Active focus module for pathological slice scanning equipment based on weak measurement

Abstract

The present invention discloses an active focusing module for a pathology slice scanning device based on weak measurement. The module emits incident light of a preset polarization state through a light source, which is divided into a first reference light and a detection light by a polarization beam splitter prism and a Wollaston prism. The first reference light is reflected by the lower surface of the cover glass to form a second reference light, and the detection light is reflected by the sample surface to form a sample light. The two then enter the Wollaston prism again for weak coupling and are combined into an outgoing light beam. The outgoing light is received by a spectrometer after phase modulation and polarization selection. The center of gravity offset of its bimodal spectrum can reflect the height variation of the sample surface, thereby achieving high-precision focusing. This technology utilizes the principle of weak measurement to convert tiny physical quantity changes into observable spectral offsets. The theoretical sensitivity reaches the picometer level, significantly improving the focusing accuracy and ensuring the clarity of the scanned image.

Description

Technical Field

[0001] The present invention relates to the technical field of microscopic scanning, and in particular to an active focusing module of a pathological slice scanning device based on weak measurement. Background Art

[0002] In the pathology diagnosis process, the quality of the scanned images of pathology sections plays a decisive role in the accurate diagnosis of the disease. Active focus technology is one of the key technologies of pathology section scanning equipment, and its focusing precision directly affects the clarity and accuracy of the image.

[0003] The active focusing technology of existing pathology slice scanning equipment mostly adopts traditional optical detection methods, such as optical coherence tomography or laser triangulation. These methods have certain limitations. The focusing method based on optical coherence tomography is easily affected by the differences in the optical properties of the tissue. The intensity and stability of the signal fluctuate greatly on different pathology tissue samples, resulting in focusing errors. When dealing with small fluctuations or transparent samples, the laser triangulation method has a weak reflected light signal, making it difficult to accurately capture subtle changes in the height of the sample surface, thus affecting the focusing accuracy. In addition, the traditional focusing method is not sensitive enough to the slight height changes of the sample surface in the complex pathology slice sample environment, resulting in difficulty in achieving accurate focusing on different height positions of the sample surface during the moving scanning process of the lens, and thus cannot meet the growing demand for high-precision pathology diagnosis.

[0004] Therefore, in active focusing technology, how to measure tiny height changes on the sample surface with high precision is a key problem that needs to be solved urgently to achieve precise focusing. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies in the prior art and to provide an active focusing module for a pathology slice scanning device based on weak measurement.

[0006] The objective of the present invention is achieved through the following technical solution: an active focus module of a pathology slice scanning device based on weak measurement, comprising a light source and a Wollaston prism, wherein the light emitted by the light source is modulated into incident light with a preset polarization state, the incident light passes through a polarization splitting prism and then is split into a first reference light and a detection light by the Wollaston prism, the polarization directions of the first reference light and the detection light being perpendicular, the first reference light being reflected by the lower surface of the cover glass to obtain a second reference light and entering the Wollaston prism again, the detection light being reflected by the sample surface to obtain a sample The light enters the Wollaston prism again, and the sample light and the second reference light are weakly coupled and combined into the outgoing light in the Wollaston prism. The outgoing light is reflected by the polarization beam splitter prism and the phase difference between the two beams in the outgoing light is adjusted to π / 2 by the phase modulator. The outgoing light after phase modulation is received by the spectrometer after polarization selection. The outgoing light is analyzed by the spectrometer to obtain the double-peak spectrum of the outgoing light. The center of gravity shift of the double-peak spectrum is used to calculate the fluctuation height change of the sample surface; focusing is performed according to the measured fluctuation height change of the sample surface.

[0007] Preferably, a quarter wave plate is provided between the Wollaston prism and the sample, the first reference light and the detection light emitted by the Wollaston prism pass through the quarter wave plate, the first reference light is reflected by the lower surface of the cover glass to obtain the second reference light, and the second reference light passes through the quarter wave plate, the detection light is reflected by the sample surface to obtain the sample light, and the sample light passes through the quarter wave plate; the polarization state of the incident reference light before passing through the quarter wave plate is perpendicular to the polarization state of the second reference light after passing through the quarter wave plate; the polarization state of the detection light before passing through the quarter wave plate is perpendicular to the polarization state of the sample light after passing through the quarter wave plate.

