Polarization multiplexing phase shift structured illumination imaging system and imaging method and device thereof

Abstract

The invention discloses a polarization multiplexing phase shift structured illumination imaging system and an imaging method and device thereof.The polarization multiplexing phase shift structured illumination imaging system comprises an illumination unit, an imaging unit and a processor, the illumination unit comprises an area light source and a polarization polarizer, the imaging unit comprises an imaging lens set and a polarization camera, and light emitted by the area light source comprises linear polarization states in multiple directions; the polarization polarizer comprises a plurality of polarization units with polarization angles, the polarization camera comprises a plurality of polarization detection units with polarization detection angles, light emitted by the area light source reaches a target object through the polarization polarizer, and light reflected by the target object reaches the polarization camera for imaging through the imaging lens group. The processor is used for determining the image of the target object according to the shot image of the polarization camera. The embodiment of the invention can shoot the dynamic target object once to realize phase-shift structured illumination imaging, and can be widely applied to the technical field of imaging.

Description

Technical Field

[0001] The present invention relates to the field of imaging technology, and in particular to a polarization multiplexed phase-shift structured illumination imaging system and an imaging method and device thereof. Background Art

[0002] Stripe structured illumination imaging technology has become a widely used computational optical imaging technology, such as stripe structured illumination three-dimensional profilometry, stripe structured illumination microscopy, etc. There are two existing methods for generating stripe structured light, one is to modulate the amplitude of the light wave through a spatial modulator; the other is through the interference of two coherent light waves. Stripe structured illumination optical imaging technology usually illuminates the generated stripe structured light onto the imaged target object, the camera captures the image of the target object with structured illumination, and then uses the captured image to obtain the required target object image through computational reconstruction. Among them, phase-shifted structured illumination imaging technology has relatively high image reconstruction accuracy and noise resistance. However, this technology requires that the target object is illuminated multiple times (at least three times) with structured light of different phase shifts while the state remains unchanged, the camera captures multiple images in sequence, and then uses the multiple images captured by multiple exposures to calculate and reconstruct the required target object image. Obviously, phase-shifted structured illumination imaging technology with multiple exposures is not conducive to the imaging of dynamic target objects. Summary of the invention

[0003] In view of this, in order to solve one of the above problems, an embodiment of the present invention aims to provide a polarization multiplexed phase-shift structured illumination imaging system and an imaging method and device thereof, which can realize phase-shift structured illumination imaging of a dynamic target object with a single exposure and one shot.

[0004] On the one hand, an embodiment of the present invention provides a polarization-multiplexed phase-shift structured illumination imaging system, comprising an illumination unit, an imaging unit and a processor, wherein the illumination unit comprises a surface light source and a polarizing polarizer, the imaging unit comprises an imaging lens group and a polarization camera, the light emitted by the surface light source comprises linear polarization states in multiple directions, the polarizing polarizer comprises a plurality of polarization units with polarization angles, and the polarization units are periodically arranged on a plane in a one-dimensional direction according to the polarization angles from 0 to π, the polarization camera comprises a plurality of analyzer units with analyzer angles, the light emitted by the surface light source passes through the polarizing polarizer to reach a target object, the light transmitted or reflected by the target object passes through the imaging lens group to reach the polarization camera for imaging, and the processor is used to determine an image of the target object according to an image captured by the polarization camera.

[0005] Optionally, the polarizing polarizer comprises any one of a metal wire grid polarizing unit array, a liquid crystal polarizing unit array or a dichroic material polarizing unit array.

[0006] Optionally, the system further comprises an illumination lens group, wherein the illumination lens group is arranged between the polarizing polarizer and the target object.

[0007] Optionally, the illumination lens group includes an illumination tube lens and an illumination microscope objective lens.

[0008] Optionally, the imaging lens group includes an imaging microscope objective and an imaging tube lens.

[0009] Optionally, the surface light source includes an LED array light source, and the polarizing polarizer covers the surface of the LED array light source.

[0010] On the other hand, an embodiment of the present invention provides a polarization multiplexed phase-shift structured illumination imaging method, which is applied to the above-mentioned imaging system, including:

[0011] Single exposure to obtain an image captured by the polarization camera;

[0012] Splitting the captured image according to a plurality of polarization analysis angles to obtain a plurality of polarization sub-images;

[0013] Calculating the polarization sub-image to obtain a plurality of phase-shifted images;

[0014] A phase image or an intensity image of the target object is reconstructed according to the plurality of phase-shifted images.

[0015] Optionally, the phase shift image is calculated using the following formula:

[0016] I k′ (m′,n′)=I0(m′,n′)cos 2 β k′ +I2(m′,n′)sin 2 β k′ +[I1(m′,n′)-I3(m′,n′)]cosβk′sinβ k′

[0017] k'=0、1、2、...、N s -1

[0018] β k′ =π(k′ / N S )

[0019] Among them, I k '(m',n') represents the k'th phase-shifted image, β k' represents the k'th analysis angle, N SRepresents the total number of phase-shifted images of a polarization sub-image. I0(m′,n′), I1(m′,n′), I2(m′,n′), and I3(m′,n′) are polarization sub-images with analysis angles of 0, π / 4, π / 2, and 3π / 4, respectively.

