CN115793222A - Imaging method and imaging system based on multi-azimuth illumination - Google Patents

Abstract

The invention discloses an imaging method based on multi-azimuth illumination, which comprises the following steps: receiving P polarized light with different azimuth angles; p polarized light with different azimuth angles passes through an interference imaging main light path to obtain a plurality of surface plasma interference images which are in one-to-one correspondence with the P polarized light with different azimuth angles; and carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the P polarized light with different azimuth angles one by one to obtain isotropic images. The invention discloses an imaging system based on multi-azimuth illumination, which comprises: for performing a multi-azimuth illumination based imaging method. The invention utilizes multi-azimuth polarized illumination to obtain a plurality of surface plasma interference images which correspond to the P polarized light of different azimuths one by one, and carries out image reconstruction to obtain isotropic images, and the images have high definition and are not distorted.

Description

Imaging method and imaging system based on multi-azimuth illumination

Technical Field

The invention belongs to the technical field of optical microscope super-resolution surface plasma microscopic imaging, and particularly relates to an imaging method and an imaging system based on multi-azimuth illumination.

Background

Surface Plasmon Resonance (SPR) is a label-free detection method, when the wave vector of incident light wave matches with that of metal Surface plasma, two-wave Resonance occurs, most energy of incident light is absorbed by the Surface plasma wave, so that the intensity of reflected light is sharply reduced, and the SPR is very sensitive to the refractive index of the metal interface. Since its first proposal in 1990, SPR has proven to be one of the strongest techniques for determining the specificity, affinity and kinetic parameters of macromolecules in the binding process of many bond types, including protein-protein, protein-DNA, enzyme-substrate or inhibitor, receptor-drug, etc. This optical detection technique measures the refractive index change near a thin metal layer (i.e., gold, silver, or aluminum film) with a detection range of about 300nm at the metal interface, which has been a suitable and reliable platform for clinical analysis of biomolecular interactions over the last three decades.

In general, the wave vector of the surface plasmon wave is larger than that of the light wave, and therefore the surface plasmon wave propagating along the interface cannot be excited directly by the light wave. In order to excite surface plasmon waves, some special structures need to be introduced to achieve wave vector matching, and the most common and simplest structure is based on a prism coupling method, also called a Kretschmann structure. The metal film is directly plated on the prism surface, when the incident light reaches a certain angle, the incident light can be totally reflected at the metal-prism interface, when the evanescent wave generated by total reflection is matched with the wave vector of the surface plasma wave, the energy of the light is transferred to the surface plasma, so that the surface plasma wave is excited, the intensity of the detected reflected light is reduced rapidly, and the incident angle is also called as a resonance angle. When the refractive index of the metal interface changes, the resonance angle also shifts correspondingly, so as to reflect the intermolecular interaction process on the chip surface.

The traditional surface plasma microscope adopts a coherent light inclined illumination imaging mode with a single azimuth angle, namely, the longitudinal spatial resolution along the azimuth direction of incident light is limited by the propagation distance of surface plasma waves, and the transverse spatial resolution along the azimuth direction of vertical incident light is limited by the optical aperture of an objective lens system, so that the spatial resolution is insufficient and anisotropic (the transverse resolution is about 300nm, and the longitudinal resolution is micron order), and image blurring and distortion are caused.

Disclosure of Invention

The invention provides an imaging method and an imaging system based on multi-azimuth illumination, and aims to solve the technical problems of insufficient spatial resolution and anisotropy of a surface plasma microscopic imaging technology.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

in a first aspect, the invention discloses an imaging method based on multi-azimuth illumination, comprising the following steps:

s100, receiving incident light with different azimuth angles;

s200, obtaining a plurality of surface plasma interference images in one-to-one correspondence by incident light corresponding to different azimuth angles through an interference imaging main light path;

s300, carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the incident light with different azimuth angles one by one to obtain isotropic images.

The further improved scheme is as follows: the incident light is P polarized light.

