Non-interference single-frame high-resolution phase recovery method and system based on weak object transmission equation

Abstract

The invention relates to a non-interference single-frame high-resolution phase recovery method and system based on a weak object transmission equation. The method comprises the following steps that a sample is placed on an objective table, an annular LED lamp panel, the sample, an objective lens, a barrel lens and a camera are sequentially placed in the direction of an optical axis, and light beams emitted by the LED lamp panel are received by a target surface of the camera after being transmitted by the sample, amplified by the objective lens and focused by the barrel lens; the illumination mode of the annular LED lamp panel is set to be a semi-annular asymmetric illumination mode, the annular LED lamp panel is turned on, and the camera shoots a light intensity image; calculating a phase transfer function in a semicircular asymmetric illumination mode according to a weak object light intensity transfer equation under the inclination angle illumination condition; and calculating a sample phase through a deconvolution algorithm according to the light intensity image and the phase transfer function. According to the invention, the data acquisition amount is small, the phase recovery is rapidly and stably realized, the phase information is complete, the resolution is high, and the non-interference rapid high-resolution phase recovery is effectively realized.

Description

Technical Field

[0001] This disclosure relates to the field of optical phase imaging technology, and in particular to a non-interference single-frame high-resolution phase retrieval method and system based on the weak object transmission equation. Background Technology

[0002] Optical phase carries crucial information such as an object's three-dimensional morphology and refractive index distribution. Non-interferometric, markerless phase measurement techniques do not rely on interference from an external reference beam; instead, they recover the phase by analyzing the intensity of the object light itself under different conditions. Typical methods include propagation methods based on the light intensity transmission equation, wavefront curvature sensing methods, and various computational imaging techniques (such as Fourier layered microscopy). These techniques typically possess common-path characteristics, resulting in simple system structures, high stability, and low requirements for light source coherence, demonstrating enormous application potential in fields such as biological microscopy, adaptive optics, and materials science.

[0003] However, traditional non-interferential phase retrieval techniques still have many limitations. For example, methods based on the light intensity transmission equation are difficult to integrate with high numerical aperture objectives and have limited resolution; methods such as differential phase contrast often result in the loss of low-frequency phase information; and scanning techniques such as Fourier layered microscopy face problems such as large data acquisition volume, long iterative algorithm time, and insufficient stability. Therefore, how to significantly reduce the amount of data acquisition and develop fast and robust phase retrieval methods while ensuring high resolution and integrity of phase information has become a key problem that urgently needs to be solved in this field. Summary of the Invention

[0004] Therefore, it is necessary to provide a non-interference single-frame high-resolution phase retrieval method and system based on the weak object transmission equation to address the above problems.

[0005] To solve the above problems, the present disclosure adopts the following technical solution: In a first aspect, this disclosure provides a non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation, comprising the following steps: The sample is placed on the stage, and the ring LED light panel, sample, objective lens, tube lens, and camera are placed sequentially along the optical axis. The center of the ring LED light panel and the illumination focal point are both located on the optical axis. The sample is located at the illumination focal point, and the light beam emitted by the LED light panel can illuminate the sample and then illuminate the objective lens after being transmitted through the sample. The objective lens is used to magnify the image, and the tube lens is used to focus the light beam onto the camera target surface. Set the lighting mode of the ring LED light panel to semi-ring asymmetrical lighting mode, turn on the ring LED light panel, and take a picture of the light intensity with the camera. Calculate the phase transfer function under semi-circular asymmetric illumination mode based on the light intensity transmission equation of weak objects under tilted angle illumination conditions. The sample phase is calculated using the deconvolution algorithm based on the light intensity image and the phase transfer function.

[0006] Secondly, this disclosure provides a non-interference single-frame high-resolution phase retrieval system based on the weak object transmission equation, the system comprising: an optical path system and a computing module; The optical path system includes a ring-shaped LED light panel, a stage, an objective lens, a tube lens, and a camera. The stage is used to place the sample. The ring-shaped LED light panel, sample, objective lens, tube lens, and camera are placed sequentially along the optical axis. The center of the ring-shaped LED light panel and the illumination focal point are both located on the optical axis. The sample is located at the illumination focal point. The light beam emitted by the LED light panel can illuminate the sample and, after transmission through the sample, illuminate the objective lens. The illumination mode of the ring-shaped LED light panel can be set to a semi-ring asymmetric illumination mode. The objective lens is used to magnify the image. The tube lens is used to focus the light beam onto the camera target surface. The camera is used to capture light intensity images. The calculation module is used to calculate the phase transfer function under the semi-circular asymmetric illumination mode based on the light intensity transmission equation of a weak object under tilted illumination conditions; and to calculate the sample phase using the deconvolution algorithm based on the light intensity image and the phase transfer function.