[0020] Optionally, the phase image or intensity image of the target object is reconstructed by the following formula:

[0021]

[0022] in, represents the phase image of the target object after reconstruction, and I(m′,n′) represents the intensity image of the target object after reconstruction.

[0023] On the other hand, an embodiment of the present invention provides a polarization multiplexed phase-shift structured illumination imaging device, comprising:

[0024] at least one processor;

[0025] at least one memory for storing at least one program;

[0026] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0027] The implementation of the embodiment of the present invention includes the following beneficial effects: the present embodiment uses a polarization unit array with multiple polarization angles as a polarizing polarizer to polarize the light beam emitted by the surface light source to form a polarization structured light beam with an uneven spatial distribution of polarization states, and uses the polarization structured light beam to illuminate the target object. The polarization camera takes an image of the polarized light beam passing through the target object with a single exposure, and according to the multiple polarization angles of the polarization camera, a plurality of polarization sub-images with different polarization states are separated from the captured image. These polarization sub-images can be used to obtain multiple phase-shifted fringe images by calculation, that is, multiple phase-shifted fringe images that need to be obtained by multiple exposures by the traditional phase shift method can be obtained by a single exposure; using these phase-shifted fringe images, the required image can be calculated and reconstructed. For example, the traditional 16-step phase-shifted structured illumination imaging technology requires 16 exposures to shoot 16 phase-shifted fringe images, and the imaging time is long, which is not conducive to imaging dynamic target objects. The single-exposure multi-step phase-shifted structured illumination imaging technology of the present invention greatly reduces the imaging time compared to the traditional multi-exposure multi-step phase-shifted structured illumination imaging technology, and can solve the imaging problem of dynamic target objects by the multi-step phase-shifted structured illumination imaging technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of a polarization multiplexed phase-shift structured illumination imaging system provided by an embodiment of the present invention;

[0029] Figure 2 is a schematic structural diagram of a polarizing polarizer provided by an embodiment of the present invention;

[0030] Figure 3 is a schematic structural diagram of another polarization multiplexed phase-shift structured illumination imaging system provided by an embodiment of the present invention;

[0031] Figure 4 is a structural schematic diagram of an illumination lens assembly provided by an embodiment of the present invention;

[0032] Figure 5 is a structural schematic diagram of an imaging lens assembly provided by an embodiment of the present invention;

[0033] Figure 6 It is a schematic flow chart of the steps of an imaging method of a polarization multiplexed phase-shift structured illumination imaging system provided by an embodiment of the present invention;

[0034] Figure 7 is a schematic structural diagram of another polarization multiplexed phase-shift structured illumination imaging system provided by an embodiment of the present invention;

[0035] Figure 8 It is a structural block diagram of an imaging device of a polarization multiplexed phase-shift structured illumination imaging system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0037] like Figure 1 and Figure 3As shown, an embodiment of the present invention provides a polarization multiplexed phase-shift structured illumination imaging system, comprising an illumination unit (1), an imaging unit (2) and a processor (3), wherein the illumination unit (1) comprises a surface light source (11) and a polarizing polarizer (12), the imaging unit (2) comprises an imaging lens group (21) and a polarization camera (22), the light emitted by the surface light source (11) comprises linear polarization states in multiple directions, the polarizing polarizer (12) comprises polarization units with multiple polarization angles, and the polarization units are arranged in a one-dimensional direction according to the size of the polarization angle. The polarization camera (22) is periodically arranged from 0 to π on a plane, the polarization camera (22) comprises a plurality of polarization analysis units with different polarization analysis angles, the light emitted by the surface light source (11) passes through the polarizing polarizer (12) to reach the target object (4), the light transmitted or reflected by the target object (4) passes through the imaging lens group (21) to reach the polarization camera (22) for imaging, the processor (3) is used to determine the image of the target object according to the image captured by the polarization camera, and at the same time, the processor (3) is used to control the surface light source (11) and the polarization camera (22).

[0038] See also Figure 2 , the polarizing polarizer is an array of polarization units arranged on a plane, and all polarization units are arranged periodically according to the size of the polarization angle; it should be noted that the number of polarization angles contained in the polarizing polarizer is determined according to the actual application, and this embodiment does not impose any specific restrictions. The light beam emitted by the surface light source forms a polarized structured light beam after passing through the polarizing polarizer; the polarized structured light beam illuminates the target object, and the polarization camera takes an image of the polarized light beam passing through the target object with a single exposure; from the captured image, multiple polarization sub-images with the same polarization state are separated, and multiple multi-step phase-shifted fringe images are calculated through these polarization sub-images; using these multiple phase-shifted fringe images, the final image required for calculation and reconstruction is reconstructed.

