A method for calculating the refractive index of an oil film based on its degree of polarization.

Abstract

This invention discloses a method for calculating the refractive index of an oil film based on its polarization degree, comprising the following steps: acquiring multiple polarized images of sea surface oil spills at the same incident angle from the same light source; preprocessing the multiple polarized images of sea surface oil spills; using a polarization degree calculation method, obtaining the polarization degree of a simulated sea surface oil film image based on the preprocessed polarized images of sea surface oil spills; obtaining the relationship between the refraction angle and the incident angle of the light source according to Snell's law of refraction; calculating and deriving the Fresnel reflection coefficient and transmission coefficient formulas for s-wave and p-wave polarized light between the two medium surfaces of the air layer and the floating oil film layer; obtaining the Fresnel reflectivity of the s-wave and p-wave of the light source based on the Fresnel reflectivity and transmissionivity between the two medium surfaces of the air layer and the floating oil film layer; obtaining the relationship between the refraction angle and the incident angle, and the relationship between the Fresnel reflectivity and the polarization degree of s-wave and p-wave, according to Snell's law of refraction, thereby obtaining the refractive index of the oil film.

Description

Technical Field

[0001] This invention belongs to the field of marine environmental monitoring technology and relates to a method for calculating the refractive index of an oil film based on the degree of polarization of the oil film. Background Technology

[0002] With the development of shipping, the maritime industry has become an increasingly important part of transportation, leading to a surge in the number of ships sailing at sea. However, in recent years, numerous large and medium-sized oil spills have occurred globally, causing incalculable damage to marine ecosystems and the marine economy. Currently, most domestic and international marine monitoring centers use optical remote sensing technology to detect and identify oil spill areas and types. Research using traditional optical remote sensing methods for oil spill monitoring has yielded some practical results, primarily utilizing the spectral data of oil films to identify different types of oil films forming on the sea surface. In the field of oil film identification, measuring the refractive index of the oil film is a crucial technique, as different types of oil films have different refractive indices; therefore, refractive index is a characteristic parameter for identifying oil film types. Traditional oil film refractive index testing methods typically require expensive equipment or complex experimental procedures. To address this issue, a simple, fast, and economical method for testing the refractive index of oil films is needed. Summary of the Invention

[0003] To solve the above problems, the technical solution adopted by the present invention is: a method for calculating the refractive index of an oil film based on the degree of polarization of the oil film, comprising the following steps:

[0004] Acquire multiple polarization images of oil spills on the sea surface under the same light source and the same incident angle;

[0005] Preprocessing of multiple polarization images of oil spills on the sea surface;

[0006] The polarization degree of the simulated oil slick image on the sea surface was obtained by using the polarization degree calculation method based on the preprocessed polarization image of the oil spill on the sea surface.

[0007] The relationship between the angle of refraction and the angle of incidence of this light source is obtained based on Snell's law of refraction.

[0008] The Fresnel reflection and transmission coefficients of S-wave and P-wave polarized light between the two medium surfaces of the air layer and the oil film layer were calculated and derived.

[0009] Based on the Fresnel reflection and transmission coefficients between the two medium surfaces of the air layer and the floating oil film layer, and based on the oil film reflectivity formula, the Fresnel reflectivity of the s-wave and p-wave of the light source is obtained.

[0010] Based on Snell's law of refraction, the relationship between the angle of refraction and the angle of incidence, as well as the relationship between the Fresnel reflectivity and the degree of polarization of s-waves and p-waves, are obtained, thereby obtaining the oil film refractive index corresponding to different wavelengths.

[0011] Furthermore, the relationship between the angle of refraction and the angle of incidence is as follows:

[0012]

[0013] in: It is the refractive index of the air layer; It is the refractive index of the oil film; Angle of incidence; It is the angle of refraction.

