Dark field speckle illumination super-resolution imaging system based on planar device

Abstract

The invention discloses a dark field speckle illumination super-resolution imaging system based on a planar device, and belongs to the field of super-resolution dark field imaging, the system uses a 633nm laser light source to emit a strong coherence light beam with the wavelength of 633nm, the strong coherence light beam enters the planar device through a multimode optical fiber bundle, the emitted laser enters a titanium dioxide scattering layer to be scattered, and the light beam is emitted into the planar device through a light source. The one-dimensional photonic crystal screens speckles of which the numerical aperture is greater than 0.6, and the speckles pass through the one-dimensional photonic crystal and illuminate the sample; scattered light emitted by the illuminated sample reaches the image plane detector to form a dark field speckle pattern of the sample; the multi-mode optical fiber bundle is vibrated through the vibrator to change the phase of the incident strong-coherence light beam, and a plurality of different dark-field speckle patterns are recovered to obtain a high-resolution dark-field image. The device is high in imaging resolution, compact in structure, easy to integrate and simple to operate, does not need a strict alignment process, and realizes high-contrast super-resolution dark field imaging and surface wave imaging.

Description

Technical Field

[0001] The invention belongs to the field of super-resolution dark field imaging, and in particular relates to a dark field speckle illumination super-resolution imaging system based on a planar device. Background Art

[0002] Microscopic imaging technology is the most direct means for people to understand the microscopic world. Optical microscopic imaging technology presents the image of the microscopic world directly in front of our eyes. It is the most intuitive and most commonly used microscopic technology among all microscopic imaging technologies. Darkfield microscopic imaging technology is a high-contrast, wide-field, label-free imaging technology. It illuminates the sample by obliquely incident light at a large angle so that the imaging objective only collects the scattered light of the sample. Therefore, in the presented image, the illuminated sample is bright and the background is dark. Since the illumination light is not collected by the imaging objective, its imaging contrast is much higher than that of brightfield optical microscopy. However, dark-field imaging microscopy technology has great limitations in practical applications. For example, traditional dark-field microscopes require the use of a special condenser to enable illumination light to be incident on the sample at a large angle. The large size of the condenser increases the volume of the imaging system. The numerical aperture of condenser illumination requires that the collimation of the incident light beam be very high in order to achieve the expected uniform illumination effect, which increases the operational complexity of the system. The imaging resolution of traditional dark-field illumination is limited by the diffraction limit of the imaging system and cannot achieve super-resolution imaging, which limits its application. Since the condenser illuminates the sample in a focused manner, its illumination field of view is small. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a dark field speckle illumination super-resolution imaging system based on a planar device, which uses a coherent light beam to pass through a titanium dioxide scattering layer, and the scattered light interferes with each other to form a speckle pattern. The one-dimensional photonic crystal in the planar device performs angle screening on the propagation waves of the speckle to achieve large-angle dark field speckle illumination. The scattered light of the illuminated sample is collected by the imaging system to form a speckle pattern image of the sample. Different speckle pattern illuminations are changed by vibrating the vibrator, and the imaging system records different sample speckle patterns. Different speckle patterns are calculated by the conjugate gradient algorithm to obtain high-resolution dark field images.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A dark field speckle illumination super-resolution imaging system based on a planar device, the system comprising: an image plane detector, an imaging tube lens, an imaging objective lens, a planar device, a 633nm laser light source, and a vibrator, wherein the planar device comprises a one-dimensional photonic crystal, a titanium dioxide scattering layer, a multimode optical fiber bundle, and a 300nm thick gold film stacked in sequence from top to bottom;

[0006] The 633nm laser light source emits a strong coherent light beam with a wavelength of 633nm, the strong coherent light beam is incident on the planar device through a multimode optical fiber bundle, the emitted laser is incident on the titanium dioxide scattering layer for scattering, the scattered strong coherent light beams interfere with each other to form speckles, and are incident on the one-dimensional photonic crystal, the one-dimensional photonic crystal screens speckles with a numerical aperture greater than 0.6 to pass through the one-dimensional photonic crystal and illuminate the sample on the one-dimensional photonic crystal; the scattered light emitted by the illuminated sample is collected by the imaging objective lens and passes through the imaging tube lens to reach the image plane detector to form a dark field speckle pattern of the sample;

[0007] By vibrating the multimode fiber bundle with a vibrator to change the phase of the incident strong coherence light beam, multiple different dark-field speckle patterns are obtained. The multiple different dark-field speckle patterns are restored using the conjugate gradient algorithm to obtain a high-resolution dark-field image that exceeds the diffraction limit.

