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

Abstract

The invention discloses a disinfection by-product detection device based on polarization multiplexing self-interference holography, and belongs to the technical field of disinfection by-product detection. The detection device comprises a light source, an optical splitter, an optical filter, a lens, two polaroids, a spatial light modulator and a CCD camera. A light source emits green exciting light to irradiate a water body to be detected to excite a fluorescent probe exposed in a disinfection by-product environment, yellow fluorescent light reflected from the water body passes through an optical filter, a lens and a first polaroid and then reaches a pure phase type spatial light modulator, diffraction light splitting and phase shifting are achieved, two beams of light interfere with each other after passing through a second polaroid, and the fluorescent probe is detected. And formed interference fringes are recorded on a CCD (Charge Coupled Device) and are subsequently reconstructed at a computer end, so that three-dimensional information of the luminous object can be obtained. According to the device, nondestructive testing is achieved through the holographic technology, meanwhile, the fragmentation problem of traditional self-interference holography is avoided, the signal-to-noise ratio of an image is increased, and disinfection by-products can be detected more accurately.

Description

Technical Field

[0001] The 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 the safety of drinking water and kill pathogenic microorganisms in the 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 a certain understanding of the types and toxicity of DBPs in drinking water. At present, due to high-load human activities, a large amount of self-generated or exogenous nutrients or persistent organic pollutants enter the water. This leads to the generation of a wide variety of DBPs, such as haloacetic acids, haloacetonitriles and trihalomethanes, after disinfection while chlorinating drinking water to eliminate microorganisms, posing a potential threat to human health. Many toxicological and epidemiological studies have shown that DBPs have health risks such as carcinogenicity, genotoxicity, and reproductive toxicity. Therefore, conducting drinking water DBPs detection and monitoring is of great significance to ensure drinking water safety.

[0004] Mixed DBPs in disinfected drinking water are no longer suitable for conventional chemical analysis devices and single endpoint toxicity analysis devices, but are detected using a fluorescent probe-based method. Based on transcriptomics analysis of the effects of mixed DBPs after chlorination of water source organic matter on the whole genome expression of human colon cancer cell Caco-2, it was found that two enzymes, cytochrome P450 family 1 subfamily A1 (CYP1A1) and cytochrome P450 family 1 subfamily B1 (CYP1B1), were strongly associated with mixed DBPs. Based on this phenomenon, corresponding fluorescent probes were synthesized.

[0005] When mixed DBPs detection is performed using fluorescent probes synthesized based on DBPs biomarkers, 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 incoherent correlation digital holography method in the prior art performs beam splitting through the differential lens mask and the constant phase mask of the spatial light modulator (SLM). 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 the reconstructed image, affecting the detection results. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problem that when incoherent correlation digital holography is used for disinfection water byproduct detection in the prior art, 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, which utilizes polarization multiplexing technology and the characteristics of a pure phase spatial light modulator as a polarization-sensitive element 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 the water body.

[0007] The technical problem proposed by the present invention is solved in this way:

[0008] A disinfection byproduct detection device based on polarization multiplexing self-interference holography comprises 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, a first polarizer P1, a spatial light modulator, a 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 between the light source and the spectrometer is perpendicular to the axis;

[0009] A solution prepared by synthesizing a fluorescent probe for a biomarker of disinfection byproducts is pre-added to a water body to be detected and mixed thoroughly; a light source emits a green laser, which is reflected by a spectrometer and reaches the water body to be detected, and then refracted into the water body to be detected to excite the fluorescent probe in the water body to be detected; when the fluorescent probe is exposed to the disinfection byproducts and excited by the green laser, yellow fluorescence is generated; the yellow fluorescence reaches the filter after passing through the spectrometer; 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 of the spatial light modulator is not modulated, and diffraction splitting and phase shift are completed to obtain a beam of plane light and a beam of spherical light with perpendicular polarization directions; the two beams of light are then changed to the same polarization direction through a second polarizer P2, and interference occurs; the interference pattern of the plane light and the spherical light is recorded by a CCD camera; three-dimensional information is obtained by reconstructing the recorded hologram 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 central wavelength of the filter is 590 nm.

[0012] Furthermore, the spatial light modulator is a polarization-sensitive pure phase spatial light modulator, which only modulates polarized light whose polarization direction is parallel to the active axis of the spatial light modulator, and 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 45° relative to the active axis direction of the spatial light modulator.

[0014] Furthermore, when the interference beam is a plane beam and a spherical beam, a point source Fresnel hologram is obtained, and the light with an angle of 45° with the polarization direction of the active axis of the pure phase spatial light modulator is transmitted to the spatial light modulator and is decomposed into two beams of light with polarization directions parallel and perpendicular to the active axis of the spatial light modulator. The light with parallel polarization directions is modulated by the phase mask loaded on the spatial light modulator, and the other light is not modulated. Then 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 Q[1 / (fz s )]; the transmission function of light propagating behind the lens is Q(-1 / f), and the complex amplitude of the light wave behind 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 of light 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 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. The interference pattern is finally 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, 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 byproduct detection, its three-dimensional position function is expressed as g(x s ,y s ,z s ), then 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, and 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 in the prior art of using fluorescent probes to study the toxicity of DBPs, the traditional detection method focuses on information such as fluorescence intensity and wavelength, but ignores 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 that when the prior art Fresnel incoherent correlation digital holography is used for fluorescent probe detection of DBPs, the random distribution of the phase mask of the spatial light modulator causes fragmentation. 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 in conjunction with the accompanying drawings and embodiments.