[0014] Furthermore, the calculations derived the following formulas for the Fresnel reflection and transmission coefficients of S-wave and P-wave polarized light between the two dielectric surfaces of the air layer and the floating oil film layer:

[0015]

[0016]

[0017] in: It is the reflection coefficient of the S-wave. The reflection coefficient of the p-wave, Transmission coefficient of p-wave.

[0018] Furthermore, the Fresnel reflectance formulas for the s-wave and p-wave of the light source are as follows:

[0019]

[0020]

[0021] in: It is the reflection coefficient of the S-wave on the surface of the oil film. It is the transmission coefficient of the S-wave on the upper surface of the oil film. It is the transmission coefficient of an S-wave as it passes through the air onto the upper surface of the oil film layer. It is the reflection coefficient of the P-wave on the upper surface of the oil film; It is the transmission coefficient of the P-wave on the upper surface of the oil film. The transmission coefficient of a P-wave as it passes through the upper surface of the oil film and into the air; i represents the imaginary part of the refractive index; a represents the extinction coefficient of the oil film; and s represents the optical path length of light within the oil film. KΔ represents the phase delay between the two beams of light. , , The measured oil film thickness, R is the wavelength of the incident light. s It is the S-wave reflectivity, R P It is P-wave reflectivity.

[0022] Furthermore, the relationship between the Fresnel reflectivity of the S-wave and the P-wave and the degree of polarization P is as follows:

[0023]

[0024] Where: R s It is the S-wave reflectivity, R P It is P-wave reflectivity.

[0025] An apparatus for calculating the refractive index of an oil film based on its degree of polarization, comprising:

[0026] Acquisition module: used to acquire multiple polarization images of oil spills on the sea surface under the same incident angle from the same light source;

[0027] Preprocessing module: Used to preprocess multiple polarization images of oil spills on the sea surface;

[0028] Calculation Module I: Used to calculate the polarization degree of the simulated oil slick image on the sea surface based on the preprocessed polarization image of the oil spill on the sea surface using the polarization degree calculation method;

[0029] Calculation Module II: Used to obtain the relationship between the angle of refraction and the angle of incidence of the light source according to Snell's law of refraction;

[0030] Calculation Module III: Used to calculate and derive the Fresnel reflection and transmission coefficients of S-wave and P-wave polarized light between the two medium surfaces of the air layer and the floating oil film layer;

[0031] Calculation Module IV: Based on the Fresnel reflection and transmission coefficients between the two medium surfaces of the air layer and the floating oil film layer, and based on the oil film reflectivity formula, the Fresnel reflectivity of the s-wave and p-wave of the light source is obtained.

[0032] Calculation module V: Based on Snell's law of refraction, the relationship between the angle of refraction and the angle of incidence, as well as the relationship between the Fresnel reflectivity and the degree of polarization of s-waves and p-waves, are obtained, thereby obtaining the oil film refractive index corresponding to different wavelengths.

[0033] This invention provides a method for calculating the refractive index of an oil film based on its polarization degree. This method calculates the refractive index of an oil film based on the polarization degree of an optical polarization image of the oil film on the sea surface. After comparing the calculated refractive index with existing oil film refractive indices, it can be used to detect and identify the types of marine oil spills. Specifically, this method is based on seawater oil spill experiments, obtaining polarization images of the oil film on the sea surface, extracting the polarization degree of the polarization image, and using a physical model based on Fresnel's reflection formula combined with oil spill simulation test data to analyze the refractive index of the oil film. According to the refractive index range of different types of oil films, the calculated value is compared with known oil film refractive indices to determine the type of oil film. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is the optical path diagram simulating an oil spill at sea surface in this invention;

[0036] Figure 2 This is a flowchart of the method;

[0037] Figure 3 This is a diagram of the refractive index of the oil film corresponding to different wavelengths. Detailed Implementation

[0038] It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0042] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0043] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0044] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0045] Figure 1This is the optical path diagram simulating an oil spill at sea surface in this invention.