The further improved scheme is as follows: in step S100, the P polarized light with different azimuth angles is formed by:

the parallel laser is converted into P polarized light through the polarization unit, and the polarization direction of the P polarized light is changed through continuous rotation of the polarization unit, so that the P polarized light with a plurality of different azimuth angles is obtained.

The further improved scheme is as follows: the interference imaging main optical path comprises an objective lens, an imaging chip for placing a sample and an imaging unit;

the objective lens receives incident light with different azimuth angles, and the incident light irradiates an imaging chip with a sample through the objective lens according to a set angle so as to excite the metal interface plasma of the imaging chip to generate surface plasma resonance, and the scattered light of the sample and the reflected light of the metal interface are coupled back and emitted out to be collected by the objective lens;

and (3) collecting sample scattered light and reflected light of a metal interface by the objective lens, and obtaining a surface plasma interference image through interference imaging.

The further improved scheme is as follows: in step S300, performing image reconstruction on a plurality of surface plasmon interference images corresponding to incident light with different azimuth angles one to one, to obtain an isotropic image, which specifically includes:

obtaining a sample information pixel matrix of the plasma sample image under each azimuth angle through image reconstruction, obtaining the amplitude and the phase of a sample scattered light field through the sample information pixel matrix, integrating the amplitude and the phase of the sample scattered light field obtained by the sample information pixel matrix under each azimuth angle to obtain a target pixel matrix, and obtaining an isotropic image according to the target pixel matrix.

The further improved scheme is as follows: obtaining the amplitude and the phase of a sample scattered light field from a sample information pixel matrix through an angular spectrum method, integrating the amplitude and the phase of the sample scattered light field obtained from each sample information pixel matrix in a weighting and averaging mode to obtain a target pixel matrix, and obtaining an isotropic image according to the target pixel matrix.

The further improved scheme is as follows: the calculation formula for obtaining the sample information pixel matrix of the plasma sample image is as follows:

I＝|Eo+Er| ² ＝|Eo| ² +|Er| ² +EoEr′+Eo′Er (1)

wherein Eo is a scattered light field pixel matrix; er is a pixel matrix of the reflected light field; i is an original pixel matrix obtained from a plasma sample image; eo' is a scattered light field phase conjugate wave pixel matrix; er' is a pixel matrix of phase conjugate waves of the reflected light field;

in the formula, E _i Is a matrix of incident light field pixels and E _i The value is approximately Er; i is a plurality of units; k is incident light wave vector k =2 pi/lambda, and lambda is the wavelength of incident light; r is the azimuth scanning radius;

is the azimuth;

E _o ＝(E _i ·O)*PSF (3)

wherein PSF is a point spread function; o is a sample information pixel matrix and is convolution operation; the specific calculation formula of Eo is as follows:

Eo(x，y，θ)＝(α(x，y)·Er(x，y，θ))*E1(x，y)*h(x，y) (4)

wherein X is a coordinate on the X-axis of the pixel and Y is a coordinate on the Y-axis of the pixel; theta is the incident light azimuth angle; o = α (x, y); PSF = E1 (x, y) × h (x, y); e1 is a scattered light field pixel matrix generated by a single scattering source; h (x, y) is the objective lens coherence transfer function;

in the formulae (1) to (5), I, er and E _i Both the PSF and the PSF are known, and a sample information pixel matrix O can be obtained.

The further improved scheme is as follows: the imaging unit is a CMOS image sensor.

In a second aspect, the present invention discloses an imaging system based on multi-azimuth illumination, comprising:

an incident light receiving unit: receiving incident light with different azimuth angles;

an imaging unit: incident light corresponding to different azimuth angles passes through an interference imaging main light path to obtain a plurality of surface plasma interference images in one-to-one correspondence;

an image reconstruction unit: and carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the incident light with different azimuth angles one by one to obtain isotropic images.

The further improved scheme is as follows: the incident light receiving unit is a two-dimensional galvanometer, and the imaging unit is an image sensor.

The further improved scheme is as follows: the incident light is P polarized light.

