiments, the light beam scaling unit is further configured to: When the target sample is a biological cell sample, the sample image of the target sample is magnified to match the effective modulation area of the liquid crystal double-mode imaging lens module according to the first magnification; when the target sample is a resolution test target, the sample image of the target sample is reduced to match the minimum resolvable line width of the liquid crystal double-mode imaging lens module according to the second magnification.

[0037] In some embodiments, the light source unit uses a wide-spectrum light source (covering 450 nm-632.8 nm, such as a red laser 632.8 nm, a green LED 520 nm, and a blue LED 450 nm) to provide stable monochromatic light.

[0038] In some embodiments, the filtering collimation unit is composed of a 10x eyepiece, a 50 μm pinhole diaphragm (IR), and a collimating lens with a focal length of 500 mm, which filters stray light and converts divergent light into parallel light.

[0039] In some embodiments, the polarization regulation unit is composed of a quarter-wave plate, which converts linearly polarized light into left-handed circularly polarized light, matching the circularly polarized incident requirement of the liquid crystal bimodal imaging lens.

[0040] In some embodiments, the beam scaling unit is composed of a 4f scaling system with a pair of lenses (e.g., L2 = 250 mm and L3 = 50 mm), which scales the light beam by 5x to 400 μm according to the sample size (2 mm original sample), ensuring that the incident spot is adapted to the effective area of the liquid crystal bimodal imaging lens (12.2472 mm x 12.2472 mm).

[0041] It can be understood that through the synergistic effect of the light source unit, the filtering collimation unit, the polarization regulation unit, and the beam scaling unit, high-quality transmission and precise regulation of the laser are achieved. The filtering collimation unit filters stray light and converts it into parallel light, the polarization regulation unit adjusts the light to circularly polarized light, and the beam scaling unit adjusts the beam diameter according to the target sample type (such as a biological cell sample or a resolution test target), so that the spot size is precisely matched with the effective modulation area of the liquid crystal bimodal imaging lens module. This design not only improves the clarity and contrast of the imaging, but also enhances the versatility and flexibility of the system, making it adaptable to different types of sample imaging needs, further optimizing the simultaneous acquisition effect of bright field imaging and edge enhancement imaging.

[0042] In some embodiments, the first type of phase modulation on the first part of the light wave refers to lens focusing phase modulation, specifically, a quadratic phase is used to realize beam focusing, and a 0th-order Gaussian light carrying sample amplitude information is output (bright field imaging).

[0043] In some embodiments, the second type of phase modulation on the second part of the light wave refers to vortex phase modulation, specifically, a topological charge azimuthal phase is used to introduce orbital angular momentum, and a -1st-order vortex light is output (spiral phase contrast imaging, edge enhancement function).

[0044] In some embodiments, the liquid crystal bimodal imaging lens module is further used for: performing grating beam splitting phase modulation on the laser to output the first light wave and the second light wave and transmit them to corresponding areas in the imaging detection module after being spatially separated.

[0045] Specifically, the grating beam splitting phase uses a sinusoidal grating phase to realize spatial separation of Gaussian light and vortex light in the y direction, avoiding imaging overlap.

[0046] In some embodiments, the specific way of performing the second type of phase modulation on the second part of the light wave comprises: In the spatial frequency domain, the second light wave is modulated by annular high-pass filtering to suppress the low-frequency background light component of the second light wave and enhance the high-frequency light component containing the edge information of the target sample, so as to obtain an edge contrast-enhanced image projected by the second light wave.

[0047] Please refer to Figure 2 , Figure 2 is an imaging principle diagram of a liquid crystal dual-mode imaging lens in an optical system based on the liquid crystal dual-mode imaging lens.