[0008] Preferably, an optical attenuator is provided between the Wollaston prism and the sample, and the first reference light and the second reference light pass through the optical attenuator, and the intensity of the second reference light is made consistent with the intensity of the sample light by the optical attenuator.

[0009] Preferably, a front selective polarizer is provided between the light source and the Wollaston prism, and a rear selective polarizer is provided between the phase modulator and the spectrometer.

[0010] Preferably, the wavelength of the light source is 830 nm.

[0011] Preferably, the distance between the sample light and the second reference light in the emitted light is 4 mm.

[0012] Preferably, the height variation of the sample surface is calculated by the following formula:

[0013] ;

[0014] Where, is the height variation of the sample surface, is the center-of-gravity offset of the double-peak spectrum, is the calibration coefficient.

[0015] Preferably, it is applied to microscopic scanning of pathological sections.

[0016] The beneficial effects of the present invention are:

[0017] 1. Based on weak measurement technology, the present invention can convert tiny changes in physical quantities (such as nanometer-level height differences) into observable spectral shifts. The theoretical sensitivity can reach the picometer level, and it can sensitively capture tiny height fluctuations on the sample surface, thereby providing a data basis for precise focusing, effectively improving the accuracy of focusing and ensuring the clarity of sample scanning.

[0018] 2. The spectral analysis speed is fast and can achieve millisecond-level response. It can track the surface fluctuations of the sample in real time and can effectively support dynamic focusing during high-speed scanning to meet the needs of high-throughput pathology analysis.

[0019] 3. The present invention adopts non-contact measurement technology and utilizes the reflection characteristics of polarized light to achieve non-contact measurement of the surface morphology of pathological sections, avoiding damage to the sample caused by mechanical contact, and is suitable for living tissue or fragile samples.

[0020] 4. Strong anti-environmental interference ability. Through polarization encoding and interferometry, it can effectively suppress ambient light noise and scattering interference, maintain high accuracy under low signal-to-noise ratio conditions, and effectively improve the reliability of detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the optical path structure of the present invention.

[0022] Figure 2 Schematic diagram of light reflection from the lower surface of the coverslip and the sample surface.

[0023] Figure 3 Schematic diagram showing that the center of gravity of the double-peak spectrum shifts as the height of the sample surface changes.

[0024] In the figure: 1. Light source, 2. Front-selective polarizer, 3. Polarization beam splitter, 4. Wollaston prism, 5. Quarter-wave plate, 6. Optical attenuator, 7. Phase modulator, 8. Rear-selective polarizer, 9. Spectrometer, 10. Cover glass, 11. Sample, 12. Sealant. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] It should be understood by those skilled in the art that, in the disclosure of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0027] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the elements may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0028] like Figures 1 to 2 As shown, the active focus module of the pathological slice scanning device based on weak measurement includes a light source 1 and a Wollaston prism 4. The light emitted by the light source 1 is modulated into an incident light with a preset polarization state. The incident light passes through the polarization splitting prism 3 and then is split into a first reference light and a detection light by the Wollaston prism 4. The polarization directions of the first reference light and the detection light are perpendicular. The first reference light is reflected by the lower surface of the cover glass 10 to obtain a second reference light and enters the Wollaston prism 4 again. The detection light is reflected by the surface of the sample 11 to obtain the sample 11 light and enters the Wollaston prism again. Wollaston prism 4, the sample 11 light and the second reference light are weakly coupled and combined into outgoing light in the Wollaston prism 4, the outgoing light is reflected by the polarization splitter prism 3 and the phase difference between the two beams of light in the outgoing light is adjusted to π / 2 by the phase modulator 7, the outgoing light after phase modulation is received by the spectrometer 9 after polarization selection, the outgoing light is analyzed by the spectrometer 9 and the double-peak spectrum of the outgoing light is obtained, and the height variation of the undulation on the surface of the sample 11 is calculated by the center of gravity offset of the double-peak spectrum; focusing is performed according to the measured height variation of the undulation on the surface of the sample 11.