[0039] The surface light source is composed of many point light sources distributed on a surface. The light beam emitted by each point contains linear polarization states in all directions. The polarizing polarizer is a one-dimensional polarization unit array distributed on a plane. The polarization angle of the polarization unit is α(i), where the polarization angle satisfies the following formula:

[0040]

[0041] Among them, α(i) is the angle between the polarization direction of the polarization unit and the x direction, i is the unit number in the x-coordinate direction of the plane, T is the number of units (period) in which the polarization angle gradually changes from 0 to π, and Q is the number of periods; among them, T is a positive integer, Q is zero or a positive integer, and (x, y) is the spatial rectangular coordinate of the polarization unit array plane.

[0042] The imaging lens group consists of one or more lenses and is used to image the object being photographed onto the image sensor chip of the polarization camera.

[0043] The polarization camera integrates a pixelated polarizer on the image sensor chip, and each pixel of the image sensor chip is covered with an analyzer unit of the analyzer polarizer. The number of analyzer angles included in the polarization camera is determined according to the actual application, and this embodiment does not impose specific restrictions. In a specific embodiment, the analyzer angles of all analyzer units are β1=0, β2=π / 4, β3=π / 2, β4=3π / 4 or β1=0, β2=2π / 3, β3=4π / 3, and are periodically repeated and covered on four or three adjacent pixels of the camera sensor chip; wherein the analyzer angle is the angle between the polarization direction of the analyzer unit and the spatial coordinate x' of the analyzer polarizer plane, and (x', y') represents the spatial rectangular coordinate of the analyzer polarizer plane.

[0044] The processor is connected to the surface light source and the polarization camera, and is used for controlling the illumination of the surface light source, the shooting of the polarization camera, the data storage and processing, and the image reconstruction.

[0045] Optionally, the polarizing polarizer comprises any one of a metal wire grid polarizing unit array, a liquid crystal polarizing unit array or a dichroic material polarizing unit array.

[0046] It should be noted that the polarizing polarizer includes but is not limited to a metal wire grid polarization unit array, a liquid crystal polarization unit array or a dichroic material polarization unit array.

[0047] Optionally, see Figure 1 The system further comprises an illumination lens group (13), wherein the illumination lens group (13) is arranged between the polarizing polarizer (12) and the target object (4).

[0048] The illumination lens group consists of one or more lenses and is used to irradiate the light beam emitted by the surface light source onto the target object.

[0049] Optionally, see Figure 4 The illumination lens group (13) comprises an illumination tube lens (131) and an illumination microscope objective lens (132).

[0050] Optionally, see Figure 5 The imaging lens group (21) comprises an imaging microscope objective lens (211) and an imaging tube lens (212).

[0051] Optionally, the surface light source includes an LED array light source, and the polarizing polarizer covers the surface of the LED array light source.

[0052] In a specific embodiment, the surface light source is an LED array light source, and the luminous brightness of each LED can be programmably controlled. The polarization unit of the polarizer covers the array unit of the LED array light source, wherein the LED is a light emitting diode.

[0053] See also Figure 6 The embodiment of the present invention provides a polarization multiplexed phase-shift structured illumination imaging method, which is applied to the above-mentioned imaging system, including:

[0054] S100: Single exposure to obtain an image captured by the polarization camera.

[0055] Before the polarization camera takes an image, the parameters of the components of the imaging system are set: the optical axis direction of the illumination lens group and the optical axis direction of the imaging lens group, the period T and period number Q of the polarization unit array of the polarizing polarizer, the width W in the x direction and the length L in the y direction of each polarization unit; the polarization direction of the polarization angle 0 of the polarizing polarizer, and the polarization direction of the polarization angle 0 of the polarization analyzer unit of the polarization camera; the target object is placed in the imaging device.

[0056] The polarization camera captures an image I(m,n): the surface light source is turned on, the emitted light beam is polarized by the polarizer, illuminates the target object, and the polarization camera captures the image to obtain an image I(m,n) with a pixel number of M×N, where M×N is the number of pixels on the photosensitive surface of the polarization camera, (m,n) is the pixel coordinate, 0≤m≤(M-1), 0≤n≤(N-1), and m, n, M, and N are all positive integers.

[0057] S200: split the captured image according to a plurality of polarization analysis angles to obtain a plurality of polarization sub-images.

[0058] Directly extract the polarization sub-image I from the image I(m,n) taken by the polarization camera k (m′, n′): According to the pixel polarization coding rule of the pixel polarizer, directly extract the pixel value with the same polarization angle. In a specific embodiment, three or four polarization sub-images with different polarization angles are split into I k (m′,n′), where k=0,1,2 or k=0,1,2,3.

[0059] S300, calculating the polarization sub-image to obtain a plurality of phase-shifted images.