[0048] It should be noted that the liquid crystal dual-mode imaging lens 102 of the liquid crystal dual-mode imaging lens module integrates three different functional phase components in a single device, thereby realizing a compact and multifunctional liquid crystal optical element. The secondary phase modulation of the lens can be realized in the following way: the Gaussian mode carries the phase information of the object. The vortex mode is the orbital angular momentum with a topological charge In the optical imaging system involving Fourier transform, the essence is to modulate the spatial frequency domain of the object light field 101 by a spiral phase factor (θ is the azimuth angle). When the vortex light carrying orbital angular momentum is subjected to Fourier transform, its spectral distribution satisfies (J1 is the first Bessel function), and annular high-pass filtering characteristics are formed in the frequency domain. By suppressing the low-frequency background component (k0 ) and strengthening the high-frequency passband region (k0 , f is the focal length of the lens) carrying the edge information, after inverse Fourier transform reconstruction, the contrast of the image gradient feature can be significantly improved, and finally the edge enhancement effect is also presented on the image plane 103, highlighting the detailed information of the object edge.

[0049] In some embodiments, the liquid crystal dual-mode imaging lens module is also used for: By inputting the half-wave voltage corresponding to the laser, the preset diffraction efficiency and transmittance are maintained in a wide spectral range.

[0050] In some embodiments, the liquid crystal dual-mode imaging lens module adjusts the wide spectral adaptability by voltage control: for 450 nm, 520 nm, and 632.8 nm wavelengths, 5.35 V, 4.56 V, and 3.87 V half-wave voltages are applied respectively, to ensure that high diffraction efficiency (average 80.23%) and high transmittance (average >99.5%) are maintained under different wavelengths.

[0051] It can be understood that by grating beam splitting phase modulation, the liquid crystal double-mode imaging lens module can separate the first light wave and the second light wave in space and transmit them to the corresponding areas of the imaging detection module, avoiding mutual interference between the two light waves, and improving the clarity and accuracy of imaging. At the same time, the second light wave is phase modulated by annular high-pass filtering, effectively suppressing the low-frequency background light component, significantly enhancing the edge information and high-frequency light component of the target sample, thereby obtaining an edge-enhanced image with higher contrast, and improving the detail performance of the image. In addition, by inputting the corresponding half-wave voltage of the laser, the preset diffraction efficiency and transmittance are maintained in a wide spectral range, enhancing the stability and adaptability of the system. These improvements enable the optical system to obtain higher quality, clearer and higher contrast images when simultaneously collecting bright field imaging and edge-enhanced imaging information, providing more reliable data support for subsequent image analysis and application.

[0052] In some embodiments, the imaging detection module includes a displacement stage and a camera device.

[0053] The displacement stage is used to adjust the distance between the detection plane of the imaging detection module and the liquid crystal double-mode imaging lens module along the optical axis direction, and to adjust the detection plane of the camera device to the corresponding imaging focal plane according to the wavelength of the laser.

[0054] The camera device is disposed on the displacement stage and is used to acquire the first light wave and the second light wave, and output the corresponding images of the first light wave and the second light wave, respectively.

[0055] In some embodiments, on the displacement stage, the distance between the camera and the liquid crystal double-mode imaging lens (diffraction distance) is adjusted along the optical axis direction, and the focal plane is matched according to the wavelength (632.8 nm corresponds to 0.10 m, 520 nm corresponds to 0.116 m, and 450 nm corresponds to 0.135 m).

[0056] In some embodiments, the camera device simultaneously collects bright field and spiral phase contrast imaging in the same frame, the bright field image corresponds to the central Airy pattern (such as 201.6 μm in diameter under 632.8 nm), the SPC image corresponds to the y-direction offset vortex pattern (such as 329.4 μm in diameter under 632.8 nm), and the digital image is directly output for observation and analysis.

[0057] As shown in Figure 3 , 4 The half-wave voltages at 450 nm, 520 nm and 632.8 nm for the liquid crystal double-mode imaging lens in the optical system are 5.35 V, 4.56 V and 3.87 V, respectively. The average optical transmittance under all measured wavelengths is more than 99.5%.

[0058] It can be understood that the displacement table can adjust the distance between the detection plane and the liquid crystal double-mode imaging lens module along the optical axis direction, and accurately adjust the detection plane of the camera equipment to the corresponding imaging focal plane according to the wavelength of the laser. The camera is used to acquire the first light wave and the second light wave, and output the corresponding images respectively. This design not only ensures the clarity and accuracy of bright field imaging and edge enhancement imaging, but also enhances the adaptability of the system to different wavelengths of laser through the adjustment function of the displacement table, further optimizes the imaging effect, and improves the versatility and flexibility of the system.

