Stereoscopic microscopic imaging device based on multi-focal super surface

Abstract

The application discloses a stereoscopic microscopic imaging device based on a multifocal super surface, comprising a laser device, a plurality of plano-convex lenses, a super surface, a microscopic objective lens, a sleeve lens and a camera arranged along a laser excitation emission direction; the standard sample is arranged between the plano-convex lens and the super surface; and the super surface is composed of a substrate and a super surface structure array integrating a plurality of focusing lens phase distributions. Through the above scheme, the application has the advantages of simple structure, shortened imaging time and the like, and has high practical value and popularization value in the application field of super surface imaging technology.

Description

Technical Field

[0001] This invention relates to the field of metasurface imaging technology, and in particular to a stereomicroscopic imaging device based on a multifocal metasurface. Background Technology

[0002] Imaging is an effective way to record landscapes and discover the world. Among these, stereoscopic imaging is a particularly attractive technique for recording and displaying complex objects. Based on layer-by-layer scanning, a series of stereoscopic imaging techniques have been developed, including light field cameras or microscopes, confocal microscopes, and optical coherence tomography (OCT). Light field cameras or microscopes are one technique that acquires three-dimensional images in a short time by recording the direction information of light. However, their resolution is limited by the number of lenses and optical design. Confocal microscopy is the benchmark for high-resolution stereoscopic microscopy, and one of its bottlenecks is imaging speed. Additionally, OCT is performed using mechanical devices such as scanning galvanometers, resulting in long scanning and successive imaging times. Another bottleneck in three-dimensional microscopy is the cost of the hardware. For example, confocal microscopy requires a high-quality microscope equipped with an infinity optical system and high numerical aperture objectives, a galvanometer, a nanoplatform, a pinhole camera, and a high-sensitivity detector. While adding diffractive optics can scan multiple planes simultaneously, this reduces imaging time but makes the system more expensive. Both the market and scientific research require efficient and economical three-dimensional imaging elements.

[0003] Metasurfaces are a new type of ultrathin optical device capable of integrating complex optical operations, and their imaging capabilities have been studied for several years. Thanks to new manufacturing technologies, metasurfaces can achieve efficiencies exceeding 80%, which is acceptable for imaging without complex filtering systems. By integrating a series of lenses with different focal lengths into a single metasurface, information from different planes can be collected simultaneously using the metalens.

[0004] Therefore, there is an urgent need to propose a multifocal metasurface stereomicroscopy imaging device with a simple structure and shortened imaging time. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a stereomicroscopic imaging device based on a multifocal metasurface. The technical solution adopted by the present invention is as follows:

[0006] A stereomicroscopic imaging device based on a multifocal metasurface is used to image a standard sample. It includes a laser arranged along the laser excitation and emission direction, several plano-convex lenses, a metasurface, a microscope objective, a sleeve lens, and a camera. The standard sample is placed between the plano-convex lenses and the metasurface. The metasurface is composed of a substrate and a metasurface structure array integrating multiple focusing lenses with phase distribution.

[0007] The process of setting up the metasurface is as follows:

[0008] Step S1: Calculate the phase distribution after integrating multiple focusing lenses using formula (1), the expression of which is:

[0009] (1)

[0010] in,( () represents the coordinates of the focusing lens; Represents the wave vector in a vacuum; This represents the focal length of the i-th plano-convex lens.

[0011] Step S2: Combine the phase distribution obtained in step S1 after integrating multiple focusing lenses with the off-axis system to focus light from one point on the axis to another point off-axis, thereby separating the overlapping images after multi-focus focusing. Calculate the ideal phase distribution of the metasurface using formula (2), whose expression is:

[0012] (2)

[0013] in, This represents the deflection wave vector of the i-th plano-convex lens on the x-axis; This represents the deflection wave vector of the i-th plano-convex lens on the y-axis.

[0014] Step S3: After combining the ideal phase distribution of the metasurface obtained in step S2 with the actual substrate thickness and the influence of the introduced off-axis amount on the phase distribution, the final phase distribution of the metasurface is calculated using formula (3), which is expressed as follows:

[0015]

[0016] in, This represents the working distance of the i-th plano-convex lens; Indicates the imaging distance; n represents the refractive index of the substrate; This represents the displacement of the imaging center of the i-th plano-convex lens along the x-axis; This represents the offset of the imaging center of the i-th plano-convex lens along the y-axis.

