Disinfection by-product detection device based on polarization multiplexing self-interference holography

Abstract

The present invention discloses a disinfection byproduct detection device based on polarization multiplexing self-interference holography, which belongs to the technical field of disinfection byproduct detection. The detection device of the present invention includes a light source, a spectrometer, a filter, a lens, two polarizers, a spatial light modulator and a CCD camera. The light source emits green excitation light to illuminate the water body to be tested, exciting the fluorescent probe exposed to the disinfection byproduct environment. The yellow fluorescence reflected in the water body reaches the pure phase spatial light modulator after passing through the filter, the lens, and the first polarizer, realizing diffraction splitting and phase shift. The two beams of light interfere after passing through the second polarizer, and the interference fringes formed are recorded on the CCD. Subsequently, they are reconstructed on the computer side to obtain three-dimensional information of the luminous object. The device of the present invention uses holographic technology to achieve non-destructive detection, while avoiding the fragmentation problem of traditional self-interference holography, improving the image signal-to-noise ratio, and facilitating more accurate detection of disinfection byproducts.

Description

Technical Field

[0001] The present invention belongs to the technical field of disinfection by-product detection, and in particular relates to a disinfection by-product detection device based on polarization multiplexing self-interference holography. Background Art

[0002] In order to realize the recycling of water resources, ensure drinking water safety and kill pathogenic microorganisms in water that are harmful to health, disinfection has become a drinking water treatment process widely used in tap water plants.

[0003] With the discovery of chloroform among disinfection byproducts (DBPs) in 1974, people have gained a certain understanding of the types and toxicity of DBPs in drinking water. Currently, due to high levels of human activity, large amounts of self-generated or exogenous nutrients or persistent organic pollutants enter water bodies. This results in the generation of a wide variety of DBPs, such as haloacetic acids, haloacetonitriles, and trihalomethanes, after disinfection of drinking water, while chlorination eliminates microorganisms. These DBPs pose a potential threat to human health. Numerous toxicological and epidemiological studies have demonstrated that DBPs pose health risks, including carcinogenicity, genotoxicity, and reproductive toxicity. Therefore, conducting DBP detection and monitoring in drinking water is of great significance for ensuring drinking water safety.

[0004] Mixed DBPs in disinfected drinking water are no longer suitable for detection using conventional chemical analysis devices and single-endpoint toxicity analysis devices. Instead, fluorescent probe-based methods are used. Transcriptomic analysis of the effects of mixed DBPs after chlorination of water-derived organic matter on the genome-wide expression of human colon cancer cells Caco-2 revealed a strong association between two enzymes, cytochrome P450 family 1 subfamily A1 (CYP1A1) and cytochrome P450 family 1 subfamily B1 (CYP1B1), and mixed DBPs. Based on this observation, corresponding fluorescent probes were synthesized.

[0005] When using fluorescent probes synthesized based on DBPs biomarkers for mixed DBPs detection, since fluorescence is incoherent light, the incoherent correlation digital holography method can be used to observe the three-dimensional information of the luminous object. The existing incoherent correlation digital holography method uses the differential lens mask and constant phase mask of the spatial light modulator (SLM) for beam splitting. Since the two phase masks are randomly distributed on half of the pixels of the SLM, there is a fragmentation problem, which causes speckle noise in the hologram and reconstructed image, affecting the detection results. Summary of the Invention

[0006] The purpose of the present invention is to solve the technical problem in the prior art that when incoherent correlation digital holography is used to detect disinfection byproducts, the fragmentation of the spatial light modulator mask causes discontinuous or uneven phase modulation of the light wave, thereby generating speckle noise and affecting the imaging effect. A disinfection byproduct detection device based on polarization multiplexing self-interference holography is provided. The polarization multiplexing technology and the characteristics of the pure phase spatial light modulator as a polarization-sensitive element are used to solve the initial mask fragmentation problem, improve the hologram signal-to-noise ratio, and thus improve the image resolution, which helps to more clearly and accurately obtain and observe the three-dimensional information of luminous substances in water bodies.