[0029] Weak measurement is an indirect measurement method that differs from traditional measurement methods. In the theory of weak measurement, a pointer state is coupled to the system being measured. After the system evolves, the output pointer contains a value that can be read out as the measured parameter. By choosing appropriate pre-selected and post-selected states, this tiny separation can be amplified by a weak value and indirectly read out in the output pointer state.

[0030] The active focus module of the pathology slice scanning device based on weak measurement of the present invention performs high-sensitivity detection of tiny height changes on the surface of the sample 11 based on weak measurement technology, and realizes non-contact detection of the surface of the sample 11 through polarized light interference.

[0031] Light source 1 emits light of a specific wavelength. A polarizer selects the polarization of the light emitted by light source 1. The polarization-selected light is then modulated into incident light with a predetermined polarization state. The incident light then passes through polarization beam splitter prism 3 and enters Wollaston prism 4. Wollaston prism 4 decomposes the incident light into two linearly polarized beams with orthogonal polarization directions. The first reference light is vertically polarized, and the detection light is horizontally polarized. The split first reference light and detection light are spatially separated due to their orthogonal polarizations, but they maintain parallel propagation.

[0032] The first reference light is reflected by the lower surface of the cover glass 10 (the junction surface between the cover glass 10 and the sealing glue 12) to obtain the second reference light and enter the Wollaston prism 4 again. The detection light is reflected by the surface of the sample 11 to obtain the sample 11 light and enter the Wollaston prism 4 again. The sample 11 light and the second reference light are weakly coupled in the Wollaston prism 4 and combined into an outgoing light. Since the polarization orthogonality of the sample 11 light and the second reference light is maintained, the two beams of light are weakly coupled in the Wollaston prism 4 (that is, they are only weakly correlated through the polarization state to avoid strong interference) and are combined into a beam of outgoing light. The polarization state of the outgoing light emitted by the Wollaston prism 4 is opposite to the polarization state of the incident light. According to the characteristics of the polarization beam splitter prism 3, the outgoing light will be reflected by the polarization beam splitter prism 3. The outgoing light after being reflected by the polarization beam splitter prism 3 will pass through the phase modulator 7. The phase modulator 7 adjusts the phase difference between the two beams in the outgoing light to π / 2. When the phase difference between the two beams (the second reference light and the sample 11 light) is π / 2, the two are in orthogonal polarization states, which is used to meet the conditions for realizing a weak measurement system. At this time, they will form a stable intensity modulation during the interference process, which is convenient for extracting information through subsequent polarization analysis (later selection of polarizer 8). The orthogonal phase difference is used to reduce the disturbance of the measurement to the system, meeting the "low interference" requirement of weak measurement. If the phase difference between the two beams is not π / 2, the two beams may be in the same polarization state and interfere, resulting in a strong disturbance to the system during the measurement process (strong measurement), destroying the weak coupling condition, and having a greater negative impact on the system.

[0033] After phase modulation, the outgoing light undergoes polarization selection, at which point the weak measurement signal is amplified and received by the spectrometer 9. The outgoing light signal is analyzed by the spectrometer 9. Since the outgoing light contains the second reference light and the sample 11 light, a double-peak spectrum is formed in the spectrometer 9. The center of gravity of the double-peak spectrum (derived from the interference of the two beams of light) detected by the spectrometer 9 is directly related to the optical path difference between the second reference light and the sample 11 light, and the optical path difference between the second reference light and the sample 11 light is directly related to the surface height of the sample 11. Therefore, by analyzing the center of gravity offset of the double-peak spectrum, the height change of the surface of the sample 11 can be analyzed. By inputting the height change of the surface of the sample 11 into the control system, the control system controls the movement of the lens to compensate for the lens height, greatly improving the accuracy of the optical lens focus, thereby effectively improving the clarity of the scanning image.