[0007] The aforementioned non-interference single-frame high-resolution phase retrieval method and system based on the weak object transmission equation calculates the phase transfer function based on the optical path under a semi-circular asymmetric illumination mode. According to the light intensity image and the phase transfer function, the sample phase is calculated through the deconvolution algorithm. This achieves the reconstruction of the sample phase based on a single image, combined with the phase transfer function and the deconvolution algorithm. It requires less data acquisition, achieves phase retrieval quickly and robustly, and provides complete phase information with high resolution, effectively realizing non-interference fast high-resolution phase retrieval. Attached Figure Description

[0008] Figure 1 This is a flowchart illustrating the non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation described in the embodiment. Figure 2 This is a schematic diagram of the non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation described in the embodiment. Figure 3 This is a schematic diagram of a semi-circular asymmetric lighting pattern in an embodiment. Figure 4 The grayscale image shows the phase transfer function under the semi-circular asymmetric illumination mode in the embodiment. Figure 5 The original light intensity image was captured for this example. Figure 6 A high-resolution phase image reconstructed for an example.

[0009] Explanation of reference numerals in the attached diagram: 1. Circular LED light panel; 2. Sample; 3. Objective lens; 4. Tube lens; 5. Camera. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation thereof.

[0011] It should be noted that, unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0012] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0013] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0014] See Figure 1 This disclosure provides a non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation, including: Sample 2 is placed on a stage. The annular LED light panel 1, sample 2, objective lens 3, tube lens 4, and camera 5 are then arranged sequentially along the optical axis. The center and focal point of the annular LED light panel 1 are both located on the optical axis. Sample 2 is positioned at the focal point. The light beam emitted by the LED light panel illuminates sample 2 and, after transmission through sample 2, illuminates objective lens 3. Objective lens 3 is used to magnify the image, and tube lens 4 is used to focus the light beam onto the target surface of camera 5. (See also...) Figure 2 ; The illumination mode of the ring-shaped LED light panel 1 was set to a semi-ring-shaped asymmetrical illumination mode. The ring-shaped LED light panel 1 was turned on, and the camera 5 captured a light intensity image. In reality, the ring-shaped LED light panel 1 and the sample 2 were parallel. Figure 2 The semi-circular asymmetrical lighting pattern is not shown in parallel, but only to illustrate the semi-circular asymmetrical lighting pattern of the ring LED light panel 1.

[0015] Calculate the phase transfer function under semi-circular asymmetric illumination mode based on the light intensity transmission equation of weak objects under tilted angle illumination conditions. Based on the light intensity image and the phase transfer function, the phase of sample 2 is calculated using a deconvolution algorithm.

[0016] Specifically, the non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation includes: Step 1: Place the ring LED light panel 1, stage, objective lens 3, tube lens 4, and camera 5 sequentially along the optical axis. Place the sample 2 on the stage so that the light from the ring LED light panel 1 passes sequentially through the sample 2, objective lens 3, and tube lens 4, and is imaged onto the target surface of the camera 5.

[0017] This is the optical path of a typical infinity microscope system. The objective lens 3 is the objective lens of the microscope, which serves to magnify the image.

[0018] The optical path principle is as follows: the ring LED light panel 1 is used to emit a light beam that illuminates the sample 2. The light beam emitted by the ring LED light panel 1 is focused onto the sample 2. The sample 2 projects the light beam, and the transmitted light beam is incident on the objective lens 3. After the image is magnified by the objective lens 3, it is incident on the tube lens 4. After the tube lens 4 is focused onto the target surface of the camera 5, the camera 5 captures the image.

[0019] It is understandable that Sample 2 is a phase resolution plate. Sample 2 itself has an image, and the image belongs to a high-contrast structure. That is to say, Sample 2 needs to have obvious intensity changes to provide sufficient phase gradient information. Usually, Sample 2 also contains multi-scale spatial frequencies to avoid phase solution ambiguity caused by a single frequency.

[0020] The center of the annular LED light panel 1 is located on the optical axis, and the annular LED light panel 1 has an illumination focal point, which is located on the optical axis; the sample 2 is located on the illumination focal point.

