WO2020037837A1 - Three-dimensional imaging apparatus based on k space transformation and imaging method thereof - Google Patents

Abstract

A three-dimensional imaging method based on K space transformation, the method using sheet-shaped light to illuminate a sample along the direction of an optical axis, and using an identical sheet-shaped light source to interfere with the illuminating light; recording an interferogram and acquiring therefrom complex amplitude information (comprising the amplitude and phase) of the illuminated sample in the focal plane; spatial frequency spectrum information of the sample can be acquired by means of discrete Fourier transformation; using a projection method to calculate spatial frequency spectrum information perpendicular to the plane of the sample; by means of discrete Fourier inverse transformation, acquiring strength information perpendicular to the plane of the sample; and, by means of scanning, acquiring final three-dimensional structure information of the sample. The method has a high acquisition rate and high resolution, particularly for the acquisition of axial information, and only needs to perform acquisition once to implement imaging.

Description

Three-dimensional imaging device and imaging method based on K-space transformation Technical field

The invention relates to the field of three-dimensional imaging, in particular to a three-dimensional imaging device based on K-space transformation and an imaging method thereof.

Background technique

Three-dimensional imaging technology has developed rapidly due to its wide reference. This technology has a great role in the observation of biological samples and tumor diagnosis. There are many methods used in the field of three-dimensional imaging, such as structured light illumination technology, confocal scanning, coherence tomography, flake illumination microscopy, and coherence tomography. These technologies are able to reflect the internal structure of the sample, including information such as the reflectance of the sample and the concentration of the luminescent material. Structured light three-dimensional imaging technology uses a carrier frequency stripe to illuminate the object, records the deformed stripes, and then digitally demodulates the reconstructed three-dimensional image from the deformed fringe map obtained to reconstruct the three-dimensional image of the measured object. The shadow effect of the focal part. The most widely used 3D imaging technology is confocal scanning technology. This technology uses pinholes to block the passage of light from the out-of-focus portion, thereby eliminating the effects of shadows from the out-of-focus sample. However, because it needs to use point-by-point scanning for imaging, it takes a lot of time to collect the data portion. Optical coherence tomography can use gratings and two-dimensional scanning galvanometers to achieve high lateral and vertical resolution. The flake light illumination microscopy technology uses a flake light source to illuminate the sample, and at the same time collects reflected light in a direction perpendicular to the optical path. Since the illumination light is a flake light, the collected reflected light is the axial distribution of the sample. Since the lighting system and the acquisition system are not co-axial systems, this technology is difficult to implement. The method proposed by this patent has high imaging rate, spatial resolution, simple structure, and easy construction and assembly.

Summary of the Invention

The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art, and provide a three-dimensional imaging method with high imaging speed, high resolution, simple structure, and easy construction and assembly.

To solve the above problems, the technical solution of the present invention is as follows:

A three-dimensional imaging device based on K-space transformation, which is characterized by comprising a laser, a lens, a first beam splitting prism, a first cylindrical lens, a spot detector, a computer, a second beam splitting prism, a microscope objective lens, and a place for a sample to be measured. One-dimensional motorized stage, holder, microscope objective group, first reflecting mirror, second cylindrical lens, and second reflecting mirror.

The positional relationship of the above components is as follows:

The laser light emitted by the laser (1) passes through the lens (2) and becomes a parallel beam. The beam is transmitted and reflected by the first beam splitting prism (3), that is, a detection beam and a reference beam. The detection beam passes through the first A cylindrical lens (4) is focused into a sheet-shaped illumination light, and is condensed into a thinner sheet-shaped sheet-shaped illumination light by a second spectroscopic prism (7) and a microscope objective lens (8) in order, and irradiates the sample to be measured. After the reflection of the sample is measured, the original path is returned, transmitted through the micro objective lens (8), and then incident on the second beam splitting prism (7);

After the reference beam is reflected by the second reflector (14), a sheet-shaped reference light is formed through the second cylindrical lens (13), and after being reflected by the first reflector (12), it passes through the microscope objective lens group (11) in order. ) And the second spectroscopic prism (7) are transmitted, and together with the detection beam reflected by the second spectroscopic prism (7), they are incident on the spot detector (5), and the computer (6) and the spot detector are respectively (5) Connected to the one-dimensional motorized stage (9).