[0034] The center of gravity of the double-peak spectrum refers to the weighted average position of the two peak wavelengths in the interference spectrum, which is directly related to the optical path difference between the two beams of light (the second reference light and the sample 11 light).

[0035] The linear response characteristics of the center of gravity position of the double-peak spectrum to the optical path difference enable height measurement accuracy to reach the sub-wavelength level (such as nanometer level), which is much higher than traditional optical focusing technology (such as the micron-level accuracy of laser triangulation), meeting the needs of high-resolution imaging of cell structures in pathological sections.

[0036] Traditional focusing techniques (such as contrast and defocus detection) are prone to failure when there are strongly reflective areas (such as the cell nucleus) or low-contrast areas (such as the cytoplasm) on the surface of the sample 11. However, this solution uses polarization state modulation and interference spectroscopy to separate the reference light and the sample 11 light using the polarization properties of light, avoiding interference from multiple layers of reflected light within the sample 11. It has greater adaptability to non-uniform and highly scattering biological tissues (such as adipose tissue and connective tissue), and can be widely used in the display and scanning of various biological pathology sections.

[0037] The Wollaston prism 4 employed in the present invention is a polarization optical device based on the birefringence effect, primarily used to decompose a beam of unpolarized light or polarized light into two beams of linearly polarized light with mutually perpendicular vibration directions, or to combine two beams of polarized light. In the present invention, the Wollaston prism 4 is positioned at a 45-degree angle to the horizontal interface. Its material is calcite.

[0038] Furthermore, a quarter wave plate 5 is arranged between the Wollaston prism 4 and the sample 11. The first reference light and the detection light emitted by the Wollaston prism 4 pass through the quarter wave plate 5. The first reference light is reflected by the lower surface of the cover glass 10 to obtain the second reference light, and the second reference light passes through the quarter wave plate 5. The detection light is reflected by the surface of the sample 11 to obtain the sample 11 light, and the sample 11 light passes through the quarter wave plate 5. The polarization state of the incident reference light before passing through the quarter wave plate 5 is perpendicular to the polarization state of the second reference light after passing through the quarter wave plate 5. The polarization state of the detection light before passing through the quarter wave plate 5 is perpendicular to the polarization state of the sample 11 light after passing through the quarter wave plate 5.

[0039] In the active focus module of the pathological slice scanning device based on weak measurement of the present invention, the core function of the 1 / 4 wave plate 5 is to convert the orthogonal linear polarized light into circularly polarized light through two phase delays (once at the time of injection and once at the time of emission) and use the reflected rotation direction to reverse, ultimately achieving orthogonal exchange of polarization states. This process allows the orthogonal polarized light that was originally separated by the path in the calcite prism to have its polarization states swapped and spatially overlapped after reflection, so that it can be combined into a beam of light, laying the foundation for subsequent light intensity detection, phase analysis or interferometry. In essence, the 1 / 4 wave plate 5 here plays the dual role of "polarization state converter" and "optical path control element."

[0040] In the present invention, the polarization states of the two orthogonally polarized beams are swapped by the quarter-wave plate 5, providing the conditions for subsequent beam combining. Without the phase delay effect of the first two quarter-wave plates 5, the polarization state of the reflected linearly polarized light remains unchanged (horizontally remains horizontal, vertically remains vertical), and the Wollaston prism 4 cannot combine them (because the orthogonal polarized light paths are separated in the prism). After conversion by the quarter-wave plate 5, the polarization state of the reflected light is orthogonally swapped, so that the polarization states of the two beams become orthogonal and spatially overlap in the calcite prism, meeting the beam combining conditions.

[0041] An optical attenuator 6 is provided between the Wollaston prism 4 and the sample 11 . The first reference light and the second reference light pass through the optical attenuator 6 , and the intensity of the second reference light is made consistent with the intensity of the sample 11 light by the optical attenuator 6 .