[0041] Disinfection byproducts in drinking water have carcinogenic, teratogenic and mutagenic properties, threatening human health and attracting widespread attention worldwide. When using fluorescent probes to detect disinfection byproducts, the fluorescent probes exposed to the disinfection byproduct environment are excited by the excitation light to generate fluorescent signals, which can be combined with self-interference holographic technology to perform non-destructive three-dimensional detection.

[0042] This embodiment provides a disinfection byproduct detection device based on polarization multiplexing self-interference holography, and its optical path schematic diagram is as follows 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 shown 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 between the light source and the beam splitter is perpendicular to the axis;

[0043] A solution prepared for synthesizing a fluorescent probe for a biomarker of disinfection byproducts is pre-added to a water body to be tested, and ensures that it is fully mixed; a laser light source emits green light, which is reflected by a spectrometer and reaches the water body to be tested, and then refracted into the water body to be tested, exciting the fluorescent probe in the water body to be tested; when the fluorescent probe is exposed to 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; then passes through a lens, which is used for light collimation; 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, and light with a polarization direction perpendicular to the active axis of the spatial light modulator is not modulated, and this method is used for diffraction, spectrometry and phase shifting to obtain a beam of plane light and a beam of spherical light with perpendicular polarization directions; the two beams of light are then changed to the same polarization direction through a second polarizer P2, thereby interfering; 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 535nm, the wavelength of the yellow fluorescence is 590nm, the beam splitter is a dichroic mirror, and the center wavelength of the filter is 590nm. The directions of the two polarizers are consistent, and both are 45° to the active axis of the pure phase-type spatial light modulator. All pixels on the spatial light modulator are loaded with differential lens masks.

[0045] When the interference beam is a plane beam and a spherical beam, a point source Fresnel hologram is obtained, and the output light 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 focal point 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 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 angle between the polarization direction of the light and the active axis of the pure phase SLM is 45°. After passing through the spatial light modulator, the light is decomposed into two beams of light 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. Finally, the interference pattern is 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 disinfection byproduct detection, its three-dimensional position function is expressed as g(x s ,y s ,z s ), then 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 remove 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, thus 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] Among them, 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] The disinfection byproduct detection device based on polarization multiplexing self-interference holography can determine whether the water body to be tested contains disinfection byproducts and provide three-dimensional information of the luminous object. During the detection process, when the water body to be tested contains disinfection byproducts, the fluorescent probe is exposed to the disinfection byproduct environment and is excited by the excitation light to produce yellow fluorescence. In the subsequent process, the hologram is recorded by the polarization multiplexing self-interference holography method to obtain the three-dimensional information of the luminous object.

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

[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, and 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 byproduct detection device based on polarization multiplexing self-interference holography, characterized in that: It 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 measured, the spectrometer, 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 between the light source and the spectrometer is perpendicular to the axis; A solution prepared by synthesizing a fluorescent probe for a biomarker of disinfection byproducts is pre-added to a water body to be detected and mixed thoroughly; a light source emits a green laser, which is reflected by a spectrometer and reaches the water body to be detected, and then refracted into the water body to be detected to excite the fluorescent probe in the water body to be detected; when the fluorescent probe is exposed to the disinfection byproducts and excited by the green laser, yellow fluorescence is generated; the yellow fluorescence reaches the filter after passing through the spectrometer; 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 of the spatial light modulator is not modulated, and diffraction splitting and phase shift are completed to obtain a beam of plane light and a beam of spherical light with perpendicular polarization directions; the two beams of light are then changed to the same polarization direction through a second polarizer P2, and interference occurs; the interference pattern of the plane light and the spherical light is recorded by a CCD camera; three-dimensional information is obtained by reconstructing the recorded hologram to complete the detection of disinfection byproducts in drinking water.

2. The disinfection byproduct 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 byproduct 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 byproduct 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, which 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 byproduct 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 direction of the spatial light modulator.

6. The disinfection byproduct detection device based on polarization multiplexing self-interference holography according to claim 1, characterized in that: When the interference beam is a plane beam and a spherical beam, a point source Fresnel hologram is obtained. The light with an angle of 45° 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 of light with polarization directions parallel and perpendicular to the active axis of the spatial light modulator. The light with parallel polarization directions is modulated by the phase mask loaded on the spatial light modulator, and the other beam of 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 byproduct 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 Q[1 / (fz s )]; the transmission function of light propagating behind the lens is Q(-1 / f), and the complex amplitude of the light wave behind the lens is Q[1 / (fz s )] × Q(-1 / f) = Q{z s / [f(fz s )]}.

8. The disinfection byproduct 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 of light 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 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. The interference pattern is finally 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 byproduct 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, 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 byproduct 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 disinfection byproduct detection, its three-dimensional position function is expressed as g(x s ,y s ,z s ), then the two-dimensional hologram recorded by the CCD camera is expressed as: Among them, 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