The further improved scheme is as follows: carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the P polarized light with different azimuth angles one by one to obtain isotropic images, and specifically comprising the following steps:

obtaining a sample information pixel matrix of the plasma sample image under each azimuth angle through image reconstruction, obtaining the amplitude and the phase of a sample scattered light field through the sample information pixel matrix, integrating the amplitude and the phase of the sample scattered light field obtained by the sample information pixel matrix under each azimuth angle to obtain a target pixel matrix, and obtaining an isotropic image according to the target pixel matrix.

The invention has the beneficial effects that:

the method comprises the steps of obtaining a plurality of surface plasma interference images which correspond to P polarized light of different azimuth angles one by utilizing multi-azimuth angle polarized illumination, and carrying out image reconstruction to obtain isotropic images; the reconstructed isotropic image integrates a plurality of azimuth angle information; the invention overcomes the problems of insufficient spatial resolution and anisotropy caused by the adoption of a coherent light inclined illumination imaging mode with a single azimuth angle of the traditional surface plasma microscope, thereby causing image blurring and distortion and failing to image a finer structure.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and it will be apparent to those skilled in the art that other relevant drawings can be obtained from the drawings without inventive effort.

FIG. 1 is a schematic view of an imaging system of the present invention.

FIG. 2 is a graph of azimuthal angle versus polarization direction of incident light.

FIG. 3 is a surface plasmon interference image when the polarization direction of incident light does not follow azimuthal synchronous variation.

Fig. 4 is a surface plasmon interference image when the polarization direction of incident light is changed synchronously with the azimuth angle.

Fig. 5 is an isotropic image obtained using the present invention.

FIG. 6 is a graph of the single azimuth and multi-azimuth reconstruction results of the present invention.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the invention without inventive step, are within the scope of the invention.

The first embodiment is as follows:

a method of imaging based on multi-azimuth illumination, comprising the steps of:

s100, receiving incident light with different azimuth angles; specifically, P-polarized light is preferred, but not limited to P-polarized light, and the P-polarized light with different azimuth angles is formed by the following steps:

the parallel laser is converted into P polarized light through the polarization unit, the azimuth angle of the P polarized light is changed through the continuous rotation of the azimuth angle adjusting unit, and the P polarized light with different azimuth angles is obtained through the polarization adjusting unit.

The parallel light can be obtained by emitting incident light by a laser, and the incident light emitted by the laser is shaped into the parallel light through a collimating lens;

the half-wave plate adjusts the light of the P polarized light incident to the two-dimensional galvanometer through rotation, and the light is the P polarized light; the two-dimensional galvanometer scans the P polarized light through rotation, so that the P polarized light is emitted from different azimuth angles.

S200, the P polarized light with different azimuth angles passes through an interference imaging main light path to obtain a plurality of surface plasma interference images corresponding to the P polarized light with different azimuth angles one by one; as shown in fig. 3 and fig. 4, a specific scheme is as follows:

the interference imaging main optical path comprises an objective lens, an imaging chip for placing a sample and an imaging unit;

the objective lens receives P polarized light with different azimuth angles, and the P polarized light irradiates to an imaging chip with a sample through the objective lens according to a set angle so as to excite the metal interface plasma of the imaging chip to generate surface plasma resonance, and the scattered light of the sample and the reflected light of the metal interface are coupled in a reverse direction and emitted out to be collected by the objective lens;

and the imaging unit is used for receiving the scattered light of the sample and the reflected light of the metal interface and carrying out interference imaging to obtain a surface plasma interference image.

Specifically, P polarized light irradiates an imaging chip with a sample through an objective lens according to a set angle (the imaging chip is generally composed of structures with a plasma resonance phenomenon such as silicon dioxide and gold plates, and the like, and belongs to the prior art), so as to excite metal interface plasma of the imaging chip to generate surface plasma resonance and generate surface plasma waves, after the surface plasma waves are scattered by the sample, part of scattered light is reversely coupled and emitted through the imaging chip, and is collected by the objective lens together with reflected light and enters an imaging unit (such as a CMOS (complementary metal oxide semiconductor) sensor, a CCD (charge coupled device) image sensor or an EMCCD (electron-multiplying charge coupled device) image to form a surface plasma interference image; as shown in fig. 5.