[0008] Furthermore, the 300 nm thick gold film is used to reflect the strong coherent light beam scattered to the lower layer back to the titanium dioxide scattering layer.

[0009] Furthermore, the one-dimensional photonic crystal is composed of alternately stacked SiO2 and Si3N4 nanofilms.

[0010] Furthermore, the numerical aperture of the imaging objective lens is 0.6, and the magnification is 40 times.

[0011] Furthermore, the titanium dioxide scattering layer is prepared by spin coating titanium dioxide particles with a size of 60 nm on a clean cover glass, and the film formed by the titanium dioxide particles is about 2 μm.

[0012] Furthermore, one end of the multimode optical fiber bundle is randomly adhered to the upper surface of a 300 nm thick gold film using α-ethyl cyanoacrylate.

[0013] The beneficial effects of the present invention are:

[0014] 1. High spatial resolution imaging: After passing through the titanium dioxide scattering layer, the coherent light beam of the present invention is scattered into various angles and interferes with each other to form speckles. The one-dimensional photonic crystal regulates the speckle emission angle to form dark-field speckle illumination. Through the conjugate gradient algorithm recovery, high-resolution dark-field imaging beyond the diffraction limit can be obtained.

[0015] 2. Wide-field imaging: The illumination area of ​​the present invention is determined by the size of the planar illumination device and the multimode fiber bundle arrangement. In theory, the illumination area can be the entire planar illumination device, and wide-field imaging can be achieved by combining with different imaging objective lenses.

[0016] 3. Simple device: The microscope system of the present invention is composed of an ordinary upright microscope, a plane lighting device and a light source. The coherent light is directly coupled into the plane illuminator through a multimode optical fiber bundle, which is convenient for non-professionals to operate.

[0017] 4. High integration: The coherent light beam of the present invention is transmitted by a multimode optical fiber waveguide, the light beam is not transmitted in free space, and the size of the planar device is a micron-level device, which greatly reduces the volume of the system and realizes integration.

[0018] 5. Multifunctional lighting: Due to the band structure of the all-dielectric one-dimensional photonic crystal, the incident 532nm strong coherent light source can achieve total internal reflection illumination and realize high-resolution surface imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a dark-field speckle illumination super-resolution imaging system based on a planar device of the present invention;

[0020] Figure 2 It is a schematic diagram of the lighting principle of the planar device of the present invention;

[0021] Figure 3 This is a schematic diagram of the application results of a dark-field speckle illumination super-resolution imaging system based on a planar device of the present invention, wherein a is the result of the average addition of 200 sample speckle images obtained using the imaging system; b is the result of dark-field imaging after restoration using the conjugate gradient algorithm; and c is the actual image of the sample observed under an electron microscope.

[0022] Reference numerals:

[0023] 1. Image plane detector; 2. Imaging tube lens; 3. Imaging objective lens; 4. Planar device; 5. 633nm laser light source; 6. Vibrator; 7. One-dimensional photonic crystal; 8. Titanium dioxide scattering layer; 9. Multimode fiber bundle; 10. 300nm thick gold film. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] like Figure 1As shown, a dark field speckle illumination super-resolution imaging system based on a planar device of the present invention comprises an image plane detector 1, an imaging tube lens 2, an imaging objective lens 3, a planar device 4, a 633 nm laser light source 5, and a vibrator 6. Figure 2 As shown, the planar device 4 includes one-dimensional photonic crystals 7 for regulating the speckle emission angle stacked in sequence from top to bottom, a titanium dioxide scattering layer 8 for scattering the incident light into various angles, a multimode optical fiber bundle 9 for transmitting coherent light beams, and a 300nm thick gold film 10 for improving light utilization efficiency. One end of the multimode optical fiber bundle 9 is randomly adhered to the upper surface of the 300nm thick gold film 10 using α-ethyl cyanoacrylate.