[0007] The technical problem proposed by the present invention is solved as follows:

[0008] A disinfection byproduct detection device based on polarization multiplexing self-interference holography includes a light source, a spectrometer, a filter, a lens, two polarizers, a spatial light modulator, and a CCD camera. The water body to be tested, the spectrometer, the filter, the lens, the first polarizer P1, the spatial light modulator, the second polarizer P2, and the CCD camera are sequentially arranged on the same axis. The light source is located outside the axis, and the line connecting the light source and the spectrometer is perpendicular to the axis.

[0009] A solution prepared from a fluorescent probe synthesized for disinfection byproduct biomarkers is pre-added to the water to be tested and thoroughly mixed. A light source emits green laser light, which is reflected by a spectrometer and reaches the water to be tested. The green laser light is then refracted into the water to be tested, stimulating the fluorescent probe in the water to be tested. When the fluorescent probe is exposed to the disinfection byproducts and excited by the green laser light, it produces yellow fluorescence. The yellow fluorescence passes through the spectrometer and reaches a filter. The filter filters out green light interference and ambient light interference, and then collimates the light through a lens. The collimated light beam changes its polarization direction through a first polarizer P1 and reaches a pure phase spatial light modulator. Light with a polarization direction parallel to the active axis of the spatial light modulator is modulated, while light with a polarization direction perpendicular to the active axis is not modulated. Diffraction, splitting, and phase shifting are performed to produce a plane light beam and a spherical light beam with perpendicular polarization directions. The two light beams are then changed to the same polarization direction through a second polarizer P2, causing interference. The interference pattern of the plane light and the spherical light is recorded by a CCD camera. The recorded hologram is used to reconstruct three-dimensional information to complete the detection of disinfection byproducts in drinking water.

[0010] Furthermore, the wavelength of the green laser emitted by the light source is 535 nm, and the wavelength of the yellow fluorescence is 590 nm.

[0011] Furthermore, the beam splitter is a dichroic mirror, and the center wavelength of the filter is 590 nm.

[0012] Furthermore, the spatial light modulator is a polarization-sensitive pure phase spatial light modulator that only modulates polarized light whose polarization direction is parallel to the active axis of the spatial light modulator. All pixels on the spatial light modulator are only loaded with a differential lens mask.

[0013] Furthermore, the polarization directions of the two polarizers are consistent and are both at 45° relative to the active axis direction of the spatial light modulator.

[0014] Furthermore, when the interfering beams are plane beams and spherical beams, a point source Fresnel hologram is obtained. Light with a 45° angle with the polarization direction of the active axis of the pure phase spatial light modulator propagates to the spatial light modulator and is decomposed into two beams with polarization directions parallel and perpendicular to the active axis of the spatial light modulator. The light with parallel polarization direction is modulated by the phase mask loaded on the spatial light modulator, while the other light is not modulated. The output optical signal R(x,y) of the spatial light modulator is expressed as:

[0015]

[0016] Where x and y represent the horizontal and vertical coordinate variables of the output light signal, i is the symbol of the imaginary part, λ represents the central wavelength of the yellow fluorescence, θ is the phase constant, and a is the focal length of the pure phase spatial light modulator when it is equivalent to a lens system; the function Q represents the quadratic phase function, Q(b) = exp[iπb(x 2 +y 2 ) / λ] is used to simplify the formula, and b is the independent variable of function Q.

[0017] Furthermore, when the point source is located at (0,0,z s ), the distance between the point source and the lens is set to fz s , where f is the focal length of the lens, a value of the form Q[1 / (fz s )] divergent spherical wave; the transmission function of light propagating after the lens is Q(-1 / f), and the complex amplitude of the light wave after the lens is Q[1 / (fz s )]×Q(-1 / f)=Q{z s / [f(fz s )]}.

[0018] Furthermore, when the light propagates a distance d1 from the lens to the optical diffraction element of the spatial light modulator, the complex amplitude of the light wave is Q{z s / [f(fz s )+z sd1]}; After passing through the first polarizer P1, the angle between the polarization direction of the light and the active axis of the pure phase spatial light modulator is 45°. After passing through the spatial light modulator, the light is decomposed into two beams with perpendicular polarization directions. The polarization-sensitive pure phase spatial light modulator only modulates the light with the polarization direction parallel to the active axis. According to formula (1), after passing through the spatial light modulator, the complex amplitude of the light wave is equal to Q{z s / [f(fz s )+z s d1][1+Q(-1 / a)exp(iθ)]} association;

[0019] The two beams of light with perpendicular polarization directions pass through the second polarizer P2 to change their polarization states. The spherical light and plane light with the same polarization direction interfere with each other, and the interference pattern is recorded on the CCD camera plane at a distance d2 from the spatial light modulator. The recorded hologram I p (x,y) is:

[0020]

[0021] Where A is a constant coefficient and || represents modulo.

