A method and device for measuring the intensity distribution of random medium scattering potential

Abstract

The present invention discloses a method and device for measuring the scattering potential intensity distribution of a random medium. The method comprises the steps of collecting the scattered light intensity at a specific incident light angle, collecting the scattered light intensity at multiple incident light angles, and calculating the scattering potential intensity distribution. The device comprises a laser light source, a beam expansion and collimation system, a light intensity detector, and a full solid angle rotation mechanism. The method and device for measuring the scattering potential intensity distribution of a random medium of the present invention have the characteristics of strong realization, convenient testing, and high accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of optical scattering imaging, and in particular to a method and a device for measuring the intensity distribution of random medium scattering potential. Background Art

[0002] Biological tissues, human tissues, and other transparent or translucent materials generally have the characteristic of uneven distribution of refractive index with spatial position. At the same time, this refractive index distribution is generally unknown in advance, so it is called random medium in optics. The optical properties and structural information of this type of medium are completely contained in the refractive index distribution function, that is, contained in the scattering potential function. If some means can be used to obtain the information of the scattering potential, the imaging of the medium is completed. Using electromagnetic waves as a medium, the information of the scattering potential can be obtained contactlessly. This type of method uses sound waves, microwaves, and X-rays to realize practical imaging technology. However, the resolution of sound waves is limited by the wavelength scale, and X-rays have potential damage to tissues. Electromagnetic waves with wavelengths near visible light can overcome the difficulties of insufficient resolution and low safety.

[0003] Moreover, the above optical imaging methods generally need to obtain the complex amplitude information of the scattered field generated after the interaction between light and the medium, which requires the use of complex and time-consuming interference technology as a basis. Summary of the invention

[0004] The purpose of the present invention is to provide a method and a device for measuring the intensity distribution of the scattering potential of a random medium, which have the characteristics of strong realization, convenient testing and high accuracy.

[0005] The present invention can be implemented by the following technical solutions:

[0006] The present invention discloses a method for measuring the scattering potential intensity distribution of a random medium, comprising the following steps:

[0007] S1. Collection of scattered light intensity at a specific incident light angle: The laser light source emits a light beam covering the scattering sample to be measured. After being scattered by the scattering sample, the light beam forms scattered light fields at various angles in different directions. The scattered light intensity at each angle is collected respectively to complete the collection of scattered light intensity at a specific incident light angle.

[0008] S2. Collection of scattered light intensity of incident light at multiple angles: changing the incident light angle, repeating the collection process of scattered light intensity at a specific incident light angle in step S1, and completing the collection of scattered light intensity of incident light at different incident angles;

[0009] S3, scattering potential intensity distribution calculation, combined with the data collected from the scattered light intensity of multi-angle incident light in step S2, calculate the correlation between the average light intensity and the light intensity fluctuation, and determine the random medium scattering potential intensity distribution.

[0010] Furthermore, in the collection of scattered light intensity at a specific incident light angle in step S1, the laser light emitted by the laser light source is collimated and expanded into a light beam having an area that can cover the scattered sample to be measured.

[0011] Furthermore, in the step S1 of collecting scattered light intensity at a specific incident light angle, the light intensity detector collects scattered light intensity at various angles driven by the full solid angle rotation mechanism.

[0012] Furthermore, in step S2 of collecting the scattered light intensity of incident light at multiple angles, the laser light source and the beam expansion and collimation system complete the collection of the scattered light intensity of incident light at different incident angles under the drive of the continuously rotatable mechanism (6).

[0013] Furthermore, the average value of the detected light intensity at different incident angles is an approximation of the ensemble average value of different realizations of the scattering medium. The average value is:

[0014]

[0015] In the formula, <·> i represents the average in the set of incident angle measurements, <·> e represents the ensemble average, is the average light intensity.

[0016] Furthermore, the calculation method of the scattering potential intensity distribution S(r) is:

[0017] Assume that the distance between the light intensity detector and the origin of the selected coordinate system is r, and the light intensity at the angle determined by the unit vector u is I(ru), thus defining the correlation function of measuring light intensity fluctuations at two different angles u1 and u2:

[0018]

[0019] For incident light with a wavelength of λ and an angular frequency of ω, assuming that the dielectric constant distribution of the medium is ∈(r), the scattering potential function of the medium is F(r) = k 2 (∈(r)-1), and its scattering potential intensity is defined as:

[0020] S(r)= <F * (r)F(r)>

[0021] Where k = 2 / λ is the wave number of the incident light;

[0022] The scattering theory under the first-order Born approximation gives the relationship between the scattered light intensity correlation and the medium scattering potential intensity as follows:

[0023]

[0024] in is the three-dimensional Fourier transform of S;

[0025] By using the light intensity data measured by the light intensity detector in different directions and according to the above formula, the absolute value part of the Fourier spectrum of the scattering potential intensity distribution can be obtained;

[0026] Then, using the phase recovery algorithm, we can find The phase part of Complete information of

[0027] right By performing Fourier transform, the scattering potential intensity distribution S(r) can be obtained.