[0060] In a specific embodiment, three or four images I are used. k (m′,n′) Get N S Phase shift image I k′ (m′,n′): Using 3 or 4 images I k (m′,n′), k=0,1,2 or k=0,1,2,3, the analysis angle β is obtained by calculation k′ =π(k′N S ) S Polarization sub-image Ik′ (m′,n′), the phase shift of two adjacent polarization sub-images is -2π(1 / N S ), N S Polarization sub-image I k′ (m′,n′) is N S Step phase shift image, where k′=0, 1, 2, ..., N S -1, N S is a positive integer greater than 4, (m′, n′) is the pixel coordinate, 0≤m′≤(M-1)2, 0≤n′≤(N-1) / 2, m′ and n′ are positive integers.

[0061] S400: Reconstruct a phase image or an intensity image of a target object according to a plurality of phase-shifted images.

[0062] In a specific embodiment, using N S Phase shift image I k′ (m′,n′),k′=0,1,2,...,N S -1, calculate the final image required for reconstruction.

[0063] Optionally, the phase shift image is calculated using the following formula:

[0064] I k′ (m′,n′)=I0(m′,n′)cos 2 β k′ +I2(m′,n′)sin 2 β k′ +[I1(m′,n′)-I3(m′,n′)]cosβ k′ sinβ k′

[0065] k′=0、1、2、...、N S -1

[0066] β k′ =π(k′ / N S )

[0067] Among them, I k' (m',n') represents the k'th phase-shifted image, β k' represents the k'th analysis angle, N S Represents the total number of phase-shifted images of a polarization sub-image. I0(m′,n′), I1(m′,n′), I2(m′,n′), and I3(m′,n′) are polarization sub-images with analysis angles of 0, π / 4, π / 2, and 3π / 4, respectively.

[0068] In a specific embodiment, the use of 4 images I k(m′,n′), k=0,1,2,3, the analysis angle β is obtained by calculation k′ =π(k′ / N S ) S Polarization sub-image I k′ (m′,n′), the calculation formula is: I k′ (m′,n′)=I0(m′,n′)cos 2 β k′ +I2(m′,n′)sin 2 β k′ +[I1(m′,n′)-I3(m′,n′)]cosβ k′ sinβ k′ , k′=0, 1, 2, ..., N S -1.

[0069] Optionally, the phase image or intensity image of the target object is reconstructed by the following formula:

[0070]

[0071] in, represents the phase image of the target object after reconstruction, and I(m′,n′) represents the intensity image of the target object after reconstruction.

[0072] The photographed target object is placed in an imaging device, and the fringe phase distribution image required for reconstruction is calculated and reconstructed. When the photographed target object is not placed in the imaging device or a standard target object is placed in the imaging device, the same steps as when the photographed target object is placed in the imaging device are used to calculate and reconstruct the phase distribution image of the fringe Then calculate the phase difference distribution image

[0073] Embodiment 1

[0074] This embodiment discloses a single-exposure polarization multiplexing phase-shifted structured illumination imaging system for three-dimensional profile measurement of a reflective target object. Figure 1 As shown, the imaging system comprises an illumination unit (1), an imaging unit (2) and a processor (3).

[0075] The lighting unit (1) is composed of a surface light source (11), a polarizing polarizer (12) and an illumination lens group (13). The surface light source (11) used is composed of a planar array LED light source and a light homogenizer, and the light beam emitted from each point of the light homogenizer contains all directions of linear polarization states. The polarizing polarizer (12) has a period T = 8, a period number Q = 8, and a polarization unit array composed of 64 straight strip dichroic material polarizers. Each straight strip polarization unit is 2 mm wide and 128 mm long. All polarizing units are arranged on a plane according to polarization angles α (i) of 0, π / 8, π / 4, 3π / 8, π / 2, 5π / 8, 3π / 4, 7π / 8, 0, π / 8, π / 4, 3π / 8, π / 2, 5π / 8, 3π / 4, 7π / 8, ..., with 8 angles forming one period, such as Figure 2 As shown (the arrow direction in the figure is the polarization direction of the polarization unit). The focal length of the illumination lens group (13) is 100 mm. (x, y) is the spatial rectangular coordinate of the polarization unit array plane of the polarizing polarizer (12), and the optical axis direction of the illumination unit (1) is the z spatial coordinate direction.

[0076] The imaging unit (2) is composed of an imaging lens group (21) and a polarization camera (23). The imaging lens group (21) is a zoom imaging lens group; the polarization camera (23) is a CMOS camera with a pixel size of 3.45um and a pixel number of 2448×2048. An array analyzer polarizer is integrated on the image sensor chip of the camera. Each pixel of the image sensor chip is covered with an analyzer unit of the array analyzer polarizer. All analyzer units are periodically arranged with four different linear polarizers with polarization angles β1=0, β2=π / 4, β3=π / 2, and β4=3π / 4. (x′, y′) is the spatial rectangular coordinate of the polarization unit array plane of the analyzer polarizer, and the optical axis direction of the imaging unit (2) is the z′ spatial coordinate direction.