The number of the different azimuth angles of the P polarized light is larger, the number of the surface plasma interference images is larger, such as 6, 12, 20, and the like, and the larger the number is, the higher the accuracy of the obtained isotropic image is.

S300, carrying out image reconstruction on a plurality of surface plasma interference images corresponding to the P polarized light with different azimuth angles one by one to obtain isotropic images.

The interference imaging main optical path comprises an objective lens and an imaging chip for placing a sample; in the embodiment, the main interference imaging light path is built in an objective lens mode, and can be replaced by a prism mode;

the objective lens receives P polarized light with different azimuth angles, and the P polarized light irradiates to an imaging chip with a sample through the objective lens according to a set angle so as to excite the metal interface plasma of the imaging chip to generate surface plasma resonance, and the scattered light of the sample and the reflected light of the metal interface are coupled in a reverse direction and emitted out to be collected by the objective lens;

and (3) collecting sample scattered light and reflected light of a metal interface by the objective lens, and obtaining a surface plasma interference image through interference imaging.

Carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the P polarized light with different azimuth angles one by one to obtain isotropic images, and specifically comprising the following steps:

obtaining a sample information pixel matrix of the plasma sample image under each azimuth angle through image reconstruction, obtaining the amplitude and the phase of a sample scattered light field through the sample information pixel matrix, integrating the amplitude and the phase of the sample scattered light field obtained by the sample information pixel matrix under each azimuth angle to obtain a target pixel matrix, and obtaining an isotropic image according to the target pixel matrix. The CMOS image sensor has the function of acquiring a sample information pixel matrix through a plasma sample image.

Obtaining the amplitude and the phase of a sample scattered light field from a sample information pixel matrix through algorithms such as an angular spectrum method, integrating the amplitude and the phase of the sample scattered light field obtained by each sample information pixel matrix in a weighting and averaging mode to obtain a target pixel matrix, and obtaining an isotropic image according to the target pixel matrix.

The calculation formula for obtaining the sample information pixel matrix of the plasma sample image is as follows:

I＝|Eo+Er| ² ＝|Eo| ² +|Er| ² +EoEr′+Eo′Er (1)

after multiplying two sides by Er, the numerical value | Eo ¬ with less influence is saved ² Er and Er ² Er, given formula (2) and calculated according to formula (2):

I·Er＝|Er| ² Eo+Er ² Eo′ (2)

in the formula, eo is a scattered light field pixel matrix, and Er is a reflected light field pixel matrix; i is an original pixel matrix obtained from a plasma sample image; eo' is a scattered light field phase conjugate wave pixel matrix; er' is a pixel matrix of phase conjugate waves of the reflected light field;

in the formula, E _i Is a matrix of incident light field pixels and E _i Er is approximately distributed, and in the calculation process, the calculation is carried out according to E _i = Er calculation; i is a plurality; k is incident light wave vector k =2 pi/lambda, and lambda is the wavelength of incident light; r is the azimuth scanning radius;

is the azimuth;

E _o ＝(E _i ·O)*PSF (4)

in the formula, the PSF is a point spread function (system transfer function); o is a sample scattering pixel matrix and is convolution operation; the specific calculation formula of Eo is as follows:

Eo(x，y，θ)＝(α(x，y)·Er(x，y，θ))*E1(x，y)*h(x，y) (5)

wherein X is a coordinate on an X-axis of the pixel and Y is a coordinate on a Y-axis of the pixel; theta is the incident light azimuth angle; o = α (x, y); PSF = E1 (x, y) × h (x, y); e1 is a scattered light field pixel matrix generated by a single scattering source; h (x, y) is the objective lens coherence transfer function;

in the formulae (1) to (5), I, er and E _i Both PSFs are known, and a sample information pixel matrix O can be obtained.

Example two:

the embodiment provides an imaging system based on multi-azimuth illumination, which comprises:

an incident light receiving unit: receiving incident light with different azimuth angles; the incident light is preferably P-polarized light;

an imaging unit: incident light corresponding to different azimuth angles passes through an interference imaging main light path to obtain a plurality of surface plasma interference images in one-to-one correspondence;

an image reconstruction unit: and carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the incident light with different azimuth angles one by one to obtain isotropic images.