[0028] Another aspect of the present invention is to protect a measuring device that uses the above-mentioned method for measuring the random medium scattering potential intensity distribution, including a laser light source, a beam expansion and collimation system, a light intensity detector and a full solid angle rotation mechanism; the laser emitted by the laser light source is collimated by the beam expansion and collimation system and expanded into a light beam with an area that can cover the scattering sample to be measured; the light beam is scattered by the scattering sample to form a scattered light field in all directions; the light intensity detector is driven by the full solid angle rotation mechanism to collect the scattered light intensity at each angle in turn.

[0029] Furthermore, the measuring device also includes a continuously rotatable mechanism, and the laser light source and the beam expansion and collimation system are driven by the continuously rotatable mechanism to change the angle of incident light and collect the scattered light intensity of multi-angle incident light.

[0030] Furthermore, the laser light source is a continuous laser.

[0031] The present invention provides a method and device for measuring the scattering potential intensity distribution of a random medium, which has the following beneficial effects:

[0032] First, the feasibility is strong. The optical path of the present invention is simple to build, the number of measuring optical path components is small, the structure is compact, and it has strong feasibility;

[0033] Second, the data collection is convenient. The present invention does not need to collect the complex amplitude information of the scattered light field, but only needs the light intensity detector to obtain the light intensity information. This effectively simplifies the operation of the data collection process and avoids the measurement errors caused by too many parameter collections.

[0034] Third, the accuracy is high. The present invention uses the acquired light intensity information combined with the relatively mature phase recovery technology to reconstruct the scattering potential intensity distribution function, realizes the combination of the scattered far-field light intensity fluctuation information and the scattering potential intensity distribution, and improves its accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Attached Figure 1 A flow chart of a method for measuring the scattering potential intensity distribution of a random medium according to the present invention;

[0036] Attached Figure 2 A schematic diagram of the composition of a random medium scattering potential intensity distribution measuring device according to the present invention;

[0037] The symbols in the accompanying drawings include: a laser light source 1, a beam expansion and collimation system 2, a scattering sample to be measured 3, a light intensity detector 4, a full solid angle rotation mechanism 5, and a continuously rotatable mechanism 6. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention is further described in detail below in conjunction with embodiments and drawings.

[0039] like Figure 1 As shown, the present invention discloses a method for measuring the scattering potential intensity distribution of a random medium, comprising the following steps:

[0040] S1. Collection of scattered light intensity at a specific incident light angle: The laser light source emits a light beam covering the scattering sample to be measured. After being scattered by the scattering sample, the light beam forms scattered light fields at various angles in different directions. The scattered light intensity at each angle is collected respectively to complete the collection of scattered light intensity at a specific incident light angle.

[0041] S2. Collection of scattered light intensity of incident light at multiple angles: changing the incident light angle, repeating the collection process of scattered light intensity at a specific incident light angle in step S1, and completing the collection of scattered light intensity of incident light at different incident angles;

[0042] S3, scattering potential intensity distribution calculation, combined with the data collected from the scattered light intensity of multi-angle incident light in step S2, calculate the correlation between the average light intensity and the light intensity fluctuation, and determine the random medium scattering potential intensity distribution.

[0043] Furthermore, in the collection of scattered light intensity at a specific incident light angle in step S1, the laser light emitted by the laser light source is collimated and expanded into a light beam having an area that can cover the scattered sample to be measured.

[0044] Furthermore, in the step S1 of collecting scattered light intensity at a specific incident light angle, the light intensity detector collects scattered light intensity at various angles driven by the full solid angle rotation mechanism.

[0045] Furthermore, in step S2 of collecting the scattered light intensity of incident light at multiple angles, the laser light source and the beam expansion and collimation system complete the collection of the scattered light intensity of incident light at different incident angles under the drive of the continuously rotatable mechanism (6).

[0046] Furthermore, the average value of the detected light intensity at different incident angles is an approximation of the ensemble average value of different realizations of the scattering medium. The average value is:

[0047]

[0048] In the formula, <·> i denotes averaging over the set of incident angle measurements, <·> e represents the ensemble average, is the average light intensity.

[0049] Furthermore, the calculation method of the scattering potential intensity distribution S(r) is:

[0050] Assume that the distance between the light intensity detector and the origin of the selected coordinate system is r, and the light intensity at the angle determined by the unit vector u is I(ru), thus defining the correlation function of measuring light intensity fluctuations at two different angles u1 and u2:

[0051]

[0052] For incident light with a wavelength of λ and an angular frequency of ω, assuming that the dielectric constant distribution of the medium is ∈(r), the scattering potential function of the medium is F(r) = k 2 (∈(r)-1), and its scattering potential intensity is defined as:

[0053] S(r)= <F * (r)F(r)>

[0054] Where k = 2π / λ is the wave number of the incident light;

[0055] The scattering theory under the first-order Born approximation gives the relationship between the scattered light intensity correlation and the medium scattering potential intensity as follows:

[0056]

[0057] in is the three-dimensional Fourier transform of S;

[0058] By using the light intensity data measured by the light intensity detector in different directions and according to the above formula, the absolute value part of the Fourier spectrum of the scattering potential intensity distribution can be obtained;

[0059] Then, using the phase recovery algorithm, we can find The phase part of Complete information of

[0060] right By performing Fourier transform, the scattering potential intensity distribution S(r) can be obtained.