[0017] Furthermore, the plano-convex lens includes a first plano-convex lens, a second plano-convex lens, and a third plano-convex lens; a pinhole filter is disposed between the first plano-convex lens and the second plano-convex lens. The 4f system formed by the second and third plano-convex lenses allows for convenient adjustment of the field of view through the illumination source composed of the 4f system.

[0018] Preferably, the laser is a 632.8nm helium-neon laser.

[0019] Preferably, the thickness of the substrate of the metasurface is 600 μm, and the off-axis distance of the metasurface is 20°.

[0020] The optical principle of the stereomicroscopic imaging device is as follows:

[0021] The key to stereoscopic imaging in optical microscopy lies in changing the relative position of the focal plane and the sample. By adjusting the height of the objective lens or stage, a two-dimensional image is obtained at each height, and these images are superimposed to form a stereoscopic pattern. This technique introduces off-axis quantities into a metasurface integrating multiple focusing lenses, allowing a single metasurface to focus images at different focal lengths to different locations in space through a single imaging process. Furthermore, a beam-shrinking system composed of a first plano-convex lens and a pinhole filter behind the laser focuses the laser beam; a 4f system composed of a second and third plano-convex lens adjusts the field of view; and a microscope system composed of a microscope objective, a fourth plano-convex lens, a subsequent sleeve lens, and a camera magnifies and images the output beam from the metasurface. These three parts are basic optical path components and do not require specific positions; the standard sample only needs to be placed at the focal length of the metasurface. If the output beam size from the metasurface is appropriate, the microscope system can be omitted, and the image can be directly imaged from the output beam.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) By setting up a metasurface and introducing an off-axis system, the present invention focuses images with different focal lengths onto different positions in the same plane, thereby separating overlapping images. Information from different planes can be collected in one imaging, greatly reducing imaging time.

[0024] (2) By setting a first plano-convex lens, a second plano-convex lens, and a third plano-convex lens, and utilizing a 4f system composed of the second and third plano-convex lenses, the field of view can be easily adjusted through the illumination source composed of the 4f system. In addition, the present invention uses a pinhole filter to remove high-frequency noise.

[0025] (3) This invention optimizes the phase distribution of the metasurface by combining the actual substrate thickness and the effect of introducing off-axis amount on the phase distribution. Before optimization, introducing off-axis amount would reduce the output light spot intensity. After jointly optimizing the substrate thickness and off-axis amount, the output light spot intensity can be greatly improved. Figure 2 As shown in (b) and 2(c).

[0026] In summary, this invention has advantages such as simple structure and shortened imaging time, and has high practical and promotional value in the field of metasurface imaging technology. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope of protection. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a traditional focusing lens after the introduction of off-axis measurement.

[0029] Figure 2 The figures show the phase curves for three cases in this invention: without substrate correction, with substrate correction, with substrate correction, and off-axis correction, as well as the point spread function (PSF) when different off-axis angles are added before and after substrate correction.

[0030] Figure 3 This is a schematic diagram of the structure of the present invention.

[0031] Figure 4 These are experimental images of the present invention collected on different planes.

[0032] Figure 5 This is a schematic diagram of the metasurface structure of the present invention.

[0033] In the above figures, the component names corresponding to the reference numerals are as follows:

[0034] 1. Laser; 2. First plano-convex lens; 3. Pinhole filter; 4. Second plano-convex lens; 5. Third plano-convex lens; 6. Standard sample; 7. Metasurface; 8. Microscope objective; 9. Sleeve lens; 10. Camera. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0036] Example

[0037] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0038] The terms "first" and "second," etc., used in the specification and claims of this embodiment are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0039] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0040] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units means two or more processing units; multiple systems means two or more systems.

[0041] like Figure 1 As shown, the ordinary focusing lens described in this embodiment introduces an off-axis amount to focus light from one on-axis point to another on-axis point, causing the entire image to shift and thus separating the overlapping images after being focused by multiple focusing lenses. Wherein, Figure 1 (a) represents the image formed when an ordinary focusing lens focuses the incident light rays to a point on the optical axis. Figure 1 (b) indicates that by introducing an off-axis amount, light can be focused to another point off-axis for imaging. Figure 1 (c) indicates that different planar objects are simultaneously focused to different positions in space, thereby achieving imaging of different spatial positions in a single operation.