[0077] Processor 3 is a desktop computer, and the execution steps are as follows:

[0078] S11, setting parameters of various components of the imaging system: setting the angle between the optical axis 14 of the illumination unit (1) and the optical axis (23) of the imaging unit (2) to 30 degrees; setting the period T=8 and the period number Q=8 of the polarization unit array of the polarizing polarizer (12); the width W=2 mm in the x direction and the length L=128 mm in the y direction of each polarization unit; the polarization direction of the polarization angle 0 of the polarizing polarizer (12) is consistent with the x direction, and the polarization direction of the polarization angle 0 of the polarization analyzing unit of the polarization camera is consistent with the x′ direction; and placing the target object in the imaging device.

[0079] S12, a polarization camera captures an image I(m,n): the surface light source (11) is turned on, the emitted light beam is polarized by the polarizer (12), and then illuminates the target object (4), and the polarization camera (22) captures the image to obtain an image I(m,n) with a pixel number of 2448×2048, wherein (m,n) is a pixel coordinate.

[0080] S13, directly extracting the polarization sub-image I from the image I(m,n) taken by the polarization camera k (m′, n′): from I(m, n) obtained by the polarization camera (22), according to the pixel polarization coding rule of the polarization camera, directly extract the pixel value with the same polarization angle, and obtain 4 polarization sub-images I with polarization angles of 0, π / 4, π / 2, and 3π / 4 respectively k (m′,n′), k=0,1,2,3,I k The phase shift between two adjacent images of (m′, n′) is (-2π / 4), (m′, n′) is the pixel coordinate, 0≤m′<(2448-1) / 2, 0≤n′<(2048-1) / 2, m′ and n′ are positive integers.

[0081] S14, using 4 images I k (m′,n′) Get N S Phase shift image I k′ (m′,n′): using 4 images I k (m′,n′), k=0,1,2,3, the calculation formula is:

[0082] I k′ (m′,n′)=I0(m′,n′)cos 2 β k′ +I2(m′,n′)sin 2 β k′ +[I1(m′,n′)-I3(m′,n′)]cosβ k′ sinβ k′

[0083] Calculate the analysis angle β k′ =π(k′ / N S ), k′=0, 1, 2..., 15, N S =16 polarization sub-image I k′ (m′,n′),I k′ The phase shift between two adjacent polarization sub-images (m′, n′) is -2π(1 / 16), and the 16 polarization sub-images I k′ (m′,n′) is a 16-step phase shift image; where N S =16 is just an exemplary value, not a limiting value.

[0084] S15, calculate and reconstruct the final image: using the 16-step phase shift image I k′ (m′,n′), k′=0, 1, 2…, 15, calculate the final image required for reconstruction. These 16 images I k′ The phase shift between two adjacent images (m′,n′) is (-2π / 16). According to the 16-step phase shift calculation formula:

[0085]

[0086] Calculate the fringe phase distribution image required for reconstruction According to the 16-step phase shift image calculation formula:

[0087]

[0088] Calculate the intensity image I(m′,n′) required for reconstruction; replace the target object (4) with a plane object as the standard target object, and follow the same steps as above to obtain the fringe phase distribution image Then calculate the phase difference distribution image:

[0089] Embodiment 2

[0090] This embodiment discloses a single-exposure polarization multiplexing phase-shifted structured illumination imaging system for three-dimensional profile measurement of a mirror-reflective target object. Figure 3 As shown, the imaging system comprises an illumination unit (1), an imaging unit (2) and a processor (3).

[0091] The lighting unit (1) is composed of a surface light source (11) and a polarizing polarizer (12). The surface light source (11) used is composed of a planar array LED light source and a light homogenizer, and the light beam emitted from each point of the light homogenizer contains all directions of linear polarization states. The polarizing polarizer 12 has a period T = 8, a period number Q = 8, and a polarization unit array composed of 64 straight strip dichroic material polarizers. Each straight strip polarization unit is 2 mm wide and 128 mm long. All polarizing units are arranged on a plane according to polarization angles α (i) of 0, π / 8, π / 4, 3π / 8, π / 2, 5π / 8, 3π / 4, 7π / 8, 0, π / 8, π / 4, 3π / 8, π / 2, 5π / 8, 3π / 4, 7π / 8, ..., with 8 angles as one period, such as Figure 1 As shown (the arrow direction in the figure is the polarization direction of the polarization unit), (x, y) is the spatial rectangular coordinate of the polarization unit array plane of the polarizing polarizer (12), and the optical axis direction of the illumination unit (1) is the z spatial coordinate direction.