[0046] The experimental platform is set up roughly as follows: Figure 1 As shown, experimental data acquisition should be conducted in a dark room to minimize interference from external background light on the optical measurement of oil slicks on the sea surface. This experiment uses two identical tripods to mount the light source and polarization camera respectively. A filter is installed in front of the polarization camera, filtering wavelengths of 522-542nm and 640-660nm. Before data acquisition, the lens is focused to ensure a clear image of the oil film. A square basin filled with seawater is used to simulate the sea surface. To reduce interference from reflected light beams at the bottom and sides of the basin, the sample oil container is completely wrapped with black tape. The light source is a 150W built-in imported xenon lamp with a wide spectral range. Because its color temperature is close to that of sunlight, it can be used to simulate natural light. A polarization camera is used to acquire polarized images of the oil film.

[0047] Figure 2 This is a flowchart of the method;

[0048] A method for calculating the refractive index of an oil film based on its degree of polarization includes the following steps:

[0049] S1: Acquire multiple polarization images of oil spills on the sea surface under the same light source and the same incident angle;

[0050] S2: Preprocess multiple polarization images of oil spills on the sea surface;

[0051] S3: Using the polarization degree calculation method, the polarization degree of the simulated oil slick image on the sea surface is obtained based on the preprocessed polarization image of the sea surface oil spill.

[0052] S4: Based on Snell's law of refraction, obtain the relationship between the angle of refraction and the angle of incidence of this light source;

[0053] S5: Based on Maxwell's equations, the Fresnel reflection and transmission coefficients of s-wave and p-wave polarized light between the two medium surfaces of the air layer and the oil film layer are calculated and derived.

[0054] S6: Based on the Fresnel reflection coefficient and transmission coefficient between the two medium surfaces of the air layer and the floating oil film layer, and based on the oil film reflectivity formula, the Fresnel reflectivity of the s-wave and p-wave of the light source is obtained.

[0055] S7: Based on Snell's law of refraction, the relationship between the angle of refraction and the angle of incidence, as well as the relationship between the Fresnel reflectivity and the degree of polarization of s-waves and p-waves, are obtained, thereby obtaining the oil film refractive index corresponding to different wavelengths.

[0056] Steps S1 / S2 / S3 / S4 / S5 / S6 / S7 are executed sequentially;

[0057] The preprocessing process involves repeatedly measuring the polarization image of the oil spill on the same sea surface. The polarization degree of the oil film is generally between 1.5 and 2.0. Data with a large error in polarization degree are discarded.

[0058] The polarization degree of the oil film polarization image on the sea surface is obtained by calculating the average value of the data under each group of incident light angles.

[0059] On a calm sea surface, an oil film forms a three-layer medium: air, oil film, and seawater. These three media have significantly different refractive indices. Incident light is refracted and reflected within the oil film layer. Therefore, the floating oil film on the water surface can be considered a uniform parallel plate, with the first layer being the air layer, whose refractive index is... The middle layer is an oil film, and the refractive index of the oil film is... The oil film thickness is The bottom layer is the seawater layer, and its refractive index is [missing information]. The oil film thickness is d.

[0060] When a beam of light enters the oil film layer from air, transmission occurs. According to Snell's law of refraction, the relationship between the angle of refraction and the angle of incidence is obtained as follows:

[0061] (1)

[0062] Then, the formulas for the Fresnel reflection coefficient and transmission coefficient of s-wave and p-wave polarized light between two medium surfaces are calculated and derived:

[0063] (2)

[0064] (3)

[0065] It is the refractive index of the air layer; It is the refractive index of the oil film; Angle of incidence; It is the angle of refraction;