[0059] Reference is made to Figure 5 , Figure 5 is a schematic diagram of the theoretical simulation results of the point spread function of the liquid crystal double-mode imaging lens under 632.8 nm incident light.

[0060] Reference is made to Figure 6 , Figure 6 is a schematic diagram of the experimental measurement results of the point spread function of the liquid crystal double-mode imaging lens under 632.8 nm incident light.

[0061] Reference is made to Figure 7 , Figure 7 is a schematic diagram of the theoretical and experimental comparison results of the normalized intensity distribution of the central section of the bright field mode in the optical system.

[0062] Reference is made to Figure 8 , Figure 8 is a schematic diagram of the theoretical and experimental comparison results of the normalized intensity distribution of the central section of the spiral phase contrast mode in the optical system.

[0063] The technical scheme also provides an embodiment, a double-mode microscopic imaging system based on a single electrically controlled liquid crystal device, which mainly comprises a core electrically controlled liquid crystal device design (double-mode microscopic imaging lens), a point spread function, an incident light path, an imaging detection, and a preparation process system. In this system, the core electrically controlled liquid crystal device is the functional core for realizing double-mode imaging, integrating focusing, vortex modulation, and beam splitting functions; the incident light path module is responsible for providing suitable incident light (polarization state, size, wavelength); the imaging detection module is used for synchronously acquiring bright field and spiral phase contrast images.

[0064] In this embodiment, the double-mode microscopic imaging system comprises, in sequence along the optical axis, a 632.8 nm laser, a microscopic objective lens, a pinhole, a quarter-wave plate with an angle of 45° with the optical axis, a lens, a lens, a wheat epithelial cell, a 20x microscopic objective lens, a liquid crystal double-mode imaging lens, and a camera.

[0065] Through single-device multi-phase integration, electrically controlled wide-spectrum regulation, and 4f system-free synchronous detection, the synchronous acquisition of the "overall morphology + edge details" of the sample is realized, without mechanical switching and marking, which adapts to the needs of biomedical microscopic observation. The specific implementation steps of the system are as follows.

[0066] Step one: Phase design and integration of core electrically controlled liquid crystal device. Design and integrate the triple functional phase of "lens focusing phase, vortex modulation phase, grating beam splitting phase", in which the lens phase realizes beam focusing to form bright field image, the vortex phase introduces orbital angular momentum with topological charge q = 1 to realize edge enhancement, and the grating phase realizes spatial separation of two imaging beams in y direction to ensure that the bright field image (Airy pattern) and the spiral phase contrast image (vortex pattern) have no overlap.

[0067] Step two: Large size and high precision preparation of core device. Using DMD maskless step-by-step stitching lithography and liquid crystal light-controlled orientation technology, the complete phase pattern of 12.2472 mm x 12.2472 mm is divided into 9 sub-regions of 4.0824 mm x 4.0824 mm, and the step-by-step exposure is realized by precise translation (step size 4.0824 mm) along x and y axes; the single sub-phase is divided into 36 orders (5° polarization orientation angle per order), and 405 nm linearly polarized ultraviolet light is used for exposure (30 seconds per order), which guides the directional arrangement of liquid crystal molecules; then the liquid crystal cell is packaged.

[0068] Step three: Electrically controlled regulation for wide spectrum adaptation. For three representative wavelengths of 450 nm, 520 nm and 632.8 nm, by applying different half-wave voltages (5.35 V for 450 nm, 4.56 V for 520 nm, and 3.87 V for 632.8 nm), the liquid crystal device meets the phase delay half-wave condition, in which the phase delay changes the effective refractive index by voltage regulation of liquid crystal molecule pre-tilt angle, ensuring that the device has high diffraction efficiency (average 80.23%) and high transmittance (average over 99.5%) in a wide spectral range, and the electric response time is stable (92.36 ms for 450 nm, 79.23 ms for 520 nm, and 71.55 ms for 632.8 nm).