[0092] The imaging unit (2) is composed of an imaging lens group (21) and a polarization camera (23). The imaging lens group (21) is a zoom imaging lens group; the polarization camera (23) is a CMOS camera with a pixel size of 3.45um and a pixel number of 2448×2048. An array analyzer polarizer is integrated on the image sensor chip of the camera. Each pixel of the image sensor chip is covered with an analyzer unit of the array analyzer polarizer. All analyzer units are periodically arranged with four different linear polarizers with polarization angles β1=0, β2=π / 4, β3=π / 2, and β4=3π / 4. (x′, y′) is the spatial rectangular coordinate of the polarization unit array plane of the analyzer polarizer, and the optical axis direction of the imaging unit (2) is the z′ spatial coordinate direction.

[0093] The processor 3 is a desktop computer, and the imaging system is used to perform imaging in the following steps:

[0094] S21, setting parameters of each component of the imaging system: setting the angle between the optical axis (14) of the illumination unit (1) and the optical axis (23) of the imaging unit (2) to 90 degrees; setting the period T=8 and the period number Q=8 of the polarization unit array of the polarizing polarizer (12); the width W=2 mm in the x direction and the length L=128 mm in the y direction of each polarization unit; the polarization direction of the polarization angle 0 of the polarizing polarizer 12 is consistent with the x direction, and the polarization direction of the polarization angle 0 of the polarization analyzing unit of the polarization camera is consistent with the x′ direction; the target object (4) is placed in the imaging device.

[0095] S22, a polarization camera captures an image I(m,n): the surface light source (11) is turned on, the emitted light beam is polarized by the polarizer (12), illuminates the target object (4), and the polarization camera (22) captures the image, thereby obtaining an image I(m,n) with a pixel number of 2448×2048, wherein (m,n) is a pixel coordinate.

[0096] S23, directly extracting the polarization sub-image I from the image I(m,n) taken by the polarization camera k (m′, n′): from I(m, n) obtained by the polarization camera (22), according to the pixel polarization coding rule of the polarization camera, directly extract the pixel value with the same polarization angle, and obtain 4 polarization sub-images I with polarization angles of 0, π / 4, π / 2, and 3π / 4 respectively k (m′,n′), k=0,1,2,3,I k The phase shift between two adjacent images of (m′, n′) is (-2π / 4), (m′, n′) is the pixel coordinate, 0≤m′<(2448-1) / 2, 0≤n′<(2048-1) / 2, m′ and n′ are positive integers.

[0097] S24, using 4 images I k(m′,n′) Get N S Phase shift image I k′ (m′,n′): using 4 images I k (m′,n′), k=0,1,2,3, the calculation formula is:

[0098] I k′ (m′,n′)=I0(m′,n′)cos 2 β k′ +I2(m′,n′)sin 2 β k′ +[I1(m′,n′)-I3(m′,n′)]cosβ k′ sinβ k′

[0099] Calculate the analysis angle β k′ =π(k′ / N S ), k′=0, 1, 2,..., 15, N S =16 polarization sub-image I k′ (m′,n′),I k′ The phase shift between two adjacent polarization sub-images (m′, n′) is -2π(1 / 16), and the 16 polarization sub-images I k′ (m′,n′) is a 16-step phase shift image; where N S =16 is just an exemplary value, not a limiting value.

[0100] S25, calculate and reconstruct the final image: using the 16-step phase shift image I k′ (m′,n′), k′=0, 1, 2, ..., 15, calculate the final image required for reconstruction. These 16 images I k′ The phase shift between two adjacent images (m′,n′) is (-2π / 16). According to the 16-step phase shift calculation formula:

[0101]

[0102] Calculate the fringe phase distribution image required for reconstruction A plane object is used as the standard target object, and the target object (4) is replaced. The fringe phase distribution image is obtained by following the same steps as above. Then calculate the phase difference distribution image

[0103] Embodiment 3

[0104] This embodiment discloses a single-exposure polarization multiplexing phase-shift structured illumination imaging system for transmission-type target object microscopic imaging. Figure 7The imaging system comprises an illumination unit (1), an imaging unit (2) and a computer (3).

[0105] The lighting unit (1) is composed of a surface light source (11), a polarizing polarizer (12), and a lighting lens group (13). The surface light source (11) is composed of an LED light source and a light homogenizer, and the light beam emitted from each point of the light homogenizer contains linear polarization states in all directions. The polarizing polarizer (12) is an array of 800 straight strip metal wire grid polarization units with a period T=8 and a period number Q=100, each straight strip polarization unit is 10um wide and 8000um long, and all polarizing units are arranged on a plane according to polarization angles α(i) of 0, π / 8, π / 4, 3π / 8, π / 2, 5π / 8, 3π / 4, 7π / 8, 0, π / 8, π / 4, 3π / 8, π / 2, 5π / 8, 3π / 4, 7π / 8, ..., with 8 angles forming one period. The illumination lens group (13) is composed of a tube lens (131) with a focal length of 180 mm and an objective lens (132) with a magnification of 10. Figure 4 As shown, the polarizing polarizer (12) is arranged on the front focal plane of the tube lens (131). (x, y) are the spatial rectangular coordinates of the polarization unit array plane of the polarizing polarizer (12), and the optical axis direction of the illumination unit (1) is the z spatial coordinate direction.