[0066] When incident light enters the oil film layer from the air layer, the transmittance of the upper surface of the oil film is... The reflectivity of the upper surface of the oil film is When transmitted light from within the oil film enters the interface between the oil film and seawater, i.e., when it enters the lower surface of the oil film, the reflectance of the lower surface of the oil film is... When transmitted light within the oil film is reflected from the lower surface of the oil film and then transmitted through the upper surface of the oil film into the air, its transmittance is... The electric vector intensity of the first reflection of the incident light on the surface of the oil film. The photoelectric vector intensity transmitted into the oil film for the first time is The electric vector intensity of the transmitted light after reflection from the lower surface of the oil film is: The transmitted light in the oil film layer is reflected by the lower surface of the oil film, then transmitted through the upper surface of the oil film to the air layer, and its electric vector intensity is... Considering and The propagation path has a length of Δ The difference lies in the phase delay between the two beams. KΔ If the extinction coefficient of the light beam during its propagation through the oil film layer is... a If the two-beam interference of light reflected from the lower surface of the oil film results in a beam reflected back into air with a propagation path length S within the oil film, then the transmitted photoelectric vector intensity is: Parallel plate interference, also known as reflected light. With oil film emitted light The superposition of their electric vectors produces two-beam interference. At the detector's focal plane, and Superposition produces interference, and the electric vector entering the remote sensor system... Based on the traditional two-beam interference model, the oil film reflectivity R can be calculated as follows:

[0067] (4)

[0068] Where: i represents the imaginary part of the refractive index; a represents the oil film extinction coefficient; s represents the optical path length of light within the oil film. KΔ represents the phase delay between the two beams of light. , , The measured oil film thickness, λ is the wavelength of the incident light. The reflectance of the upper surface of the oil film. The transmittance of the oil film's upper surface is denoted as . : Reflectance coefficient of the lower surface of the oil film layer; The transmittance coefficient of the oil film layer when air is transmitted through its upper surface;

[0069] Traditional two-beam models have significant errors in actual measurements. Considering the scattering characteristics of the oil film's microscopic surface and the variation of the oil film's complex refractive index with wavelength, a corresponding influence factor s, namely the electromagnetic wave scattering coefficient, was added to the traditional two-beam model. This has yielded good results in the verification of the improved model.

[0070] The Fresnel reflectances of S-waves and P-waves can be obtained:

[0071] (5)

[0072] (6)

[0073] in: It is the reflection coefficient of the S-wave on the surface of the oil film. It is the transmission coefficient of the S-wave on the upper surface of the oil film. It is the transmission coefficient of an S-wave as it passes through the air onto the upper surface of the oil film layer. It is the reflection coefficient of the P-wave on the upper surface of the oil film; It is the transmission coefficient of the P-wave on the upper surface of the oil film. The transmission coefficient of a P-wave as it passes through the upper surface of the oil film and into the air; i represents the imaginary part of the refractive index; a represents the extinction coefficient of the oil film; s represents the optical path length of the light within the oil film. KΔ represents the phase delay between the two beams of light. , , The measured oil film thickness, R is the wavelength of the incident light. s It is the S-wave reflectivity, R P It is P-wave reflectivity;

[0074] According to Snell's law of refraction, the relationship between the angle of refraction and the angle of incidence is as follows: The reflectivity of S-waves and P-waves and Substitute into the formula for calculating the degree of polarization P:

[0075] (7)

[0076] Will and Substituting into the formula, the formula contains only the oil film thickness. and refractive index Given two unknowns, and considering that the degree of polarization changes with the incident angle at a fixed wavelength, for a single type of floating oil, the solution is to collect and calculate the different degrees of polarization at two different incident angles. The two equations can be solved simultaneously to determine the oil film thickness. and refractive index .

[0077] An apparatus for calculating the refractive index of an oil film based on its degree of polarization, comprising:

[0078] Acquisition module: Used to acquire multiple polarization images of oil spills on the sea surface under the same light source and the same incident angle;

[0079] Preprocessing module: Used to preprocess multiple polarization images of oil spills on the sea surface;

[0080] Calculation Module I: Used to calculate the polarization degree of the simulated oil slick image on the sea surface based on the preprocessed polarization image of the oil spill on the sea surface using the polarization degree calculation method;

[0081] Calculation Module II: Used to obtain the relationship between the angle of refraction and the angle of incidence of the light source according to Snell's law of refraction;