[0069] Step four: Verification and optimization of imaging performance. The resolution capability of the device is verified by using USAF 1951 resolution test target, and the smallest resolvable line width is 39.375 μm at 632.8 nm wavelength; imaging tests are performed on the letters "STU", Chinese characters "Shantou", clover pattern and wheat epidermal cells, and the results show that the bright field images at different wavelengths can clearly present the overall structure of the sample, the spiral phase contrast images can effectively enhance the edge contrast, and the intensity consistency of the two modes is good; through point spread function test, the experimental measured Airy spot diameter (201.6 μm at 632.8 nm wavelength) and vortex light diameter (329.4 μm at 632.8 nm wavelength) are highly consistent with the theoretical simulation, verifying the accuracy and stability of the system imaging.

[0070] Step five: optimization and adaptation of the incident light path. Use 450 nm, 520 nm, and 632.8 nm linearly polarized laser as the light source, and process it through the filtering and collimating system to remove stray light and output parallel light; convert the linearly polarized light into left-handed circularly polarized light through a quarter-wave plate to match the polarization modulation requirements of the device; according to the sample size, use a 4f scaling system (e.g., L2=250 mm, L3=50 mm to achieve 5x scaling, and L2=200 mm, L3=50 mm to achieve 4x scaling) to adjust the sample image size to 400-500 μm, ensuring that the incident light spot matches the effective area of the core device and avoiding edge light loss.

[0071] Step six: synchronous detection and acquisition of dual-mode imaging. Place the dual-mode microscopic imaging lens between the incident light path and the camera detector, and adjust the camera and the device's diffraction distance according to the focal plane positions of different wavelengths (0.135 m for 450 nm, 0.116 m for 520 nm, and 0.10 m for 632.8 nm); directly acquire the separated bright field and spiral phase contrast imaging in the same frame - the bright field image corresponds to the overall morphology of the sample (e.g., the outline of a wheat epidermal cell), and the spiral phase contrast imaging corresponds to the edge details of the sample (e.g., cell wall texture and transparent structure boundaries), without the need for additional 4f systems for Fourier filtering, which simplifies the optical path while avoiding multi-module alignment errors.

[0072] An example of the final dual-mode imaging is as follows: Figure 9 For the imaging results of wheat epidermal cells, the bright field imaging (clearly showing the overall morphology) and the spiral phase contrast imaging (highlighting the edge details) of the cells can be acquired synchronously without the need for labeling, which enables non-invasive observation of transparent biological samples and provides an efficient multi-modal imaging tool for biomedical diagnosis and life science research.

[0073] Please refer to Figure 10 , Figure 10 A step flowchart of an imaging method based on a liquid crystal dual-mode imaging lens.

[0074] The embodiment also provides an imaging method based on a liquid crystal dual-mode imaging lens, which is realized through any one of the above-mentioned optical systems based on a liquid crystal dual-mode imaging lens, and the imaging method comprises the following steps: S201, emitting laser light through the incident light path module and irradiating it to a target sample.

[0075] S202, after the light wave carrying sample information transmitted through the target sample is incident on the liquid crystal dual-mode imaging lens module, inputting a half-wave voltage corresponding to the light wave to the electrode area of the liquid crystal dual-mode imaging lens module.

[0076] S203, by controlling the half-wave voltage, so that the liquid crystal double-mode imaging lens module respectively performs the first type of phase modulation on the first part of the light wave to form a bright field imaging light path and the second type of phase modulation on the second part of the light wave to form an edge enhancement imaging light path at the same time point.

[0077] S204, using the imaging detection module to receive the first light wave output by the bright field imaging light path and the second light wave output by the edge enhancement imaging light path, and respectively generating corresponding bright field images and edge enhancement images.

[0078] In some embodiments, the optical system comprises a laser, a microscopic objective lens, a pinhole, a quarter-wave plate with an angle of 45° with the optical axis, a lens, a test sample, a lens, a lens, a liquid crystal double-mode imaging lens, and a camera arranged in sequence along the optical axis. The laser emitted by the laser is spatially filtered through the microscopic objective lens and the pinhole, and then generates circularly polarized light of a specific handedness with the help of the quarter-wave plate with an angle of 45° with the optical axis. The lens collimates the light beam, and then irradiates the hollow light-transmitting test sample as a target pattern. The lens and the lens are lenses with different focal lengths, and the main purpose is to perform anisometric scaling on the target object. The liquid crystal double-mode imaging lens is placed behind the image plane of the lens to perform double-mode imaging. Finally, the camera receives the double-mode imaging effect of the object at the position of 2f of the image plane of the liquid crystal double-mode imaging lens.