The method for performing three-dimensional imaging of a sample to be measured by using the three-dimensional imaging device based on K-space transformation is characterized in that the method includes the following steps:

① Take the laser emitted by the laser as the optical axis, fix the sample to be tested on the one-dimensional motorized stage, and control the one-dimensional motorized stage into the optical path, so that the sample to be measured is perpendicular to the incident direction of the detection beam, and at the same time, ensure that Each optical element is perpendicular to the detection beam and the center is kept on the optical axis;

② measurement sample to be tested from a second dichroic prism (7) to L _1, a second dichroic prism (7) to the distance (5) of the target surface of the probe light spot L _2, and a second dichroic prism (7) has a width D ;

③ Block the reference light path, keep the detection light path, and record the first scattered light spot with a light spot detector;

④ Block the detection light path, keep the reference light path, and record the second scattered light spot with a light spot detector;

⑤ Keep the detection light path and reference light path, and record the third scattered light spot with a spot detector;

⑥ The computer (6) controls the movement of the one-dimensional motorized stage (9), so that the sample to be measured is moved in a direction perpendicular to the optical axis according to a preset moving step l, and each time the movement is performed, the light spot detector collects and repeats the steps ③ , ④, ⑤ until moving n times, collect 3n scattered light spots;

The intensity of the light spot recorded by the radon spot detector is input into the computer, and the computer performs three-dimensional imaging of the sample to be measured.

The spot intensity recorded by the spot detector is input to a computer, and the computer uses the spot data to perform three-dimensional imaging of the sample to be measured.

A computer is used to calculate the 3n scattered light version recorded by the spot detector. The calculation process is as follows:

Step 7.1, let n = 1;

Step 7.2: Read in the three scattered light spots recorded by the n-th movement of the one-dimensional motorized stage;

Step 7.3: Use the sum of the 3rd scattered light spot pattern of the nth time and the sum of the 1st and 2nd scattered light spot patterns of the nth time to make a difference;

Step 7.4: Perform a discrete Fourier transform on the image obtained in step 7.3, and then intercept the first-level spectrum and translate it to the center of the image;

Step 7.5: Perform inverse discrete Fourier transform on the image obtained in step 7.4, and then use the Fresnel propagation formula to propagate to the center plane of the sample, and the propagation distance is: D + L ₁ + L ₂ ;

Step 7.6: Perform a discrete Fourier transform on the image obtained in step 7.5;

Step 7.7, use the formula

Obtain the corresponding position of the wavefront on the optical axis, where p is the axial position, m is the lateral position, n is the longitudinal position, λ is the laser wavelength, Δk _x is the lateral spatial frequency, Δk _y is the longitudinal spatial frequency, and Δk _z Axial space frequency

Step 7.8: Move the corresponding amplitude and phase of the data (m, n) to (m, p), thereby projecting the wavefront to a plane parallel to the optical axis;

Step 7.9: Perform a discrete inverse Fourier transform on the result obtained in step 7.8;

Step 7.10, let n = n + 1, repeat steps 7.2 to 7.9 until the motorized stage moves n times, and the finally obtained three-dimensional data set is the three-dimensional information of the sample to be measured.

Compared with the prior art, the technical effects of the present invention are:

(1) This method does not require scanning in order to achieve axial imaging, and a depth map of the sample to be measured can be obtained by one acquisition;

(2) The method satisfies coaxial imaging, so the optical path is simple and the equipment stability is high;

(3) This method can eliminate mutual crosstalk between different levels and shield the projection of the blurred position.

(4) The cost is lower than the existing methods such as optical coherence tomography, which has a very broad market prospect in the field of optical component detection.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without labor.

FIG. 1 is a schematic diagram of an apparatus for a three-dimensional imaging method based on K-space transformation according to the present invention.