[0042] The multifocal metasurface described in this embodiment, due to the substrate thickness and the introduction of off-axis adjustment, causes defocusing in high-NA imaging systems because the phase gradient contributes differently to the center and edge light. After comparing the phase curves under three conditions—without substrate correction, with substrate correction, and with off-axis correction—and correcting for these factors, the metasurface, with a substrate thickness of 600 μm, achieves a final optimized off-axis adjustment of 20° and a phase distribution as follows:

[0043]

[0044] in, Represents the wave vector in a vacuum; This represents the working distance of the i-th plano-convex lens; Indicates the imaging distance; n represents the refractive index of the substrate; This represents the displacement of the imaging center of the i-th plano-convex lens along the x-axis; This represents the offset of the imaging center of the i-th plano-convex lens along the y-axis; () represents the coordinates of the focusing lens.

[0045] like Figure 3 As shown, the stereomicroscopic imaging device based on a multifocal metasurface in this embodiment images a standard sample. It includes a laser 1, a first plano-convex lens 2, a pinhole filter 3, a second plano-convex lens 4, a third plano-convex lens 5, a metasurface 7, a microscope objective 8, a sleeve lens 9, and a camera 10, arranged along the laser excitation and emission direction. The standard sample 6 is placed between the third plano-convex lens 5 and the metasurface 7. The laser 1 is a 532nm helium-neon laser. First, after passing through a pinhole filter, the field of view is limited to 20° using a 4f system composed of the second and third plano-convex lenses as the illumination system. Within the pinhole, the field of view can be easily adjusted using this illumination system. The standard sample and the metasurface are mounted on two separate triaxial platforms, allowing for easier adjustment of the distance between the two samples and the imaging distance. The microscopy system (i.e., microscope objective 8) uses a 60X NA 0.85 microscope objective and is calibrated with a cover glass (0.17mm). Furthermore, it should be noted that the structure of the metasurface 7 in this embodiment is a well-established technology and will not be described in detail here. Figure 5 As shown.

[0046] like Figure 4 As shown, the multifocal metasurface in this embodiment integrates three lenses with focal lengths of 55mm and 100mm respectively. 60 and 65 The off-axis angle is set to 20°. In this embodiment, when the standard sample is placed at the three focal lengths designed for the metasurface, the pattern is clear relative to the designed location, but blurry at other locations. Figure 4 (f) represents the standard sample pattern. Figure 4 (g) indicates that the sample is 55 cm away from the metasurface. Patterns captured by a camera at that time. Figure 4 (h) indicates that the sample is 60 mm away from the metasurface. Patterns captured by a camera at that time. Figure 4 (i) indicates that the sample is 65 cm away from the metasurface. Patterns captured by a camera.

[0047] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any changes made based on the design principles of the present invention, or any non-creative modifications made thereon, shall fall within the scope of protection of the present invention.

Claims

1. A stereomicroscopic imaging device based on a multifocal metasurface for imaging a standard sample (6), characterized in that, It includes a laser (1) arranged along the laser excitation and emission direction, three plano-convex lenses, a metasurface (7), a microscope objective (8), a sleeve lens (9), and a camera (10); the standard sample (6) is placed between the plano-convex lenses and the metasurface (7); the metasurface (7) is composed of a substrate and a metasurface structure array integrating multiple focusing lenses with phase distribution; Phase distribution of the metasurface (7) Satisfy the following formula: in, Represents the wave vector in a vacuum; This represents the working distance of the i-th plano-convex lens; Indicates the imaging distance; n represents the refractive index of the substrate; This represents the offset of the imaging center of the i-th plano-convex lens along the x-axis; This represents the offset of the imaging center of the i-th plano-convex lens along the y-axis; () represents the coordinates of the focusing lens; where i is 1-3; The three plano-convex lenses include a first plano-convex lens (2), a second plano-convex lens (4), and a third plano-convex lens (5); a pinhole filter (3) is provided between the first plano-convex lens (2) and the second plano-convex lens (4); The thickness of the substrate of the metasurface (7) is 600 μm, and the off-axis distance of the metasurface (7) is 20°.

2. The stereomicroscopic imaging device based on a multifocal metasurface according to claim 1, characterized in that, The laser (1) is a 632.8nm helium-neon laser.

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