[0079] In an embodiment of the imaging method based on the liquid crystal double-mode imaging lens, the following steps are included: Step one: incident light preparation The light source emits linearly polarized light, which is converted into parallel light through the filtering and collimating unit (including an objective lens, a pinhole, and a collimating lens), and then is converted into left-handed circularly polarized light through a quarter-wave plate. Subsequently, the light beam is adjusted to be suitable for the sample size (400-500 μm) through the light beam scaling unit, and finally is incident on the liquid crystal double-mode imaging lens.

[0080] Step two: double-mode phase modulation According to the wavelength of the incident light, a corresponding half-wave voltage is applied to the liquid crystal double-mode imaging lens. The liquid crystal double-mode imaging lens focuses the light beam through the lens phase, modulates the edge information with the vortex phase, and separates the light spots with the grating phase, thereby outputting 0-order Gaussian light (for bright field imaging) and -1-order vortex light (for spiral phase contrast imaging).

[0081] Step three: synchronous imaging acquisition Adjust the displacement table so that the camera is located at the imaging focal plane. The camera synchronously acquires the images of the two light beams, wherein the bright field imaging is used to present the overall morphology of the sample, and the spiral phase contrast imaging is used to highlight the edge details of the sample. After the acquisition is completed, digital images are output for subsequent analysis.

[0082] Optionally, step four: wide spectrum switching If the wavelength needs to be switched (for example, from 632.8 nm to 450 nm), only the applied voltage (from 3.87 V to 5.35 V) and the diffraction distance of the CCD (from 0.10 m to 0.135 m) need to be adjusted, and no device needs to be replaced, so that the wavelength switching can be quickly completed.

[0083] This flow is particularly suitable for biological sample observation. For example, wheat epidermal cells are placed on the lens Fourier plane of the sample stage, and are magnified to 500 μm through a 20x eyepiece. Subsequently, through modulation by the liquid crystal bimodal imaging lens, the CCD synchronously acquires bright field imaging (showing the cell outline) and spiral phase contrast imaging (highlighting the cell wall texture). The entire process can achieve non-invasive observation of transparent samples without labeling.

[0084] It can be understood that the embodiment realizes synchronous acquisition through the innovative design of space-time parallelism. The core is that in step S203, the liquid crystal bimodal imaging lens module respectively applies two types of independent phase modulations to different parts of the incident light wave at the same time point: the first type of modulation forms a bright field imaging light path, retaining the overall transmission information of the sample; the second type of modulation constructs an edge enhancement light path, which enhances the detail contrast through spatial frequency domain filtering. This spatial beam splitting parallel processing mechanism avoids the time delay of traditional time division multiplexing, so that two types of modal images can be captured in a single frame exposure. The half-wave voltage input in step S202 ensures that the two types of modulations are accurately executed synchronously under a wide spectrum, and the synchronous reception of the double light paths by the imaging detection module in S204 realizes true synchronous acquisition from the physical layer. This method not only eliminates motion artifacts and dynamic sample information loss caused by time division switching, but also significantly improves the time resolution through one-step imaging, providing a reliable technical guarantee for high-speed application scenarios such as live observation.

[0085] In some embodiments, an imaging method based on a liquid crystal bimodal imaging lens further comprises: In response to an instruction to switch the imaging wavelength, by adjusting the half-wave voltage input to the liquid crystal bimodal imaging lens module and adjusting the diffraction distance between the camera device and the lens in the imaging detection module, a bright field image and an edge enhancement image corresponding to the target wavelength are generated.

[0086] It can be understood that the embodiment adjusts the half-wave voltage of the liquid crystal double-mode imaging lens module and the diffraction distance in the imaging detection module by responding to the instruction of switching the imaging wavelength, so that the system can dynamically adjust the imaging parameters according to different wavelength requirements. This design enables the system to quickly and accurately generate bright-field images and edge-enhanced images of corresponding wavelengths when switching wavelengths, ensuring that the imaging quality and clarity are not affected by the change of wavelengths. At the same time, this dynamic adjustment capability significantly enhances the versatility and practicality of the system in multi-wavelength imaging applications, making it better adapt to different samples and imaging requirements, further optimizing the function of simultaneously acquiring bright-field and edge-enhanced imaging information.