The incident light receiving unit is a two-dimensional galvanometer or an electric displacement table and the like; the imaging unit is an image sensor, for example: a CMOS sensor, a CCD image sensor, or an EMCCD image sensor.

The following embodiment will be further described with reference to specific practical cases:

referring to fig. 1, an imaging system includes:

a laser for emitting incident light;

the collimating lens is used for shaping incident light emitted by the laser into parallel light;

a polarizing plate for converting the parallel light passing through the collimating lens into polarized light;

the half-wave plate adjusts the polarization direction of the incident polarized light through rotation, so that the polarized light incident to the two-dimensional galvanometer is P polarized light;

the half-wave plate is composed of birefringent crystals, refractive indexes of birefringent materials at two orthogonal main axes of fast and slow axes are different, so that light polarized along the fast axis and the slow axis of incident light has different propagation speeds, and when the light passes through the wave plate, a phase difference is generated between two orthogonal polarization components due to a speed difference, which can be described as follows:

wherein n is ₁ Is the slow axis index, n ₂ Is the orthogonal fast axis index, d is the plate thickness, and λ is the signal wavelength. Therefore, the half-wave plate with specific wavelength corresponds to the phase difference of 1/2 wavelength (pi), and when the incident linearly polarized light is incident on the half-wave plate and is not overlapped with the fast axis or the slow axis, the emergent light still has linear polarizationHowever, the incident light is rotated, and the rotation angle of the emergent light is twice of the included angle between the incident light and the fast axis (slow axis) (determined by the property of the half-wave plate), so that the incident linear polarization can be realized by mounting the half-wave plate on the rotary mounting seat.

The two-dimensional galvanometer scans the P polarized light through rotation to enable the P polarized light to be emitted from different azimuth angles;

the telephoto lens is used for receiving the P polarized light emitted by the two-dimensional galvanometer and converging the P polarized light;

the beam splitter is used for receiving the P polarized light converged by the scanning lens and reflecting the converged P polarized light to a rear focal plane of the objective lens;

the objective lens is used for receiving the P polarized light reflected by the beam splitter and irradiating the P polarized light to an imaging chip with a sample through the objective lens according to a set angle so as to excite the metal interface plasma of the imaging chip to generate surface plasma resonance, and the scattered light of the sample and the reflected light of the metal interface are reversely coupled and emitted out to be collected by the objective lens;

the image sensor is used for receiving scattered light of the sample and reflected light of a metal interface and carrying out interference imaging to obtain a surface plasma interference image; carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the P polarized light with different azimuth angles one by one to obtain an isotropic graph; the image sensor can adopt a CMOS sensor, a CCD image sensor or an EMCCD image sensor; the image sensor can also be provided with a magnifying lens group for magnifying the image.

On the basis of the above scheme, the imaging system further includes: and the control unit is used for controlling the half-wave plate and the two-dimensional galvanometer to rotate according to a set rotating speed, wherein the rotating speed of the two-dimensional galvanometer is 2 times of that of the half-wave plate, for example: the rotating speed of the half-wave plate is 10Hz/s, and the rotating speed of the two-dimensional galvanometer is 20Hz/s; the rotating speeds of the two-dimensional galvanometer and the half-wave plate can be set according to actual requirements. The rotation speed of the two-dimensional galvanometer is controlled to be in synchronous rotation at a constant rotation speed ratio which is 2 times of the rotation speed of the half-wave plate, so that

In the embodiment, the objective lens receives P polarized light with different azimuth angles, and irradiates to an imaging chip with a sample through the objective lens according to a set angle so as to excite the metal interface plasma of the imaging chip to generate surface plasma resonance, and the scattered light of the sample and the reflected light of the metal interface are coupled back and emitted out to be collected by the objective lens; the image sensor is used for collecting scattered light of the sample and reflected light of a metal interface by the objective lens, and imaging to obtain a surface plasma interference image, as shown in fig. 4.

Carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the P polarized light with different azimuth angles one by one to obtain isotropic images, and specifically comprising the following steps: obtaining a sample information pixel matrix of the plasma sample image under each azimuth angle through image reconstruction, obtaining the amplitude and the phase of a sample scattered light field through the sample information pixel matrix, integrating the amplitude and the phase of the sample scattered light field obtained by the sample information pixel matrix under each azimuth angle to obtain a target pixel matrix, and obtaining an isotropic image according to the target pixel matrix. Specifically, the amplitude and the phase of the sample scattered light field are obtained from the sample information pixel matrix through an algorithm such as an angular spectrum method, the amplitude and the phase of the sample scattered light field obtained from each sample information pixel matrix are integrated in a weighting and averaging manner, a target pixel matrix is obtained, an isotropic image is obtained according to the target pixel matrix, and the obtained isotropic image is shown in fig. 5.

Referring to fig. 6, a further comparison of the prior art single azimuth illumination and the multiple azimuth illumination of the present invention is illustrated by the image intensity signal profile: respectively cutting a section of one-dimensional brightness pixel matrix in the horizontal direction and the vertical direction of the particles; the evaluation index is a half-peak width, which is used for evaluating the optical resolution, and a smaller value represents a higher resolution. In fig. 6, the left side is a single azimuthal image intensity signal curve, and the right side is a plurality of azimuthal image intensity signal curves of the present embodiment; it can be seen that in a single azimuth angle, the half-peak width in the vertical direction ≈ 11 × 35 ≈ 385nm, and the half-peak width in the horizontal direction ≈ 64 × 35=2.3um; in this example, the vertical half-peak width ≈ 5 × 35=175nm, and the horizontal half-peak width ≈ 6 × 35=215nm. Therefore, it can be seen that the half-peak width in both the vertical direction and the horizontal direction in the embodiment is lower than that in the technical scheme of a single azimuth angle, and the image definition is higher; in addition, in the embodiment, the half peak widths in the vertical direction and the horizontal direction are relatively close; the difference between the half-peak widths in the vertical direction and the horizontal direction of the existing single azimuth angle is large, the difference is one order of magnitude, and the image distortion is serious.

The surface plasmon resonance requires excitation of incident P-polarized light, so that the polarization direction of the incident light can be adjusted to P-polarized light under a single azimuth angle incident condition, but when the incident light circularly rotates on the back focal plane of the objective lens, the P-polarized component is periodically attenuated, and thus the intensity of the P-polarized light is inconsistent due to the change of the azimuth angle. As shown in fig. 2, which is a diagram of the distribution relationship between the azimuth angle and the intensity of P-polarized light, the diagram (a) is an abstracted optical path when the incident light is P-polarized light, and shows the light beams and the corresponding incident planes when the incident light is at two different azimuth angles, and according to the SPR generation condition and the definition of P-polarized light, when the polarization direction of the incident linearly-polarized light is parallel to the incident plane, it is P-polarized light, and when the polarization direction of the incident light is perpendicular to the incident plane, it is S-polarized light, and when the azimuth angle of the incident light is 0 ° (incident plane 1), it is the initial state, and when the incident plane corresponding to the incident light is the plane of the triangle of the incident plane 1 in the diagram (a), it corresponds to the incident plane 1 line in the projection diagram in the diagram (b), and the double-arrow solid line represents the projection polarization direction of the incident light, and when the incident light is P-polarized light.

When incident light rotates azimuthally

When the polarization direction of the incident light is changed, the plane of the incident light becomes the plane of the plane 2 of the incident light in the graph (a) and the plane where the plane is located, and corresponds to the solid line of the plane 2 in the projection of the graph (b), and because the polarization direction of the incident light is not changed, a certain included angle exists between the polarization direction and the plane of incidence, which is obvious from the solid line of the plane 2 in the graph (b), the P-polarization component can be attenuated under the condition that the polarization direction of the incident light is not changed, and the attenuation depends on the size of the azimuth angle. When the azimuth angle is as shown in (b)

At 90 ° and 270 ° (incidence plane 3), the P-polarized component is 0, and cannot be obtainedSurface plasmon resonance is generated, so that the acquired images have different azimuthal signal intensities.