[0042] During the reflection process of the two beams of light (the first reference light and the detection light) at different interfaces, there will be multiple beams of reflected light (including the interface between the air and the upper surface of the coverslip 10, the interface between the coverslip 10 and the sealing glue 12, the interface between the sealing glue 12 and the surface of the sample 11, the interface between the sample 11 and the upper surface of the slide, the interface between the lower surface of the slide and the air, etc.), wherein the interface between the surface of the sample 11 and the sealing glue 12 is undulating, the interface between the coverslip 10 and the sealing glue 12 is flat, and the light intensities of different reflected lights are different. In the present invention, the interface between the coverslip 10 and the sealing glue 12 (i.e., the lower end face of the coverslip 10) is used as a reference surface, and the reference surface is used as a benchmark to detect the height changes of the undulations on the surface of the sample 11. In the present invention, the brightness of the reference light and the sample 11 light is adjusted to be consistent through an attenuator, and the measurement accuracy, dynamic range and robustness of the system are significantly improved by balancing the light intensities of the second reference light and the sample 11 light. In actual pathological section scanning, due to the large difference in reflectivity between the lower end surface of the coverslip 10 and the reflectivity of the surface of the sample 11, there is a large difference between the intensity of the second reference light and the intensity of the sample 11 light. This intensity difference will lead to a decrease in interference contrast and even cause double-peak distortion of the spectrum due to serious imbalance in signal intensity, which seriously affects the accurate calculation of the center of gravity offset of the double-peak spectrum.

[0043] In the actual process, since the light reflectivity of the lower end surface of the cover glass 10 (similar to mirror reflection) is higher than the reflectivity of the surface of the sample 11 (diffuse reflection), by setting the optical attenuator 6 on the optical path of the first reference light and the second reference light, the absorption and attenuation effect of the optical attenuator 6 on light is used to reduce the light intensity of the second reference light, so that the light intensity of the second reference light is consistent with that of the sample 11, thereby effectively balancing the light intensities of the two, avoiding the double-peak distortion of the spectrum due to serious imbalance in signal intensity, and improving the detection accuracy.

[0044] The optical attenuator 6 is an optical device that can accurately adjust the light intensity. The optical attenuator 6 attenuates the light power by absorbing, scattering or reflecting part of the light signal, thereby reducing the intensity of the light beam to the target value.

[0045] A front-selective polarizer 2 is placed between the light source 1 and the Wollaston prism 4, and a rear-selective polarizer 8 is placed between the phase modulator 7 and the spectrometer 9. The front-selective polarizer 2 rotates the polarization of the light emitted by the light source 1, thereby achieving a predetermined polarization state for the incident light. The rear-selective polarizer 8 selects the polarization of the outgoing light, eliminating interfering light and improving the detection sensitivity of the system.

[0046] The height variation of the sample surface is calculated using the following formula:

[0047] ;

[0048] Where, is the height variation of the sample surface, is the center-of-gravity offset of the double-peak spectrum, is the calibration coefficient. is a constant, Related to the wavelength range of the light source and the parameters of the optical components, The value of can be measured by experimental calibration method. The specific method is as follows:

[0049] Under laboratory conditions, use a standard sample of known height (such as a step sample) to scan and record the change in different heights The corresponding double peak spectrum center of gravity offset , then fit Curve, determine the calibration coefficient by fitting the curve The value of .

[0050] In this embodiment, the wavelength of the light source 1 is 830 nm. When using light of this specific wavelength of 830 nm, the detection accuracy of the undulation height of the sample surface can reach the picometer level.

[0051] In this embodiment, the sample light and the second reference light in the emergent light are parallel to each other, and the distance between the sample light and the second reference light in the emergent light is 4 mm.

[0052] In this embodiment, the active focus module of the pathology slice scanning device based on weak measurement is applied to microscopic scanning of pathology slices.