[0087] In some embodiments, an imaging method based on a liquid crystal double-mode imaging lens further comprises the step of calibrating the resolution capability of the optical system using a resolution test target, and the specific embodiments include: By measuring the first light wave output by the bright-field imaging light path, the Airy disk diameter is obtained; by measuring the second light wave output by the edge-enhanced imaging light path, the vortex light diameter is obtained; the Airy disk diameter and the vortex light diameter are compared with the corresponding theoretical simulation values respectively, and the score value of the optical system is determined according to the comparison result.

[0088] It can be understood that by measuring the Airy disk diameter output by the bright-field imaging light path and the vortex light diameter output by the edge-enhanced imaging light path, and comparing them with the theoretical simulation values, the actual resolution capability of the optical system in the two imaging modes can be quantitatively evaluated. This calibration method not only provides a scientific basis for the performance optimization of the system, but also ensures the accuracy and consistency of the imaging results. Through the determination of the score value, the user can intuitively understand the imaging quality of the system, so as to better apply it to actual scenes, further enhancing the applicability and credibility of the system in multiple scenes.

[0089] It can be understood that the contents in the above system embodiment are applicable to the present method embodiment, the function realized by the present method embodiment is the same as that of the above system embodiment, and the beneficial effects achieved by the present method embodiment are also the same as those achieved by the above system embodiment.

[0090] The terms "first", "second", "third", "fourth", and the like in the description of the specification and in the claims of the present application, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the use of the terms so construed herein is merely for convenience and brevity and that one of ordinary skill in the art will be able to devise examples of the present application with the features of the application in different orders and / or configurations without departing from the spirit or ambit of the application. Furthermore, the terms "comprise", "comprising", "include", "including", and "has", "having" and variants thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes an item or list of items that does not include other non-specified items or remove other non-specified items likewise falls within the scope of the present application. It will be appreciated that the terms "at least one", "one or more", "multiple", "two or more" and the like used herein are meant to encompass a quantity of one or more.

[0091] In several embodiments provided in the present application, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other manners. For example, the division of the apparatus embodiments described above is merely an example, and the units can be combined or integrated into another apparatus, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or in other forms.

[0092] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they can be located in one place, or distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments.

[0093] In addition, each functional unit in the various embodiments of the present application can be integrated into one processing unit, or each unit can exist physically, or two or more units can be integrated into one unit. The integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0094] While the application has been described in connection with very specific embodiments, it will be understood that the application is not limited to any of these details or embodiments or any special embodiment, but intends to cover all alternatives, modifications and equivalents as can be included within the scope of the application as defined by the appended claims when interpreted in accordance with the full scope of equivalents, rules of construction and the doctrine of equivalents under 35 U.S.C. § 112. Furthermore, the above description is intended to provide a useful description of the application, and is not intended to limit the application to the particular embodiments or examples described. It is being appreciated that those skilled in the art, who read the present disclosure, can easily conceive equivalents and modifications of the present application, and those are intended to be included within the scope of the present application.

Claims

1. An optical system based on liquid crystal bimodal imaging lens, characterized in that, The optical system comprises: An incident light path module configured to emit laser light to a target sample, the laser light being transmitted through the target sample; A liquid crystal dual-mode imaging lens module having at least two independently controllable electrode regions, configured to, after receiving light waves carrying sample information transmitted through the target sample, perform first-type phase modulation on a first portion of the light waves and second-type phase modulation on a second portion of the light waves at the same time point through corresponding electrode regions, to form a bright-field imaging light path and an edge-enhanced imaging light path, respectively; An imaging detection module configured to receive the first light waves transmitted through the bright-field imaging light path and the second light waves transmitted through the edge-enhanced imaging light path, to obtain bright-field image information and edge-enhanced image information.