[0021] The ring-shaped LED light panel 1 includes a number of LED beads, which are grouped together as a lighting unit. For example, each LED bead serves as a lighting unit, and the LED beads are arranged along the center (uniformly) circumference of the ring, meaning the lighting units are arranged sequentially along the circumference. Preferably, all LED beads can illuminate the same point on the optical axis. Typically, the angle between the light emission direction of all LED beads and the optical axis is α, i.e., the angles are equal.

[0022] The distance between sample 2 (the intersection of the optical axis and sample 2) and the center of the annular LED light panel 1 satisfies the condition that the numerical aperture of the illumination is equal to the numerical aperture of the objective lens 3.

[0023] The fact that the numerical aperture of the illumination is equal to the numerical aperture of the objective lens 3 means that the angle at which the light emitted from the ring-shaped LED units illuminates the sample surface 2. satisfy

[0024] in, This indicates the numerical aperture of objective lens 3 (e.g., 0.8). The wavelength of the light source, Indicates the radius of the semi-circular light source. The distance between the ring-shaped LED light panel 1 and sample 2.

[0025] In this embodiment, the annular LED light panel 1 has a total of 48 LED beads evenly arranged around the center circumference, 60mm away from the center. In this preferred embodiment, see [reference needed]. Figure 3 Five LED beads, spaced 45° apart, are placed on the upper side of the ring-shaped LED light panel 1. The current values ​​are set to 10 mA, 20 mA, 40 mA, 80 mA, and 160 mA, respectively. The light source color is set to blue, and the center wavelength is 465 nm. They are set to illuminate simultaneously as a semi-ring-shaped asymmetrical illumination mode. Objective lens 3 is an Olympus 100× / 0.8NA objective lens. Camera 5 is a Dhyana 401D sCMOS camera from Xintu, with a target area size of 13.3 mm × 13.3 mm and a resolution of 2048 × 2048.

[0026] Specifically, focusing is used to position sample 2 on the focal plane in the X and Y directions ( Figure 3 Adjust the horizontal and vertical axes of the ring LED light panel 1 so that its center is on the optical axis. Adjust the Z-axis coordinate of the ring LED light panel 1 (the Z-axis is along the optical axis and perpendicular to the X and Y axes described below) so that its distance from the surface of sample 2 (that is, the distance between sample 2 and ring LED light panel 1) is [missing information]. = 45mm, which means that the numerical aperture of the illumination lens is equal to the numerical aperture of the objective lens 3, the exposure time of the camera 5 is adjusted to 100ms, and an image of 2048×2048 pixels is captured; Step 2: Set the lighting mode of the ring LED light panel 1 to a semi-ring asymmetrical lighting mode, turn on the ring LED light panel 1, and have the camera 5 capture a light intensity image. The ring-shaped LED light panel 1 comprises several lighting units, which are clearly LED lighting units. Specifically, several ring-shaped LED lighting units are lit simultaneously. These lighting units are arranged at equal angular intervals within a semi-circular region ranging from 0° to 180°, and their brightness varies from one another. The brightness of each lighting unit (e.g., several LEDs as a unit) in the semi-circular asymmetrical lighting mode is the sum of its individual brightness values. The following condition must be met: In this set, the sum of the elements of any subset will never equal the sum of the elements of another disjoint subset. That is, for any two subsets of the brightness set of lighting units, there must be no common elements. and ( ),satisfy:

[0027] in, and All represent the index of the lighting unit. Represents a set The total number of lighting units in the room Indicates the first lighting unit / lighting unit brightness, Indicates the first lighting unit / lighting unit The brightness.

[0028] Preferably, in the semi-circular asymmetric lighting mode, the brightness of each luminous unit in the circular LED light panel 1 forms a super-increasing sequence along the circumferential direction (counterclockwise or clockwise) (each item in the sequence must be greater than the sum of all preceding items).

[0029] Step 3: Calculate the phase transfer function under the semi-circular asymmetric illumination mode based on the light intensity transmission equation for weak objects under tilted illumination conditions. :

[0030]

[0031]

[0032]

[0033] in, Represents the imaginary unit. Indicates the number of the lighting unit. It also indicates the number of the lighting unit. Indicates the first The ratio of the brightness of an individual lighting unit to the brightness of the entire lighting mode. Represents the pupil function. It is a circular domain function used in optics to quantify the modulation effect of a circular aperture with radius 1 on transmitted light on an infinitely large opaque screen. Represents frequency domain coordinates, Indicates the first The wave vector of the plane wave emitted by each lighting unit. Indicates the total number of lighting units. For the first The set current for each lighting unit; Indicates the first The set current for each lighting unit; This indicates the numerical aperture of objective lens 3 (e.g., 0.8). The wavelength of the light source, Indicates the radius of the semi-circular light source. Indicates the first The X-axis rotation angle of each lighting unit relative to the ring-shaped LED light panel 1 The distance between the ring-shaped LED light panel 1 and sample 2; the X-axis and Y-axis are... Figure 3 The x and y axes are aligned with the diameter of the ring-shaped LED panel. The y-axis serves as the dividing axis between the illuminated and unilluminated semi-ringed areas in the semi-ringed asymmetrical lighting mode. The x-axis is perpendicular to the y-axis.