[0022] Furthermore, from the point source (0,0,z s ) recorded by the hologram, and generalized to a point source at any position (x s ,y s ,z s ), the recorded hologram can be expressed as:

[0023]

[0024] Among them, γ(z s )=[d2-az s (d1a+d2f-af+d2a-d1d2)f -2 ] / [1-z s (a+f-d1)f -2 ].

[0025] Furthermore, for the water body to be tested in the disinfection by-product detection, its three-dimensional position function is expressed as g(x s ,y s ,z s ), the two-dimensional hologram recorded by the CCD camera is expressed as:

[0026]

[0027] Among them, C is a constant term.

[0028] Furthermore, based on the phase shift technology, three holograms of the same water body to be tested are recorded. Each two-dimensional hologram corresponds to a different phase constant θ, thereby obtaining the final complex-valued hologram H of the water body to be tested. F (x,y) is represented as:

[0029]

[0030] Among them, H k (x,y) is the kth recorded hologram, and its phase constant is θ k , k=1,2,3.

[0031] Through the Fresnel propagation function, from the complex-valued hologram H F (x,y) to reconstruct a three-dimensional image s(x,y,z s ):

[0032]

[0033] Among them, the symbol * represents the convolution operation;

[0034] The reconstructed result s(x,y,z) obtained in formula (6) s ), from the three-dimensional image s(x,y,z s ) can observe the three-dimensional position and three-dimensional morphological information of the excited fluorescent probe in the water body to be tested, thereby realizing the detection of disinfection by-products based on polarization multiplexing self-interference holography.

[0035] The beneficial effects of the present invention are:

[0036] (1) The method of the present invention solves the technical problem that the conventional detection method of using fluorescent probes to study the toxicity of DBPs focuses on information such as fluorescence intensity and wavelength, while ignoring information such as the relevant position and morphology of the luminous object in three-dimensional space. The method can obtain three-dimensional information of the luminous object, which is conducive to in-depth research on DBPs.

[0037] (2) The method described in the present invention solves the technical problem of fragmentation caused by the random distribution of the phase mask of the spatial light modulator when the Fresnel incoherent correlation digital holography in the prior art is used for fluorescent probe detection of DBPs. Loading the differential lens mask on all pixels of the pure phase-type spatial light modulator can effectively avoid the fragmentation problem, reduce the noise level, and improve the signal-to-noise ratio of the reconstructed image, thereby obtaining clearer and more accurate DBPs detection results.

[0038] (3) The device of the present invention has a simple structure, is easy to implement, is convenient to operate, has high practicality, and is suitable for wide promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1Schematic diagram of the optical path of the disinfection by-product detection device of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and examples.

[0041] Disinfection byproducts (DBPs) in drinking water pose a threat to human health due to their carcinogenic, teratogenic, and mutagenic properties, attracting widespread attention worldwide. Using fluorescent probes for DBP detection, the probes, exposed to DBPs, generate a fluorescent signal upon exposure to the excitation light. This signal, combined with self-interference holography, enables non-destructive three-dimensional detection.

[0042] This embodiment provides a disinfection by-product detection device based on polarization multiplexing self-interference holography, and its optical path diagram is shown in FIG. Figure 1 As shown, it includes a light source, a beam splitter, a filter, a lens, two polarizers, a spatial light modulator and a CCD camera; the arrows in the figure indicate the polarization direction of the light; the water body to be measured, the beam splitter, the filter, the lens, the first polarizer P1, the spatial light modulator, the second polarizer P2 and the CCD camera are arranged in sequence on the same axis; the light source is located outside the axis, and the line connecting the light source and the beam splitter is perpendicular to the axis;