2. The optical system of claim 1, wherein The liquid crystal dual-mode imaging lens module is further configured to: Perform grating beam-splitting phase modulation on the laser light, to output the first light waves and the second light waves and transmit them to corresponding regions in the imaging detection module after being spatially separated.

3. The optical system of claim 2, wherein, The specific manner of performing second-type phase modulation on the second portion of the light waves comprises: Performing annular high-pass filtering on the second light waves in the spatial frequency domain, to suppress low-frequency background light components of the second light waves and enhance high-frequency light components containing edge information of the target sample, to obtain an edge contrast-enhanced image projected by the second light waves.

4. The optical system of claim 3, wherein The liquid crystal dual-mode imaging lens module is further configured to: Input a corresponding half-wave voltage of the laser light, to maintain preset diffraction efficiency and transmittance in a wide spectral range.

5. The optical system of claim 1, wherein The incident light path module comprises, in sequence along an optical axis, a light source unit, a filtering and collimating unit, a polarization control unit, and a light beam scaling unit; The light source unit is configured to provide the laser light. The filtering and collimating unit is located on an exit light path of the light source unit and is configured to filter stray light and convert the laser light into parallel light. The polarization control unit is located on an exit light path of the filtering and collimating unit and is configured to adjust the parallel light into circularly polarized light. The light beam scaling unit is located on an exit light path of the polarization control unit and is configured to perform light beam diameter scaling processing on the circularly polarized light, so that a spot size of the circularly polarized light matches an effective modulation region of the liquid crystal dual-mode imaging lens module.

6. The optical system of claim 5, wherein, The light beam scaling unit is further configured to: When the target sample is a biological cell sample, magnify a sample image of the target sample to match the effective modulation region of the liquid crystal dual-mode imaging lens module according to a first magnification; When the target sample is a resolution test target, reduce a sample image of the target sample to match a minimum resolvable line width of the liquid crystal dual-mode imaging lens module according to a second magnification.

7. The optical system of claim 1, wherein The imaging detection module comprises a displacement stage and a camera device. The displacement stage is configured to adjust a distance between a detection plane of the imaging detection module and the liquid crystal dual-mode imaging lens module along an optical axis direction, and adjust the detection plane of the camera device to a corresponding imaging focal plane according to a wavelength of the laser light. The camera device is arranged on the displacement table and is configured to acquire the first light wave and the second light wave and output images corresponding to the first light wave and the second light wave, respectively.

8. An imaging method based on liquid crystal bimodal imaging lens, characterized in that, The imaging method is implemented by the liquid crystal bimodal imaging lens-based optical system according to any one of claims 1 to 7, and the imaging method comprises the following steps: The incident light path module is used to emit laser and irradiate the target sample; The light wave carrying sample information transmitted through the target sample is incident on the liquid crystal bimodal imaging lens module, and a half-wave voltage corresponding to the light wave is input to the electrode region of the liquid crystal bimodal imaging lens module; The half-wave voltage is controlled to enable the liquid crystal bimodal imaging lens module to perform first-type phase modulation on a first part of the light wave to form a bright-field imaging light path and perform second-type phase modulation on a second part of the light wave to form an edge-enhanced imaging light path at the same time point; The imaging detection module is used to receive the first light wave output by the bright-field imaging light path and the second light wave output by the edge-enhanced imaging light path, and generate corresponding bright-field images and edge-enhanced images, respectively.

9. The imaging method of claim 8, wherein, The imaging method further comprises the following steps: In response to an instruction to switch the imaging wavelength, the half-wave voltage input to the liquid crystal bimodal imaging lens module is adjusted, and the diffraction distance between the camera device and the lens in the imaging detection module is adjusted to generate bright-field images and edge-enhanced images corresponding to the target wavelength.

10. The imaging method of claim 8, wherein, The imaging method further comprises a step of calibrating the resolution capability of the optical system using a resolution test target, and the specific implementation comprises the following steps: The Airy disk diameter is obtained by measuring the first light wave output by the bright-field imaging light path; The vortex light diameter is obtained by measuring the second light wave output by the edge-enhanced imaging light path; The Airy disk diameter and the vortex light diameter are compared with corresponding theoretical simulation values, respectively, and a score value of the optical system is determined according to a comparison result.

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