[0034] See Figure 4 , Figure 4 A grayscale image of the phase transfer function is shown as an example.

[0035] In the semi-circular asymmetric illumination mode, the cutoff frequency of the optical system, excluding the zero point, is... Within the range (i.e.) The optical system includes a ring-shaped LED light panel 1, a sample 2, an objective lens 3, a tube lens 4, and a camera 5; phase transfer function There is no non-zero region, meaning the formula is satisfied: .

[0036] Step 4: Using a deconvolution algorithm, extract the image and corresponding phase transfer function from camera 5 under the semi-circular asymmetric illumination mode. Calculate the phase of sample 2 ;

[0037]

[0038] in, This represents a captured image of light intensity. Represents the x-coordinate of a pixel in a light intensity image. Represents the ordinate of a pixel in a light intensity image; Indicates the positive Fourier transform. Indicates the inverse Fourier transform. express conjugate, This represents the regularization constant factor; Represents the Fourier transform of a normalized light intensity image. This indicates the operation of taking the average.

[0039] This disclosure provides a non-interference single-frame high-resolution phase retrieval system based on the weak object transmission equation. The system includes an optical path system and a computing module. The optical path system includes a ring LED light panel 1, a stage, an objective lens 3, a tube lens 4, and a camera 5. The stage is used to place a sample 2. The ring LED light panel 1, sample 2, objective lens 3, tube lens 4, and camera 5 are placed sequentially along the optical axis. The center and illumination focal point of the ring LED light panel 1 are both located on the optical axis. The sample 2 is located at the illumination focal point. The light beam emitted by the LED light panel can illuminate the sample 2 and, after transmission through the sample 2, illuminate the objective lens 3. The illumination mode of the ring LED light panel 1 can be set to a semi-ring asymmetric illumination mode. The objective lens 3 is used to magnify the image. The tube lens 4 is used to focus the light beam onto the target surface of the camera 5. The camera 5 is used to capture a light intensity image. The computing module is used to calculate the phase transfer function under the semi-ring asymmetric illumination mode according to the weak object light intensity transmission equation under tilted illumination conditions. It is also used to calculate the phase of sample 2 using a deconvolution algorithm based on the light intensity image and the phase transfer function.

[0040] In one specific embodiment, the image obtained by directly capturing the sample on the stage using a semi-circular asymmetric illumination mode is as follows: Figure 5 As shown, the high-resolution phase image recovered by the non-interferometric fast high-resolution phase retrieval method based on the weak object transmission equation provided in this disclosure is as follows: Figure 6 As shown.

[0041] The non-interferometric fast high-resolution phase retrieval method based on the weak object transmission equation provided in this disclosure achieves significantly enhanced contrast in the reconstructed high-resolution image after single-pass imaging and incorporating the deconvolution reconstruction algorithm. It accurately images the morphology of the phase resolution plate, clearly distinguishing the digits 11-4, indicating complete phase information and a substantial improvement in resolution. This non-interferometric fast high-resolution phase retrieval method based on the weak object transmission equation provided in this disclosure effectively achieves non-interferometric fast high-resolution phase retrieval.

[0042] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] The embodiments described above are merely illustrative of several implementations of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation, characterized in that, Includes the following steps: Place the sample on the stage, and place the ring LED light panel, sample, objective lens, tube lens, and camera in sequence along the optical axis. The center of the ring LED light panel and the illumination focal point are both located on the optical axis. The sample is located at the illumination focal point, and the light beam emitted by the LED light panel can illuminate the sample and then illuminate the objective lens after being transmitted through the sample. The objective lens is used to magnify the image, and the tube lens is used to focus the light beam onto the camera target surface. Set the lighting mode of the ring LED light panel to semi-ring asymmetrical lighting mode, turn on the ring LED light panel, and take a picture of the light intensity with the camera. Calculate the phase transfer function under semi-circular asymmetric illumination mode based on the light intensity transmission equation of weak objects under tilted illumination conditions. The sample phase is calculated using the deconvolution algorithm based on the light intensity image and the phase transfer function.