[0027] The principle of the technical solution of the present invention is: a highly coherent light beam is transmitted through a multimode optical fiber bundle 9 to be incident on a planar device 4 to form a highly integrated lighting device. The titanium dioxide scattering layer 8 in the planar device 4 is used to scatter the incident light into lights of various angles, and interfere with each other to form speckles. The energy band structure of the one-dimensional photonic crystal 7 above the planar device 4 is designed to adjust the emission angle of the speckle to form a large-angle dark-field speckle illumination. Only the scattered light information of the illuminated sample is collected by the imaging system to form a dark-field speckle pattern of the sample. The multimode optical fiber bundle 9 is vibrated by a vibrator 6 to change the phase of the incident light so that the illumination speckle pattern changes, and the imaging system records the sample speckle pattern of different dark-field speckle illuminations. The image is restored using a conjugate gradient algorithm to obtain a dark-field image with high contrast and high resolution.

[0028] Specifically, the 633nm laser light source 5 emits a strong coherent light beam with a wavelength of 633nm, and the light beam is transmitted into the planar device 4 through the multimode optical fiber bundle 9. After the incident light beam is emitted from the multimode optical fiber bundle 9, it is incident on the titanium dioxide scattering layer 8 and scattered at various angles. The scattered light interferes with each other to form speckles and is incident on the one-dimensional photonic crystal 7. The one-dimensional photonic crystal 7 screens the incident speckle angle, and only light with a numerical aperture greater than 0.6 can pass through the one-dimensional photonic crystal 7. Therefore, after passing through the one-dimensional photonic crystal 7, a large-angle dark field speckle can be formed, and the sample on the one-dimensional photonic crystal 7 can be illuminated. The illuminated sample emits scattered light, which is collected by the imaging objective lens 3 with a numerical aperture of 0.6 and sequentially passes through the imaging tube lens 2 to reach the image plane detector 1 to form a dark field speckle pattern of the sample. Different speckle pattern illumination can be obtained by vibrating the multimode optical fiber bundle 9 with the vibrator 6 to change the phase of the incident light, and the image plane detector 1 is used to sequentially record the different dark field speckle patterns of the corresponding samples, totaling 200. The dark field speckle patterns of 200 samples are restored using the conjugate gradient algorithm to obtain high-resolution dark field images that exceed the diffraction limit.

[0029] The 633nm laser light source 5 is a strong coherent light source. After being transmitted and incident on the titanium dioxide scattering layer 8, the scattered light interferes with each other to form speckles. After the speckle pattern is incident on the one-dimensional photonic crystal 7, since the one-dimensional photonic crystal 7 can screen the transmittance of the incident light beam, only light with a numerical aperture greater than 0.6 can pass through the one-dimensional photonic crystal 7, and light with a numerical aperture less than 0.6 is reflected by the one-dimensional photonic crystal 7 back to the titanium dioxide scattering layer 8 and scattered again to the one-dimensional photonic crystal 7. The scattered light with a numerical aperture greater than 0.6 will interfere with each other on the surface of the one-dimensional photonic crystal 7 to form a large-angle dark field speckle illumination. The imaging objective lens 3 has a collection numerical aperture smaller than the illumination numerical aperture, so the imaging objective lens 3 can only collect the scattered light of the object, but not the illumination light, forming a dark field imaging. The imaging objective lens 3 used here has a numerical aperture of 0.6 and a magnification of 40 times. The pure scattered light of the sample is collected by the imaging objective lens 3 and reaches the imaging tube lens 2 and is finally recorded on the image plane detector 1.

[0030] The vibrator 6 is a mechanical vibration that can disturb the multimode fiber bundle 9, causing the phase of the transmitted coherent light beam to change, thereby changing the speckle pattern emitted from the one-dimensional photonic crystal 7. Different speckle patterns will be recorded in sequence by the image plane detector 1. The total number of recorded images is 200. The 200 images can be restored to a high-resolution dark field image beyond the diffraction limit using the conjugate gradient algorithm.

[0031] The one-dimensional photonic crystal 7 controls the light flow by processing multiple layers of nanofilms with alternating high and low refractive indices, manipulating the transmission and reflection of different light wave vectors to allow light beams greater than a certain wave vector to pass through. By changing the refractive index and thickness of each layer, a planar device substrate supporting different wavelengths and different emission angles can be set. The multi-one-dimensional photonic crystal 7 is composed of SiO2 and Si3N4 nanofilms, a total of 15 pairs. Among them, the one-dimensional photonic crystal 7 is composed of alternating layers of Si3N4 and SiO2 media, and is manipulated to meet the requirements of generating a light beam with a numerical aperture greater than 0.6 to pass through.