In the picture: 1-laser, 2-lens, 3-first beamsplitter prism, 4-first cylinder lens, 5-spot detector, 6-computer, 7-spectroscopy prism, 8-microscope objective lens, 9-waiting One-dimensional motorized stage for sample placement, 10-holder, 11-microscope objective group, 12-first reflector, 13-second cylindrical lens, 14-second reflector, sample holder to be tested The straight line distance from 9 to the second beam splitting prism 7 is L ₁ , the straight line distance from the second beam splitting prism 7 to the target surface of the light spot detector is L ₂ , and the width of the second beam splitting prism 7 is D.

detailed description

The present invention is further described below with reference to the embodiments and the accompanying drawings, but the scope of protection of the present invention should not be limited by this embodiment.

Please participate in FIG. 1 first. FIG. 1 is a schematic diagram of a three-dimensional imaging method based on K-space transformation. As shown in the figure, a laser with a wavelength of 632.8 nm emitted by laser 1 passes through lens 2 to become a parallel light with a flat phase, and then passes through the light. The beam splitting prism 3 with a ratio of 1: 1 splits the beam to produce two parallel beams of equal intensity, which are a detection beam and a reference beam, respectively. The detection beam is focused by the cylindrical lens 4 into a sheet-shaped illumination light and passes through a microscope objective lens. 5. Converge into thinner sheet-shaped illumination light and illuminate the sample holder 10 to be tested; the sample holder to be tested is controlled by a one-dimensional motorized stage 9, and the light in the reference optical path is split by a beam splitter and passed through After being reflected by the reflecting mirror 14, the sheet-shaped reference light is formed through the cylindrical lens 13, and after being reflected by the reflecting mirror 12, the reflected light irradiated on the sample holder 10 to be measured by the micro objective lens group 11 and the detection light passes through the beam splitting prism. 7. Record by the spot detector 5 and transfer the recorded data to the computer 6.

The laser (1) emits a laser with a wavelength of 632.8 nm and passes through the lens (2) to become a parallel beam. The beam is split into a transmitted beam and a reflected beam by a first beam splitting prism (3) with a beam splitting ratio of 1: 1, that is, detection. Light beam and reference light beam, the detection beam is focused by the first cylindrical lens (4) into sheet-like illumination light, and then passes through a second beam splitting prism (7) and a microscope objective lens (8) in order of 1: 1. The thinner sheet-shaped illumination light condensed into a thin sheet is irradiated on the sample to be measured, and after being reflected by the sample to be measured, it returns to the original path, passes through the microscope objective lens (8), and enters the second beam splitting prism (7);

After the reference beam is reflected by the second reflector (14), a sheet-shaped reference light is formed through the second cylindrical lens (13), and after being reflected by the first reflector (12), it passes through the microscope objective lens group (11) in order. ) And the second spectroscopic prism (7) are transmitted, and together with the detection beam reflected by the second spectroscopic prism (7), they are incident on the spot detector (5), and the computer (6) and the spot detector are respectively (5) Connected to the one-dimensional motorized stage (9).

The focal length of the first cylindrical lens 4 and the second cylindrical lens 13 is 40 mm, the linear distance between the cylindrical lens 4 and the microscope objective lens 8 is 48.83 mm, the microscope objective lens 8 is a 10x objective lens, and the microscope objective lens 8 is clamped to the sample to be measured. The linear distance of the detector 10 is 0.97mm, the resolution of the light spot detector 5 is 2048 pixels × 2048 pixels, and the minimum unit is 5.5 μm. Each time the one-dimensional motorized stage moves, the light spot detector records 3 scattered light spots, which are respectively blocked. Reference light, keep the detection light, block the detection light, keep the reference light, and at the same time keep the scattergram recorded in the three cases of detection light and reference light. The one-dimensional motorized stage was moved 200 times in total, and the accuracy of each movement was 5.5 μm, which were input into the computer for calculation.