[0106] The imaging unit (2) is composed of an imaging lens group (21) and a polarization camera (23). The imaging lens group (21) is composed of an objective lens (211) with a magnification of 10 and a tube lens (212) with a focal length of 180 mm. Figure 5 As shown, the sensor chip of the polarization camera (12) is arranged on the rear focal plane of the tube lens (212); the polarization camera (23) is a CMOS camera with a pixel size of 345um and a pixel number of 2448×2048. An array analyzer polarizer is integrated on the image sensor chip of the camera. Each pixel of the image sensor chip is covered with an analyzer unit of the array analyzer polarizer. All analyzer units are periodically arranged by four different linear polarizers with polarization angles β1=0, β2=π / 4, β3=π / 2, and β4=3π / 4. (x′, y′) is the spatial rectangular coordinate of the plane of the polarization unit array of the analyzer polarizer, and the optical axis direction of the imaging unit (2) is the z′ spatial coordinate direction.

[0107] The processor 3 is a desktop computer, and the steps of performing imaging using the above imaging system are as follows:

[0108] S31, setting parameters of each component of the imaging system: setting the optical axis 14 of the illumination optical subsystem 1 and the optical axis 23 of the imaging optical subsystem 2 to be the same optical axis; setting the period T=8 and the period number Q=100 of the polarization unit array of the polarizing polarizer 12, the x-direction width W=10um, and the y-direction length L=8000um of each polarization unit; the polarization direction of the polarization angle 0 of the polarizing polarizer (12) is consistent with the x-direction, and the polarization direction of the polarization angle 0 of the polarization analyzing unit of the polarization camera is consistent with the x′ direction; the target object (4) is placed in the imaging device.

[0109] S32, a polarization camera captures an image I(m,n): the surface light source (11) is turned on, the emitted light beam is polarized by the polarizer (12), illuminates the target object (4), and the polarization camera (22) captures the image, thereby obtaining an image I(m,n) with a pixel number of 2448×2048, wherein (m,n) is a pixel coordinate.

[0110] S33, directly extracting the polarization sub-image I from the image I(m,n) taken by the polarization camera k (m′, n′): from I(m, n) obtained by the polarization camera (22), according to the pixel polarization coding rule of the polarization camera, directly extract the pixel value with the same polarization angle, and obtain 4 polarization sub-images I with polarization angles of 0, π / 4, π / 2, and 3π / 4 respectively k (m′,n′), k=0,1,2,3,I k The phase shift between two adjacent images of (m′, n′) is (-2π / 4), (m′, n′) is the pixel coordinate, 0≤m′<(2448-1) / 2, 0≤n′<(2048-1) / 2, m′ and n′ are positive integers.

[0111] S34, using 4 images I k (m′,n′) Get N S Phase shift image I k′ (m′,n′): using 4 images I k (m′,n′), k=0,1,2,3, the calculation formula is:

[0112] I k′ (m′,n′)=I0(m′,n′)cos 2 β k′ +I2(m′,n′)sin 2 β k′ +[I1(m′,n′)-I3(m′,n′)]cosβ k′ sinβ k′

[0113] Calculate the analysis angle β k′=π(k′ / N S ), k′=0, 1, 2,..., 7, N S =8 polarization sub-image I k′ (m′,n′),I k′ The phase shift between two adjacent polarization sub-images (m′, n′) is -2π(1 / 16), and the 8 polarization sub-images I k′ (m′,n′) is an 8-step phase shift image; where N S =8 is just an exemplary value, not a limiting value.

[0114] S35, calculate and reconstruct the final image: using the 8-step phase shift image I k′ (m′,n′), k′=0, 1, 2, ..., 7, calculate the final image required for reconstruction. These 8 images I k′ The phase shift between two adjacent images of (m′,n′) is (-2π / 8), which is calculated based on the 8-step phase shift image formula:

[0115]

[0116] Calculate the intensity image I(m′,n′) required for reconstruction.

[0117] The implementation of the embodiment of the present invention includes the following beneficial effects: the present embodiment uses a polarization unit array with multiple polarization angles as a polarizing polarizer to polarize the light beam emitted by the surface light source to form a polarization structured light beam with an uneven spatial distribution of polarization states, and uses the polarization structured light beam to illuminate the target object. The polarization camera takes an image of the polarized light beam passing through the target object with a single exposure, and according to the multiple polarization angles of the polarization camera, a plurality of polarization sub-images with different polarization states are separated from the captured image. These polarization sub-images can be used to obtain multiple phase-shifted fringe images by calculation, that is, multiple phase-shifted fringe images that need to be obtained by multiple exposures by the traditional phase shift method can be obtained by a single exposure; using these phase-shifted fringe images, the required image can be calculated and reconstructed. For example, the traditional 16-step phase-shifted structured illumination imaging technology requires 16 exposures to shoot 16 phase-shifted fringe images, and the imaging time is long, which is not conducive to imaging dynamic target objects. The single-exposure multi-step phase-shifted structured illumination imaging technology of the present invention greatly reduces the imaging time compared to the traditional multi-exposure multi-step phase-shifted structured illumination imaging technology, and can solve the imaging problem of dynamic target objects by the multi-step phase-shifted structured illumination imaging technology.