2. The non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation according to claim 1, characterized in that, The formula for calculating the phase transfer function is as follows: ； ； ； ； in, This represents the phase transfer function under a semi-annular asymmetric illumination mode. Represents the imaginary unit. and All of these represent the numbers of the lighting units. Indicates the first The ratio of the brightness of an individual lighting unit to the brightness of the entire lighting mode. Indicates the total number of lighting units. Represents the pupil function. Represents a circular domain function. Represents frequency domain coordinates, Indicates the first The wave vector of the plane wave emitted by each lighting unit. Indicates the first The set current of each lighting unit Indicates the first The set current of each lighting unit Indicates the numerical aperture of the objective lens. The wavelength of the light source, Indicates the radius of the semi-circular light source. Indicates the first The X-axis rotation angle of each lighting unit relative to the ring-shaped LED light panel. The distance between the ring-shaped LED light panel and the sample is shown. The X and Y axes are both oriented in the direction of the diameter of the ring-shaped LED light panel. The Y axis can be used as the dividing axis between the lighting mode and the non-lighting mode of the ring-shaped LED light panel in the semi-ring asymmetric lighting mode.

3. The non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation according to claim 2, characterized in that, The formula for calculating the sample phase is: ； ； in, Indicates the sample phase. This represents a captured image of light intensity. The x-coordinate of the pixel in the light intensity image. The vertical coordinate of the pixel in the light intensity image; Indicates the positive Fourier transform. Indicates the inverse Fourier transform. express conjugate, This represents the regularization constant factor; Represents the Fourier transform of a normalized light intensity image. This indicates the operation of taking the average.

4. The non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation according to claim 1, characterized in that, In the ring-shaped LED light panel under the semi-ring asymmetric lighting mode, the brightness sequence of each luminous unit along the circumference constitutes a super-increasing sequence.

5. The non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation according to claim 1, characterized in that, In the semi-circular asymmetric illumination mode, the phase transfer function The formula is not satisfied: ； in, This represents the phase transfer function under a semi-annular asymmetric illumination mode. Represents frequency domain coordinates, The cutoff frequency of the optical system is indicated. The optical system includes a ring-shaped LED light panel, a sample, an objective lens, a tube lens, and a camera.

6. The non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation according to claim 1, characterized in that, The annular LED light panel includes several lighting units arranged along the circumference.

7. The non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation according to claim 6, characterized in that, The annular LED light panel includes several lighting units arranged along the circumference, and the angle θ at which the light emitted by each lighting unit illuminates the sample table satisfies: ； in, Indicates the numerical aperture of the objective lens. The wavelength of the light source, Indicates the radius of the semi-circular light source. The distance between the ring-shaped LED light panel and the sample.

8. The non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation according to claim 6, characterized in that, For any two subsets of the brightness set of lighting units that have no common elements and ,satisfy: ； in, and All represent the index of the lighting unit. Indicates lighting unit brightness, Indicates lighting unit The brightness.

9. The non-interference single-frame high-resolution phase retrieval method based on the weak object transmission equation according to claim 6, characterized in that, In the semi-circular asymmetric lighting mode, all the lighting units that emit light are arranged at equal angular intervals within the semi-circular region.

10. A non-interfering single-frame high-resolution phase retrieval system based on the weak object transmission equation, characterized in that, The system includes: an optical path system and a computing module; The optical path system includes a ring-shaped LED light panel, a stage, an objective lens, a tube lens, and a camera. The stage is used to place the sample. The ring-shaped LED light panel, sample, objective lens, tube lens, and camera are placed sequentially along the optical axis. The center of the ring-shaped LED light panel and the illumination focal point are both located on the optical axis. The sample is located at the illumination focal point. The light beam emitted by the LED light panel can illuminate the sample and, after transmission through the sample, illuminate the objective lens. The illumination mode of the ring-shaped LED light panel can be set to a semi-ring asymmetric illumination mode. The objective lens is used to magnify the image. The tube lens is used to focus the light beam onto the camera target surface. The camera is used to capture light intensity images. The calculation module is used to calculate the phase transfer function under the semi-circular asymmetric illumination mode based on the light intensity transmission equation of a weak object under tilted illumination conditions; and to calculate the sample phase using the deconvolution algorithm based on the light intensity image and the phase transfer function.

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