If the intensity of the P-polarized light is kept consistent when the azimuth angle is changed, the most direct way is to rotate the polarization direction of the incident light to ensure that the P-polarized light is used at each azimuth angle. As shown in (c), when the azimuth angle of the incident light is rotated, the polarization direction of the incident light is changed, and the P-polarized light is not attenuated due to the rotation of the azimuth angle, as shown in (d), the incident light can be ensured to be the complete P-polarized light at any azimuth angle, so as to obtain the intensity signal images with different azimuth angles and the like, and prepare for super-resolution image reconstruction.

When the incident light is rotated in azimuth and its polarization direction is changed, which ensures that the incident light is P-polarized light, as shown in fig. 4, the reconstruction result shows that the sample image shows anisotropy (where the sample is the parabolic portion in the figure) under different azimuth angles (Angle).

When the polarization direction of the incident light does not change along with the rotation of the azimuth angle of the incident light, that is, the polarization direction of the incident light does not change along with the synchronous change of the azimuth angle, the incident light cannot be guaranteed to be P-polarized light, and as shown in fig. 3, the reconstruction result shows that the experimental image only has signals at certain angles, namely signals in the wire frame.

In order to ensure synchronous control of the incidence azimuth angle and polarization at a set rotation speed ratio, the following scheme is adopted in the embodiment:

(1) The control scheme of the incident angle and the azimuth angle is selected, and the control scheme optionally comprises the steps of moving a laser light source by using an electric three-dimensional displacement table or deflecting incident light by using a galvanometer system to realize angle scanning. The present embodiment preferably uses a galvanometer system to achieve azimuthal scanning, because this method can achieve large-angle high-speed scanning, and the scanning precision and scanning speed are better than those of a motorized displacement table, and the galvanometer is a GVS002 two-dimensional scanning galvanometer from Thorlabs corporation.

(2) An electric rotating platform for controlling the rotation of a half-wave plate, the requirements of the rotating platform mainly comprise: (1) the rotation angle is 0-360 degrees; (2) the rotating speed can be selected according to requirements, and the rotating speed is required to be 0-1200rpm (0-20 Hz); (3) because the rotating table can bring certain mechanical noise after rotating at high speed, in order to prevent the rotating table from influencing the light path and imaging, the end surface and the radial surface of the rotating table are required to jump less than 0.02mm (when 3000 rpm); (4) the maximum torque requirement can be a fixed one inch half-wave plate at maximum speed; (5) the synchronous triggering of the two-dimensional scanning galvanometer and the rotating platform can be realized by external voltage; (6) the rotation precision is less than 0.1 degree; the electric rotating platform is matched with an SV-X3E series motor produced by the domestic Hechuan company to control the half-wave plate to stably rotate at a high speed.

(3) The signal control of the electric rotating platform and the galvanometer system adopts a PCI-6154 data acquisition card purchased from National Instruments company, and can realize the high-speed laser circular scanning with the scanning period of 50ms and the number of scanning points of 0-360 points per circle of the galvanometer.

The invention is not limited to the above alternative embodiments, and any other various forms of products can be obtained by anyone in the light of the present invention, but any changes in shape or structure thereof, which fall within the scope of the present invention as defined in the claims, fall within the scope of the present invention.

Claims (10)

1. An imaging method based on multi-azimuth illumination, comprising the steps of:

s100, receiving incident light with different azimuth angles;

s200, obtaining a plurality of surface plasma interference images in one-to-one correspondence by incident light corresponding to different azimuth angles through an interference imaging main light path;

s300, carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the incident light with different azimuth angles one by one to obtain isotropic images.

2. The method of claim 1, wherein the incident light is P-polarized light.

3. The imaging method based on multi-azimuth illumination of claim 2, wherein in step S100, the P-polarized light with different azimuths is formed by:

the parallel laser is converted into P polarized light through the polarization unit, and the polarization direction of the P polarized light is changed through continuous rotation of the polarization unit, so that the P polarized light with a plurality of different azimuth angles is obtained.