[0118] See also Figure 7 , an embodiment of the present invention provides a polarization multiplexed phase-shift structured illumination imaging device, comprising:

[0119] at least one processor;

[0120] at least one memory for storing at least one program;

[0121] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0122] Among them, the memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. The memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory may optionally include a remote memory remotely arranged relative to the processor, and these remote memories may be connected to the processor via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0123] It can be seen that the contents of the above method embodiments are all applicable to the present device embodiments, the functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0124] In addition, the embodiment of the present application also discloses a computer program product or a computer program, which is stored in a computer-readable storage medium. The processor of the computer device can read the computer program from the computer-readable storage medium, and the processor executes the computer program, so that the computer device performs the above method.

[0125] The embodiment of the present invention further provides a computer-readable storage medium, which stores a program executable by a processor, and the program executable by the processor is used to implement the above method when executed by the processor. Similarly, the contents of the above method embodiment are all applicable to the present storage medium embodiment, and the functions specifically implemented by the present storage medium embodiment are the same as those of the above method embodiment, and the beneficial effects achieved are also the same as those achieved by the above method embodiment.

[0126] It is understood that all or some steps and systems in the disclosed method above can be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, and the computer-readable medium can include a computer storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those of ordinary skill in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassette, magnetic tape, disk storage or other magnetic storage device, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0127] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A polarization multiplexed phase-shift structured illumination imaging system, characterized in that: The invention comprises an illumination unit, an imaging unit and a processor. The illumination unit comprises a surface light source and a polarizing polarizer. The imaging unit comprises an imaging lens group and a polarization camera. The light emitted by the surface light source comprises linear polarization states in multiple directions. The polarizing polarizer comprises a plurality of polarization units with polarization angles, and the polarization units are periodically arranged on a plane in a one-dimensional direction according to the polarization angles from 0 to π. The polarization camera comprises a plurality of analyzer units with analyzer angles. The light emitted by the surface light source reaches a target object through the polarizing polarizer. The light transmitted or reflected by the target object reaches the polarization camera through the imaging lens group for imaging. The processor is used to determine an image of the target object according to an image captured by the polarization camera.

2. The imaging system according to claim 1, characterized in that The polarizing polarizer includes any one of a metal wire grid polarizing unit array, a liquid crystal polarizing unit array, or a dichroic material polarizing unit array.

3. The imaging system according to claim 1, characterized in that The system further comprises an illumination lens group, wherein the illumination lens group is arranged between the polarizing polarizer and the target object.

4. The imaging system according to claim 3, characterized in that The illumination lens group comprises an illumination tube lens and an illumination microscope objective lens.

5. The imaging system according to claim 1, characterized in that The imaging lens group includes an imaging microscope objective lens and an imaging tube lens.

6. The imaging system according to claim 1, characterized in that: The surface light source includes an LED array light source, and the polarizing polarizer covers the surface of the LED array light source.

7. A polarization multiplexed phase-shift structured illumination imaging method, characterized in that: The imaging system according to any one of claims 1 to 6 comprises: Single exposure to obtain an image captured by the polarization camera; Splitting the captured image according to a plurality of polarization analysis angles to obtain a plurality of polarization sub-images; Calculating the polarization sub-image to obtain a plurality of phase-shifted images; A phase image or an intensity image of the target object is reconstructed according to the plurality of phase-shifted images.

8. The imaging method according to claim 7, characterized in that: The phase shift image is calculated by the following formula: I k′ (m′,n′)=I0(m′,n′)cos 2 b k′ +I2(m′,n′)sin 2 b k′ +[I1(m′,n′)-I3(m′,n′)]cosβ k′ sinβ k′ k′=0、1、2、...、N S -1 b k′ =π(k′ / N S ) Among them, I k '(m',n') represents the k'th phase shift image, βk' represents the k'th analysis angle, N S Represents the total number of phase-shifted images of a polarization sub-image. I0(m′,n′), I1(m′,n′), I2(m′,n′), and I3(m′,n′) are polarization sub-images with analysis angles of 0, π / 4, π / 2, and 3π / 4, respectively.

9. The imaging method according to claim 8, characterized in that: The phase image or intensity image of the target object is reconstructed by the following formula: in, represents the phase image of the target object after reconstruction, and I(m′,n′) represents the intensity image of the target object after reconstruction.

10. A polarization multiplexed phase-shift structured illumination imaging device, characterized in that: include: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method according to any one of claims 7 to 9.

Images