[0043] A solution prepared from a fluorescent probe synthesized for disinfection byproduct biomarkers is pre-added to the water to be tested and ensured to be fully mixed. A laser light source emits green light, which is reflected by a spectrometer and reaches the water to be tested. The green light is then refracted into the water to be tested, stimulating the fluorescent probe in the water to be tested. When the fluorescent probe is exposed to the disinfection byproducts and excited by the laser, the fluorescence signal changes, thereby generating yellow fluorescence. The yellow fluorescence passes through the spectrometer and reaches a filter. The filter filters out green light interference and ambient light interference. The light then passes through a lens, which is used to collimate the light. The collimated light beam changes its polarization direction through a first polarizer P1 and reaches a pure phase-type spatial light modulator. Light with a polarization direction parallel to the active axis of the spatial light modulator is modulated, while light with a polarization direction perpendicular to the active axis is not modulated. This method is used to perform diffraction, splitting, and phase shifting to obtain a beam of plane light and a beam of spherical light with perpendicular polarization directions. The two beams are then changed to the same polarization direction through a second polarizer P2, causing interference. The interference pattern of the plane light and the spherical light is recorded by a CCD camera.

[0044] In this embodiment, the wavelength of the green light source is 535 nm, the wavelength of the yellow fluorescent light is 590 nm, the beamsplitter is a dichroic mirror, and the center wavelength of the filter is 590 nm. The two polarizers are aligned, each at a 45° angle to the active axis of the phase-only spatial light modulator. All pixels on the spatial light modulator are masked with differential lenses.

[0045] When the interfering beams are plane beams and spherical beams, a point source Fresnel hologram is obtained, and the output optical signal R(x,y) of the spatial light modulator is expressed as:

[0046]

[0047] Where x and y represent the horizontal and vertical coordinate variables of the output light signal, i is the symbol of the imaginary part, λ represents the central wavelength of the yellow fluorescence, θ is the phase constant, and a is the focal length of the spatial light modulator when it is equivalent to a lens system; the function Q represents the quadratic phase function, Q(b) = exp[iπb(x 2 +y 2 ) / λ] is used to simplify the formula, b is the independent variable of function Q, and the constant term in formula (1) represents a plane wave, and the quadratic phase term represents a spherical wave.

[0048] When the point source is located at (0, 0, z s ), the focus of the lens is taken as the origin, and the distance between the point source and the lens is set to fz s , where f is the focal length of the lens, a value of the form Q[1 / (fz s )] divergent spherical wave. The transmission function of light propagating after the lens is Q(-1 / f), so the complex amplitude of the light wave after the lens is Q[1 / (fz s )]×Q(-1 / f)=Q{z s / [f(fz s )]}.

[0049] When the light propagates a distance d1 from the lens to the optical diffraction element of the spatial light modulator, the complex amplitude of the light wave becomes Q{z s / [f(fz s )+z s d1]}. After passing through the first polarizer P1, the polarization direction of the light is at an angle of 45° to the active axis of the pure phase SLM. After passing through the spatial light modulator, the light is decomposed into two beams with perpendicular polarization directions. The polarization-sensitive pure phase spatial light modulator only modulates the light with a polarization direction parallel to the active axis. According to formula (1), after passing through the optical diffraction element of the spatial light modulator, the complex amplitude of the wave is equal to Q{z s / [f(fz s )+z s d1][1+Q(-1 / a)exp(iθ)]} is related.

[0050] The two beams of light with perpendicular polarization directions cannot interfere with each other. After passing through the second polarizer P2, the spherical light and the plane light change to the same polarization direction and thus interfere with each other. The interference pattern is finally recorded on the CCD plane at a distance d2 from the spatial light modulator. The recorded hologram intensity I p(x,y) is:

[0051]

[0052] Where A is a constant coefficient and || represents modulo.

[0053] From the point source (0,0,z s ) can be extended to any point source (x s ,y s ,z s ), the recorded hologram can be expressed as:

[0054]

[0055] Among them, γ(z s )=[d2-az s (d1a+d2f-af+d2a-d1d2)f -2 ] / [1-z s (a+f-d1)f -2 ].

[0056] Furthermore, for any three-dimensional object, such as the water body to be tested in the disinfection byproduct detection, its three-dimensional position function is expressed as g(x s ,y s ,z s ), the two-dimensional hologram recorded by the CCD camera can be expressed as:

[0057]

[0058] Among them, C is a constant term.