4. The imaging method based on multi-azimuth illumination according to claim 1, wherein the interference imaging main light path comprises an objective lens, an imaging chip for placing a sample and an imaging unit;

the objective lens receives incident light with different azimuth angles, and the incident light irradiates an imaging chip with a sample through the objective lens according to a set angle so as to excite the metal interface plasma of the imaging chip to generate surface plasma resonance, and the scattered light of the sample and the reflected light of the metal interface are coupled back and emitted out to be collected by the objective lens;

and the sample scattered light collected by the objective lens and the reflected light of the metal interface are subjected to interference imaging to obtain a surface plasma interference image.

5. The imaging method according to claim 1, wherein in step S300, the image reconstruction is performed on a plurality of surface plasmon interference images corresponding to incident light with different azimuths in a one-to-one manner, so as to obtain an isotropic image, and specifically includes:

obtaining a sample information pixel matrix of the plasma sample image under each azimuth angle through image reconstruction, obtaining the amplitude and the phase of a sample scattered light field through the sample information pixel matrix, integrating the amplitude and the phase of the sample scattered light field obtained by the sample information pixel matrix under each azimuth angle to obtain a target pixel matrix, and obtaining an isotropic image according to the target pixel matrix.

6. The imaging method based on multi-azimuth illumination according to claim 5, wherein the amplitude and phase of the sample scattered light field are obtained from the sample information pixel matrix by an angular spectrum method, and the amplitude and phase of the sample scattered light field obtained from each sample information pixel matrix are integrated by means of weighting and averaging to obtain the target pixel matrix and obtain the isotropic image according to the target pixel matrix.

7. The multi-azimuth illumination-based imaging method according to claim 5, wherein the calculation formula for the sample information pixel matrix acquisition of the plasma sample image is as follows:

I＝|Eo+Er| ² ＝|Eo| ² +|Er| ² +EoEr′+Eo′Er (1)

wherein Eo is a scattered light field pixel matrix; er is a pixel matrix of the reflected light field; i is an original pixel matrix obtained from a plasma sample image; eo' is a scattered light field phase conjugate wave pixel matrix; er' is a pixel matrix of phase conjugate waves of the reflected light field;

in the formula, E _i Is a matrix of incident light field pixels and E _i The value is approximately Er; i is a plurality of units; k is incident light wave vector k =2 pi/lambda, and lambda is the wavelength of incident light; r is the azimuth scanning radius;

is the azimuth;

E _o ＝(E _i ·O)*PSF (3)

wherein PSF is a point spread function; o is a sample information pixel matrix and is convolution operation; the specific calculation formula of Eo is as follows:

Eo(x，y，θ)＝(α(x，y)·Er(x，y，θ))*E1(x，y)*h(x，y) (4)

wherein X is a coordinate on an X-axis of the pixel and Y is a coordinate on a Y-axis of the pixel; theta is the incident light azimuth angle; o = α (x, y); PSF = E1 (x, y) × h (x, y); e1 is a scattered light field pixel matrix generated by a single scattering source; h (x, y) is the objective lens coherence transfer function;

in the formulae (1) to (5),I、Er、E _i both PSFs are known, and a sample information pixel matrix O can be obtained.

8. An imaging system based on multi-azimuth illumination, comprising:

an incident light receiving unit: receiving incident light with different azimuth angles;

an imaging unit: incident light corresponding to different azimuth angles passes through an interference imaging main light path to obtain a plurality of surface plasma interference images in one-to-one correspondence;

an image reconstruction unit: and carrying out image reconstruction on a plurality of surface plasma interference images which correspond to the incident light with different azimuth angles one by one to obtain isotropic images.

9. The multi-azimuth illumination-based imaging system according to claim 8, wherein the incident light receiving unit is a two-dimensional galvanometer and the imaging unit is an image sensor.

10. The multi-azimuth illumination-based imaging system according to claim 8, wherein the incident light is P-polarized light.

Images