[0061] like Figure 2As shown, another aspect of the present invention is to protect a measuring device using the above-mentioned random medium scattering potential intensity distribution measurement method, including a laser light source 1, a beam expansion and collimation system 2, a light intensity detector 4 and a full solid angle rotation mechanism 5; the laser emitted by the laser light source 1 is collimated by the beam expansion and collimation system 2 and expanded into a light beam with an area that can cover the scattering sample 3 to be measured; the light beam is scattered by the scattering sample 3 to form a scattered light field in all directions; the light intensity detector 4 is driven by the full solid angle rotation mechanism 5 to collect the scattered light intensity at each angle in turn.

[0062] like Figure 2 As shown, the measuring device also includes a continuously rotatable mechanism 6. Driven by the continuously rotatable mechanism 6, the laser light source 1 and the beam expansion and collimation system 2 change the incident light angle to collect the scattered light intensity of the incident light at multiple angles.

[0063] Specifically, the laser light source is a continuous laser.

[0064] The above embodiments are only specific embodiments of the present invention, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and these obvious replacement forms all belong to the protection scope of the present invention.

Claims

1. A method for measuring the scattering potential intensity distribution of a random medium, characterized in that The following steps are involved: S1. Collection of scattered light intensity at a specific incident light angle: The laser light source emits a light beam covering the scattering sample to be measured. After being scattered by the scattering sample, the light beam forms scattered light fields at various angles in different directions. The scattered light intensity at each angle is collected respectively to complete the collection of scattered light intensity at a specific incident light angle. S2. Collection of scattered light intensity of incident light at multiple angles: changing the incident light angle, repeating the collection process of scattered light intensity at a specific incident light angle in step S1, and completing the collection of scattered light intensity of incident light at different incident angles; S3, calculation of scattering potential intensity distribution: combining the data obtained from the collection of scattered light intensity of incident light at multiple angles in step S2, calculating the correlation between the average light intensity and the light intensity fluctuation, and determining the scattering potential intensity distribution of the random medium; The average value of the detected light intensity at different incident angles is the approximate value of the ensemble average value of different realizations of the scattering medium, which is: , where represents the average in the set of incident angle measurements, represents the ensemble average, is the average value of light intensity; Scattering potential intensity distribution The calculation method is: Assume that the distance between the light intensity detector and the origin of the selected coordinate system is , in the unit vector The light intensity at a certain angle is , which is defined at two different angles and The correlation function of the measured light intensity fluctuations is: , for wavelength , the angular frequency is The incident light, assuming the dielectric constant distribution of the medium is , then the scattering potential function of the medium is , and its scattering potential intensity is defined as: ； in is the wave number of the incident light; The scattering theory under the first-order Born approximation gives the relationship between the scattered light intensity correlation and the medium scattering potential intensity as follows: ； in for The three-dimensional Fourier transform of By using the light intensity data measured by the light intensity detector in different directions and according to the above formula, the absolute value part of the Fourier spectrum of the scattering potential intensity distribution can be obtained; Then, using the phase recovery algorithm, we can find The phase part of Complete information of right Perform Fourier transform to get the scattering potential intensity distribution .

2. The method for measuring the scattering potential intensity distribution of random media according to claim 1, characterized in that: In step S1 of collecting scattered light intensity at a specific incident light angle, the laser light emitted by the laser light source is collimated and expanded into a light beam whose area can cover the scattered sample to be measured.

3. The method for measuring the scattering potential intensity distribution of random media according to claim 1, characterized in that: In step S1 of collecting scattered light intensity at a specific incident light angle, the light intensity detector collects scattered light intensity at various angles driven by the full solid angle rotation mechanism.

4. The method for measuring the scattering potential intensity distribution of random media according to claim 1, characterized in that: In step S2 of collecting scattered light intensity of incident light at multiple angles, the laser light source and the beam expansion and collimation system complete the collection of scattered light intensity of incident light at different incident angles under the drive of the continuously rotatable mechanism (6).

5. A measuring device using the method for measuring the random medium scattering potential intensity distribution according to any one of claims 1 to 4, characterized in that: It includes laser light source, beam expansion and collimation system, light intensity detector and full solid angle rotation mechanism; The laser light emitted by the laser light source is collimated by the beam expansion and collimation system and expanded into a light beam whose area can cover the scattering sample to be measured; The light beam is scattered by the scattering sample to form a scattered light field in all directions; Driven by the full solid angle rotating mechanism, the light intensity detector collects scattered light intensity at various angles in turn.

6. The device for measuring the scattering potential intensity distribution of random media according to claim 5, characterized in that: The measuring device also includes a continuously rotatable mechanism. The laser light source and the beam expansion and collimation system are driven by the continuously rotatable mechanism to change the incident light angle and collect the scattered light intensity of the incident light at multiple angles.

7. The device for measuring the scattering potential intensity distribution of random media according to claim 5, characterized in that: The laser light source is a continuous laser.

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