[0032] The titanium dioxide scattering layer 8 is prepared by spin coating titanium dioxide particles with a size of 60 nm on a clean cover glass. The thin film formed by the titanium dioxide particles is about 2 μm, so that the incident coherent light is scattered by the titanium dioxide scattering layer 8 and interferes with each other to form a speckle pattern that is incident on the one-dimensional photonic crystal 7.

[0033] The imaging tube lens 2, the air objective lens 3, the image plane detector 1, and the planar device 4 constitute a dark field speckle illumination super-resolution imaging system with a large field of view, and the above devices are coaxially placed.

[0034] like Figure 3As shown, it is the effect of imaging a polystyrene sphere with a diameter of 200nm using the dark field speckle illumination super-resolution imaging system based on a planar device of the present invention. Among them, a is the result of the average addition of 200 sample speckle images obtained using the system, that is, the effect of traditional dark field imaging. The image has the advantage of high contrast but the disadvantage of low resolution; b is the result of dark field imaging after restoration by the conjugate gradient algorithm. It can be seen that the spatial positions of two adjacent particles can be clearly distinguished, so the image has the advantage of high resolution; c is the real image of the sample observed under an electron microscope. It can be seen that the two particles are 340nm apart. Theoretically, an objective lens with a numerical aperture of 0.6 can only distinguish 527nm, so the imaging resolution of the system is improved by 1.5 times.

[0035] In summary, the purpose of the present invention is to overcome the shortcomings of low imaging resolution, single illumination function, bulky size and high cost of traditional dark field imaging microscopes, and propose a dark field speckle illumination super-resolution imaging system based on planar devices. The system has high imaging resolution, compact structure, easy integration, simple operation, no strict alignment process, and realizes high-contrast super-resolution dark field imaging and surface wave imaging.

[0036] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dark field speckle illumination super-resolution imaging system based on planar devices, characterized in that: The system comprises: an image plane detector (1), an imaging tube lens (2), an imaging objective lens (3), a planar device (4), a 633 nm laser light source (5), and a vibrator (6), wherein the planar device (4) comprises a one-dimensional photonic crystal (7), a titanium dioxide scattering layer (8), a multimode optical fiber bundle (9), and a 300 nm thick gold film (10) stacked in sequence from top to bottom; The 633nm laser light source (5) emits a strong coherent light beam with a wavelength of 633nm, the strong coherent light beam is incident on the planar device (4) through a multimode optical fiber bundle (9), the emitted laser is incident on the titanium dioxide scattering layer (8) for scattering, the scattered strong coherent light beams interfere with each other to form speckles, which are incident on the one-dimensional photonic crystal (7), the one-dimensional photonic crystal (7) screens speckles with a numerical aperture greater than 0.6 to pass through the one-dimensional photonic crystal (7) and illuminate a sample on the one-dimensional photonic crystal (7); the scattered light emitted by the illuminated sample is collected by the imaging objective lens (3) and passes through the imaging tube lens (2) to reach the image plane detector (1) to form a dark field speckle pattern of the sample; A vibrator (6) vibrates a multimode optical fiber bundle (9) to change the phase of an incident strong coherence light beam to obtain a plurality of different dark field speckle patterns, and a conjugate gradient algorithm is used to restore the plurality of different dark field speckle patterns to obtain a high-resolution dark field image that exceeds the diffraction limit.

2. A dark field speckle illumination super-resolution imaging system based on a planar device according to claim 1, characterized in that: The 300 nm thick gold film (10) is used to reflect the strong coherent light beam scattered to the lower layer back into the titanium dioxide scattering layer (8).

3. The dark field speckle illumination super-resolution imaging system based on planar devices according to claim 1, characterized in that: The one-dimensional photonic crystal (7) is composed of SiO2 and Si3N4 nanofilms stacked alternately.

4. The dark field speckle illumination super-resolution imaging system based on planar devices according to claim 1, characterized in that: The numerical aperture of the imaging objective lens (3) is 0.6, and the magnification is 40 times.

5. The dark field speckle illumination super-resolution imaging system based on planar devices according to claim 1, characterized in that: The titanium dioxide scattering layer (8) is prepared by spin coating titanium dioxide particles with a size of 60 nm on a clean cover glass, and the film formed by the titanium dioxide particles is about 2 μm.

6. The dark field speckle illumination super-resolution imaging system based on a planar device according to claim 1, characterized in that: One end of the multimode optical fiber bundle (9) is randomly adhered to the upper surface of a 300 nm thick gold film (10) using α-ethyl cyanoacrylate.

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