[0082] Calculation Module III: Used to calculate and derive the formulas for the Fresnel reflection and transmission coefficients of S-wave and P-wave polarized light between the two medium surfaces of the air layer and the floating oil film layer;

[0083] Calculation Module IV: Used to derive the oil film reflectivity formula based on the Fresnel reflection coefficient and transmission coefficient between the two medium surfaces of the air layer and the floating oil film layer, and then obtain the Fresnel reflectivity of the s-wave and p-wave of the light source;

[0084] Calculation module V: Based on Snell's law of refraction, the relationship between the angle of refraction and the angle of incidence, as well as the relationship between the Fresnel reflectivity and the degree of polarization of s-waves and p-waves, are obtained, thereby obtaining the oil film refractive index corresponding to different wavelengths.

[0085] Example 1:

[0086] A specific example of calculating the refractive index of an oil film based on its degree of polarization includes the following steps:

[0087] S1: Acquire multiple polarization images of simulated diesel oil spills at the same light source with an incident angle of 30°;

[0088] S2: Preprocess multiple polarization images of oil spills on the sea surface;

[0089] S3: Using the polarization degree calculation method, based on the preprocessed polarization image of the oil spill on the sea surface, the average polarization degree of multiple images of the simulated oil slick on the sea surface is 1.6983.

[0090] S4: According to Snell's law of refraction formula (1), the relationship between the angle of refraction and the angle of incidence under this light source is obtained;

[0091] S5: Based on Maxwell's equations, the Fresnel reflection coefficient and transmission coefficient of s-wave and p-wave polarized light between the two medium surfaces of the air layer and the floating oil film layer are calculated and derived; the Fresnel reflection coefficient and transmission coefficient are obtained by formulas (2) and (3), respectively;

[0092] S6: Based on the Fresnel reflection coefficient and transmission coefficient between the two medium surfaces of the air layer and the floating oil film layer, and based on the oil film reflectance formula (4), the Fresnel reflectance of the s-wave and p-wave of the light source is obtained; the Fresnel reflectance of the s-wave and p-wave are obtained by formulas (5) and (6), respectively.

[0093] S7: Based on Snell's law of refraction, the relationship between the angle of refraction and the angle of incidence is obtained, as well as the relationship between the Fresnel reflectivity and the degree of polarization of s-waves and p-waves. The Fresnel reflectivity and the degree of polarization of s-waves and p-waves are obtained from formula (7) based on the relationship between the degrees of polarization. Thus, the refractive indices of the oil film corresponding to different wavelengths are obtained. Figure 3 .

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the refractive index of an oil film based on its degree of polarization, characterized in that: Includes the following steps: Acquire multiple polarization images of oil spills on the sea surface under the same light source and the same incident angle; Preprocessing of multiple polarization images of oil spills on the sea surface; The polarization degree of the simulated oil slick image on the sea surface was obtained by using the polarization degree calculation method based on the preprocessed polarization image of the oil spill on the sea surface. The angle of refraction of the light source is obtained according to Snell's law of refraction. and angle of incidence Relationship; The Fresnel reflection and transmission coefficients of S-wave and P-wave polarized light between the two medium surfaces of the air layer and the oil film layer were calculated and derived. The calculations derived the Fresnel reflection and transmission coefficients of S-wave and P-wave polarized light between the two dielectric surfaces of the air layer and the oil film layer as follows: in: It is the reflection coefficient of the S-wave. The reflection coefficient of the p-wave, The transmission coefficient of the p-wave; Based on the Fresnel reflection and transmission coefficients between the two medium surfaces of the air layer and the floating oil film layer, and based on the oil film reflectivity formula, the Fresnel reflectivity of the s-wave and p-wave of the light source is obtained. The Fresnel reflectance formulas for the s-wave and p-wave of the light source are as follows: in: It is the reflection coefficient of the S-wave on the surface of the oil film. It is the transmission coefficient of the S-wave on the upper surface of the oil film. It is the transmission coefficient of an S-wave as it passes through the air onto the upper surface of the oil film layer. It is the reflection coefficient of the P-wave on the upper surface of the oil film; It is the transmission coefficient of the P-wave on the upper surface of the oil film. The transmission coefficient of a P-wave as it passes through the upper surface of the oil film and into the air; i represents the imaginary part of the refractive index; a represents the extinction coefficient of the oil film; and s represents the optical path length of light within the oil film. kΔ represents the phase delay between the two beams of light. , , The measured oil film thickness, R is the wavelength of the incident light. s It is the S-wave reflectivity, R P It is P-wave reflectivity; It is the refractive index of the floating oil film; Based on the relationship between the Fresnel reflectivity and polarization degree of s-wave and p-wave, the refractive index of the oil film corresponding to different wavelengths can be obtained; The relationship between the Fresnel reflectivity of the S-wave and the P-wave and the degree of polarization P is as follows: Where: R s It is the S-wave reflectivity, R P It is P-wave reflectivity.