[0059] In order to eliminate the problems of zero-order terms and conjugate images in the diffraction reconstruction process caused by the coaxial optical path, three holograms of the same object are recorded based on the phase shifting technology. Each hologram has a different phase constant θ, thereby obtaining the final complex-valued hologram H of the three-dimensional object. F (x,y) is represented as:

[0060]

[0061] Among them, H k is the kth recorded hologram, and the phase constant is θ k , k=1,2,3.

[0062] Through the Fresnel propagation function, the hologram H F (x,y) to reconstruct a three-dimensional image s(x,y,z s ), specifically expressed as:

[0063]

[0064] The symbol * represents the convolution operation.

[0065] The reconstructed result s(x,y,z) obtained in formula (6) s ), from which the three-dimensional position and three-dimensional morphology of the object and other related information can be observed, thereby realizing the detection of disinfection by-products based on polarization multiplexing self-interference holography.

[0066] A disinfection byproduct detection device based on polarization-multiplexed self-interference holography can determine the presence of disinfection byproducts in the water being tested and provide three-dimensional information about the luminescent object. During the detection process, when the water being tested contains disinfection byproducts, the fluorescent probe is exposed to the disinfection byproduct environment and stimulated by the excitation light to produce yellow fluorescence. Subsequently, a hologram is recorded using polarization-multiplexed self-interference holography to obtain three-dimensional information about the luminescent object.

[0067] In summary, the present invention is based on a disinfection byproduct detection device based on polarization multiplexing self-interference holography. When performing fluorescent probe detection of disinfection byproducts, the generated incoherent fluorescence can be effectively utilized to obtain a hologram, thereby realizing three-dimensional detection of objects. At the same time, polarization multiplexing and a polarization-sensitive pure phase-type spatial light modulator are used to avoid fragmentation problems, reduce image noise levels, thereby improving image reconstruction quality, and contributing to more accurate identification and detection of disinfection byproducts. The present invention has a wide range of applications and is suitable for vigorous promotion in this technical field or in technical fields close to this technical field.

[0068] The structures listed above are only basic structures of the present invention as examples and should not be used to limit the scope of protection of the present invention. Any changes or modifications that are made to the main design concept and spirit of the present invention and have no substantive significance, as long as the technical problems they solve are still consistent with the present invention, should be included in the scope of protection of the present invention.

Claims

1. A disinfection by-product detection device based on polarization multiplexing self-interference holography, characterized in that: The device comprises a light source, a beam splitter, a filter, a lens, two polarizers, a spatial light modulator, and a CCD camera; the water body to be measured, the beam splitter, the filter, the lens, the first polarizer P1, the spatial light modulator, the second polarizer P2, and the CCD camera are sequentially arranged on the same axis; the light source is located outside the axis, and the line connecting the light source and the beam splitter is perpendicular to the axis; A solution prepared from a fluorescent probe synthesized for disinfection byproduct biomarkers is pre-added to the water to be tested and thoroughly mixed. A light source emits green laser light, which is reflected by a spectrometer and reaches the water to be tested. The green laser light is then refracted into the water to be tested, stimulating the fluorescent probe in the water to be tested. When the fluorescent probe is exposed to the disinfection byproducts and excited by the green laser light, it produces yellow fluorescence. The yellow fluorescence passes through the spectrometer and reaches a filter. The filter filters out green light interference and ambient light interference, and then collimates the light through a lens. The collimated light beam changes its polarization direction through a first polarizer P1 and reaches a pure phase spatial light modulator. Light with a polarization direction parallel to the active axis of the spatial light modulator is modulated, while light with a polarization direction perpendicular to the active axis is not modulated. Diffraction, splitting, and phase shifting are performed to produce a plane light beam and a spherical light beam with perpendicular polarization directions. The two light beams are then changed to the same polarization direction through a second polarizer P2, causing interference. The interference pattern of the plane light and the spherical light is recorded by a CCD camera. The recorded hologram is used to reconstruct three-dimensional information to complete the detection of disinfection byproducts in drinking water.

2. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 1, characterized in that: The wavelength of the green laser emitted by the light source is 535nm, and the wavelength of the yellow fluorescence is 590nm.

3. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 1, characterized in that: The beam splitter is a dichroic mirror and the center wavelength of the filter is 590nm.

4. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 1, characterized in that: The spatial light modulator is a polarization-sensitive pure phase spatial light modulator that only modulates polarized light whose polarization direction is parallel to the active axis of the spatial light modulator. All pixels on the spatial light modulator are only loaded with a differential lens mask.

5. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 1, characterized in that: The polarization directions of the two polarizers are consistent and are both 45° relative to the active axis of the spatial light modulator.

6. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 1, characterized in that: When the interfering beams are plane beams and spherical beams, a point source Fresnel hologram is obtained. Light with a 45° angle to the polarization direction of the active axis of the pure phase spatial light modulator propagates to the spatial light modulator and is decomposed into two beams with polarization directions parallel and perpendicular to the active axis of the spatial light modulator. The light with parallel polarization direction is modulated by the phase mask loaded on the spatial light modulator, while the other light is not modulated. The output optical signal R(x,y) of the spatial light modulator is expressed as: Where x and y represent the horizontal and vertical coordinate variables of the output light signal, i is the symbol of the imaginary part, λ represents the central wavelength of the yellow fluorescence, θ is the phase constant, and a is the focal length of the pure phase spatial light modulator when it is equivalent to a lens system; the function Q represents the quadratic phase function, Q(b) = exp[iπb(x 2 +y 2 ) / λ] is used to simplify the formula, and b is the independent variable of function Q.

7. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 6, characterized in that: When the point source is at (0,0,zs), the distance between the point source and the lens is set to fz s , where f is the focal length of the lens, a value of the form Q[1 / (fz s )] divergent spherical wave; the transmission function of light propagating after the lens is Q(-1 / f), and the complex amplitude of the light wave after the lens is Q[1 / (fz s )]×Q(-1 / f)=Q{z s / [f(fz s )]}.

8. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 7, characterized in that: When the light propagates a distance d1 from the lens to the optical diffraction element of the spatial light modulator, the complex amplitude of the light wave is Q{z s / [f(fz s )+z s d1]}; After passing through the first polarizer P1, the angle between the polarization direction of the light and the active axis of the pure phase spatial light modulator is 45°. After passing through the spatial light modulator, the light is decomposed into two beams with perpendicular polarization directions. The polarization-sensitive pure phase spatial light modulator only modulates the light with the polarization direction parallel to the active axis. According to formula (1), after passing through the spatial light modulator, the complex amplitude of the light wave is equal to Q{z s / [f(fz s )+z s d1][1+Q(-1 / a)exp(iθ)]} association; The two beams of light with perpendicular polarization directions pass through the second polarizer P2 to change their polarization states. The spherical light and plane light with the same polarization direction interfere with each other, and the interference pattern is recorded on the CCD camera plane at a distance d2 from the spatial light modulator. The recorded hologram I p (x,y) is: Where A is a constant coefficient and || represents modulo.

9. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 8, characterized in that: From the point source (0,0,z s ) recorded by the hologram, and generalized to a point source at any position (x s ,y s ,z s ), the recorded hologram can be expressed as: where, γ(z s ) = [d2 - a - z s (d1a + d2f - af + d2a - d1d2)f -2 / [1 - z s (a + f - d1)f -2 .

10. The disinfection by-product detection device based on polarization multiplexing self-interference holography according to claim 9, characterized in that: For the water body to be tested in the detection of disinfection byproducts, its three-dimensional position function is expressed as g(x s ,y s ,z s ), the two-dimensional hologram recorded by the CCD camera is expressed as: Where C is a constant term; Based on the phase shift technology, three holograms of the same water body to be tested are recorded. Each two-dimensional hologram corresponds to a different phase constant θ, thereby obtaining the final complex-valued hologram H of the water body to be tested. F (x,y) is represented as: Among them, H k (x,y) is the kth recorded hologram, and its phase constant is θ k , k=1,2,3; Through the Fresnel propagation function, from the complex-valued hologram H F (x,y) to reconstruct a three-dimensional image s(x,y,z s ): Among them, the symbol * represents the convolution operation; The reconstructed result s(x,y,z) obtained in formula (6) s ), from the three-dimensional image s(x,y,z s ) can observe the three-dimensional position and three-dimensional morphological information of the excited fluorescent probe in the water body to be tested, thereby realizing the detection of disinfection by-products based on polarization multiplexing self-interference holography.

Images