To use this device for three-dimensional imaging, the steps are as follows:

① Take the laser emitted by the laser as the optical axis, fix the sample to be tested on the one-dimensional motorized stage, and control the one-dimensional motorized stage into the optical path, so that the sample to be measured is perpendicular to the incident direction of the detection beam, and at the same time, ensure that Each optical element is perpendicular to the detection beam and the center is kept on the optical axis;

② measurement sample to be tested from a second dichroic prism (7) to L _1, a second dichroic prism (7) to the distance (5) of the target surface of the probe light spot L _2, and a second dichroic prism (7) has a width D ;

③ Block the reference light path, keep the detection light path, and record the first scattered light spot with a light spot detector;

④ Block the detection light path, keep the reference light path, and record the second scattered light spot with a light spot detector;

⑤ Keep the detection light path and reference light path, and record the third scattered light spot with a spot detector;

⑥ The computer (6) controls the movement of the one-dimensional motorized stage (9), so that the sample to be measured is moved in a direction perpendicular to the optical axis according to a preset moving step l, and each time the movement is performed, the light spot detector collects and repeats the steps ③ , ④, ⑤ until moving n times, collect 3n scattered light spots;

The intensity of the light spot recorded by the radon spot detector is input into the computer, and the computer performs three-dimensional imaging of the sample to be measured.

The spot intensity recorded by the spot detector is input to a computer, and the computer uses the spot data to perform three-dimensional imaging of the sample to be measured.

A computer is used to calculate the 3n scattered light version recorded by the spot detector. The calculation process is as follows:

Step 7.1, let n = 1;

Step 7.2: Read in the three scattered light spots recorded by the n-th movement of the one-dimensional motorized stage;

Step 7.3: Use the sum of the 3rd scattered light spot pattern of the nth time and the sum of the 1st and 2nd scattered light spot patterns of the nth time to make a difference;

Step 7.4: Perform a discrete Fourier transform on the image obtained in step 7.3, and then intercept the first-level spectrum and translate it to the center of the image;

Step 7.5: Perform inverse discrete Fourier transform on the image obtained in step 7.4, and then use the Fresnel propagation formula to propagate to the center plane of the sample, and the propagation distance is: D + L ₁ + L ₂ ;

Step 7.6: Perform a discrete Fourier transform on the image obtained in step 7.5;

Step 7.7, use the formula

Obtain the corresponding position of the wavefront on the optical axis, where p is the axial position, m is the lateral position, n is the longitudinal position, λ is the laser wavelength, Δk _x is the lateral spatial frequency, Δk _y is the longitudinal spatial frequency, and Δk _z Axial space frequency

Step 7.8: Move the corresponding amplitude and phase of the data (m, n) to (m, p), thereby projecting the wavefront to a plane parallel to the optical axis;

Step 7.9: Perform a discrete inverse Fourier transform on the result obtained in step 7.8;

Step 7.10, let n = n + 1, repeat steps 7.2 to 7.9 until the motorized stage moves n times, and the finally obtained three-dimensional data set is the three-dimensional information of the sample to be measured.

The experimental results show that the device of the present invention successfully realizes three-dimensional imaging of the sample. The device uses scanning to record 3n scattered light spots, and the computer calculates and displays the three-dimensional structural characteristics of the sample. This method is not limited to the size of the light spot detector. Less affected by the environment, the device has a simple structure, high measurement resolution, and fast imaging speed, which meets the requirements for three-dimensional inspection of optical components.

Claims (6)

1. A three-dimensional imaging device based on K-space transformation, which is characterized by comprising a laser (1), a lens (2), a first beam splitting prism (3), a first cylindrical lens (4), a spot detector (5), and a computer. (6), the second beam splitting prism (7), the micro objective lens (8), the one-dimensional motorized stage (9) for placing the sample to be measured, the holder (10), the micro objective lens group (11), the first A reflecting mirror (12), a second cylindrical lens (13), and a second reflecting mirror (14);

   The positional relationship of the above components is as follows:

   The laser light emitted by the laser (1) passes through the lens (2) and becomes a parallel beam. The beam is transmitted and reflected by the first beam splitting prism (3), that is, a detection beam and a reference beam. The detection beam passes through the first A cylindrical lens (4) is focused into a sheet-shaped illumination light, and is condensed into a thinner sheet-shaped sheet-shaped illumination light by a second spectroscopic prism (7) and a microscope objective lens (8) in order, and irradiates the sample to be measured. After the reflection of the sample is measured, the original path is returned, transmitted through the micro objective lens (8), and then incident on the second beam splitting prism (7);