2. The method for calculating the refractive index of an oil film based on the degree of polarization of the oil film according to claim 1, characterized in that: The relationship between the angle of refraction and the angle of incidence is as follows: in: It is the refractive index of the air layer; It is the refractive index of the floating oil film; Angle of incidence; It is the angle of refraction.

3. A device for calculating the refractive index of an oil film based on its degree of polarization, characterized in that: include: Acquisition module: Used to acquire multiple polarization images of oil spills on the sea surface under the same light source and the same incident angle; Preprocessing module: Used to preprocess multiple polarization images of oil spills on the sea surface; Calculation Module I: Used to calculate the polarization degree of the simulated oil slick image on the sea surface based on the preprocessed polarization image of the oil spill on the sea surface using the polarization degree calculation method; Calculation Module II: Used to obtain the angle of refraction of the light source according to Snell's law of refraction. and angle of incidence Relationship; Calculation Module III: Used to calculate and derive the Fresnel reflection and transmission coefficients of S-wave and P-wave polarized light between the two medium surfaces of the air layer and the floating oil film layer; The calculations derived the Fresnel reflection and transmission coefficients of S-wave and P-wave polarized light between the two dielectric surfaces of the air layer and the oil film layer as follows: in: It is the reflection coefficient of the S-wave. The reflection coefficient of the p-wave, The transmission coefficient of the p-wave; Calculation Module IV: Used to obtain the Fresnel reflectance of the light source's s-wave and p-wave based on the Fresnel reflectance and transmission coefficients between the two medium surfaces of the air layer and the floating oil film layer, and the oil film reflectance formula; The Fresnel reflectance formulas for the s-wave and p-wave of the light source are as follows: in: It is the reflection coefficient of the S-wave on the surface of the oil film. It is the transmission coefficient of the S-wave on the upper surface of the oil film. It is the transmission coefficient of an S-wave as it passes through the air onto the upper surface of the oil film layer. It is the reflection coefficient of the P-wave on the upper surface of the oil film; It is the transmission coefficient of the P-wave on the upper surface of the oil film. The transmission coefficient of a P-wave as it passes through the upper surface of the oil film and into the air; i represents the imaginary part of the refractive index; a represents the extinction coefficient of the oil film; and s represents the optical path length of light within the oil film. kΔ represents the phase delay between the two beams of light. , , The measured oil film thickness, R is the wavelength of the incident light. s It is the S-wave reflectivity, R P It is P-wave reflectivity. It is the refractive index of the floating oil film; Calculation module V: Based on the relationship between the Fresnel reflectivity and polarization degree of s-wave and p-wave, the refractive index of the oil film corresponding to different wavelengths is obtained; The relationship between the Fresnel reflectivity of the S-wave and the P-wave and the degree of polarization P is as follows: Where: R s It is the S-wave reflectivity, R P It is P-wave reflectivity.

Images