[0053] The present invention has the following advantages:

[0054] 1. Based on weak measurement technology, the present invention can convert tiny changes in physical quantities (such as nanometer-level height differences) into observable spectral shifts. The theoretical sensitivity can reach the picometer level, and it can sensitively capture tiny height fluctuations on the sample surface, thereby providing a data basis for precise focusing, effectively improving the accuracy of focusing and ensuring the clarity of sample scanning.

[0055] 2. The spectral analysis speed is fast and can achieve millisecond-level response. It can track the surface fluctuations of the sample in real time and can effectively support dynamic focusing during high-speed scanning to meet the needs of high-throughput pathology analysis.

[0056] 3. The present invention adopts non-contact measurement technology and utilizes the reflection characteristics of polarized light to achieve non-contact measurement of the surface morphology of pathological sections, avoiding damage to the sample caused by mechanical contact, and is suitable for living tissue or fragile samples.

[0057] 4. Strong anti-environmental interference ability. Through polarization encoding and interferometry, it can effectively suppress ambient light noise and scattering interference, maintain high accuracy under low signal-to-noise ratio conditions, and effectively improve the reliability of detection results.

[0058] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. Active focus module of pathology slice scanning equipment based on weak measurement, characterized by: The invention comprises a light source and a Wollaston prism. The light emitted by the light source is modulated into an incident light with a preset polarization state. The incident light passes through a polarization splitting prism and then is split into a first reference light and a detection light by a Wollaston prism. The polarization directions of the first reference light and the detection light are perpendicular. The first reference light is reflected by the lower surface of the cover glass to obtain a second reference light and enters the Wollaston prism again. The detection light is reflected by the sample surface to obtain a sample light and enters the Wollaston prism again. The sample light and the second reference light are weakly coupled in the Wollaston prism and are combined into an outgoing light. The incident light is reflected by a polarization beam splitter and the phase difference between the two beams of the outgoing light is adjusted to π / 2 by a phase modulator. The phase-modulated outgoing light is then polarization-selected and received by a spectrometer. The spectrometer analyzes the outgoing light and obtains a double-peak spectrum of the outgoing light. The height fluctuation of the sample surface is calculated by the center of gravity shift of the double-peak spectrum. Focusing is performed based on the measured height fluctuation of the sample surface. The center of gravity of the double-peak spectrum refers to the weighted average position of the two peak wavelengths in the interference spectrum, which is directly related to the optical path difference between the second reference light and the sample light. A quarter wave plate is provided between the Wollaston prism and the sample, the first reference light and the detection light emitted by the Wollaston prism pass through the quarter wave plate, the first reference light is reflected by the lower surface of the cover glass to obtain the second reference light, and the second reference light passes through the quarter wave plate, the detection light is reflected by the sample surface to obtain the sample light, and the sample light passes through the quarter wave plate; the polarization state of the incident reference light before passing through the quarter wave plate is perpendicular to the polarization state of the second reference light after passing through the quarter wave plate; the polarization state of the detection light before passing through the quarter wave plate is perpendicular to the polarization state of the sample light after passing through the quarter wave plate; an optical attenuator is provided between the Wollaston prism and the sample, the first reference light and the second reference light pass through the optical attenuator, and the light intensity of the second reference light is made consistent with the light intensity of the sample light by the optical attenuator; The height variation of the sample surface is calculated using the following formula: ； Where, is the height variation of the sample surface, is the center-of-gravity offset of the double-peak spectrum, is the calibration coefficient.

2. The active focus module of the pathological slice scanning device based on weak measurement according to claim 1, characterized in that A front selective polarizer is arranged between the light source and the Wollaston prism, and a rear selective polarizer is arranged between the phase modulator and the spectrometer.

3. The active focus module of the pathology slice scanning device based on weak measurement according to claim 1, characterized in that: The wavelength of the light source is 830 nm.

4. The active focus module of the pathology slice scanning device based on weak measurement according to claim 1, characterized in that The distance between the sample light and the second reference light in the emitted light is 4 mm.

5. The active focus module of the pathology slice scanning device based on weak measurement according to claim 1, characterized in that: Applied to microscopic scanning of pathological sections.

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