   After the reference beam is reflected by the second reflector (14), a sheet-shaped reference light is formed through the second cylindrical lens (13), and after being reflected by the first reflector (12), it passes through the microscope objective lens group (11) in order. ) And the second spectroscopic prism (7) are transmitted, and together with the detection beam reflected by the second spectroscopic prism (7), they are incident on the spot detector (5), and the computer (6) and the spot detector are respectively (5) Connected to the one-dimensional motorized stage (9).
2. The three-dimensional imaging device based on K-space transformation according to claim 1, further comprising a holder (10), which is controlled by a one-dimensional motorized stage (9) for fixing Test sample.
3. The method for performing three-dimensional imaging on a sample to be tested by using the three-dimensional imaging device based on K-space transformation according to claim 1 or 2, wherein the method includes the following steps:

   ① Take the laser emitted by the laser as the optical axis, fix the sample to be tested on the one-dimensional motorized stage, and control the one-dimensional motorized stage into the optical path, so that the sample to be measured is perpendicular to the incident direction of the detection beam, and at the same time, ensure that Each optical element is perpendicular to the detection beam and the center is kept on the optical axis;

   ② measurement sample to be tested from a second dichroic prism (7) to L _1, a second dichroic prism (7) to the distance (5) of the target surface of the probe light spot L _2, and a second dichroic prism (7) has a width D ;

   ③ Block the reference light path, keep the detection light path, and record the first scattered light spot with a light spot detector;

   ④ Block the detection light path, keep the reference light path, and record the second scattered light spot with a light spot detector;

   ⑤ Keep the detection light path and reference light path, and record the third scattered light spot with a spot detector;

   ⑥ The computer (6) controls the movement of the one-dimensional motorized stage (9), so that the sample to be measured is moved in a direction perpendicular to the optical axis according to a preset moving step l, and each time the movement is performed, the light spot detector collects and repeats the steps ③ , ④, ⑤ until moving n times, collect 3n scattered light spots;

   The intensity of the light spot recorded by the radon spot detector is input into the computer, and the computer performs three-dimensional imaging of the sample to be measured.
4. The three-dimensional imaging method according to claim 3, wherein in the step (3), a computer performs three-dimensional imaging on the 3n scattered light spots recorded by the light spot detector, and the specific steps are as follows:

   Step 7.1, let n = 1;

   Step 7.2: Read in the three scattered light spots recorded by the n-th movement of the one-dimensional motorized stage;

   Step 7.3: Use the sum of the 3rd scattered light spot pattern of the nth time and the sum of the 1st and 2nd scattered light spot patterns of the nth time to make a difference;

   Step 7.4: Perform a discrete Fourier transform on the image obtained in step 7.3, and then intercept the first-level spectrum and translate it to the center of the image;

   Step 7.5: Perform inverse discrete Fourier transform on the image obtained in step 7.4, and then use the Fresnel propagation formula to propagate to the center plane of the sample, and the propagation distance is: D + L ₁ + L ₂ ;

   Step 7.6: Perform a discrete Fourier transform on the image obtained in step 7.5;

   Step 7.7, use the formula

   

   Obtain the corresponding position of the wavefront on the optical axis, where p is the axial position, m is the lateral position, n is the longitudinal position, λ is the laser wavelength, Δk _x is the lateral spatial frequency, Δk _y is the longitudinal spatial frequency, and Δk _z Axial space frequency

   Step 7.8: Move the corresponding amplitude and phase of the data (m, n) to (m, p), thereby projecting the wavefront to a plane parallel to the optical axis;

   Step 7.9: Perform a discrete inverse Fourier transform on the result obtained in step 7.8;

   Step 7.10, let n = n + 1, repeat steps 7.2 to 7.9 until the motorized stage moves n times, and the finally obtained three-dimensional data set is the three-dimensional information of the sample to be measured.
5. The three-dimensional imaging method according to claim 3 or 4, wherein the preset moving step size l ranges from 1 μm to 10 μm.
6. The three-dimensional imaging method according to claim 3 or 4, wherein the range of the number n of movements of the one-dimensional motorized stage is 300-500 times.

Images