CN114947795A - Blood flow velocity detection method and detection device - Google Patents

Abstract

The invention discloses a method for detecting blood flow velocity, comprising: splitting a beam generated by a laser light source to form a first beam and a second beam; irradiating the first beam to a target to be measured to form scattered light; using an interferometric measurement method, Combine the scattered light and the second beam, and use the strong second beam to enhance the weak scattered light in the cross term of the interference signal; calculate the equivalent visibility factor of the speckle pattern; extract the decorrelation time from the equivalent visibility factor, and extract the target to be measured blood flow index. The invention can shorten the collection time of blood flow information, improve the sampling rate, has high sensitivity, and is suitable for blood flow index detection under the condition of weak scattering signal.

Description

A kind of detection method and detection device of blood flow velocity

technical field

The invention relates to the technical field of bio-optics, and in particular, to a detection method and a detection device for blood flow velocity.

Background technique

At present, the mainstream non-destructive optical monitoring methods of blood flow mainly include magnetic resonance imaging, transcranial Doppler, near-infrared light scattering and diffuse correlation spectroscopy. However, MRI equipment is expensive and cannot perform continuous measurements. Transcranial Doppler is the main instrument for clinical monitoring of cerebral hemodynamics. It is a semi-continuous method and mainly measures the blood flow of main blood vessels. Near-infrared light scattering methods have limited sensitivity for the small number of reflected photons in deep brain tissue. The diffuse correlation spectroscopy analysis method has long acquisition time and low sampling rate, and has poor effect on weak scattering signals.

SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, an aspect of the present invention provides a method for detecting blood flow velocity, including:

splitting the light beams generated by the laser light source to form a first light beam and a second light beam, and the light intensity of the second light beam is greater than that of the first light beam;

causing the first beam to illuminate the target to be measured to form scattered light;

combining the scattered light and the second light beam to form interference light;

Using the Fourier transform relationship, obtain complex field information of the cross interference term of the interference light from the interference light, and obtain the equivalent visibility factor of the speckle interference pattern of the interference light according to the complex field information;

According to the relationship between the equivalent visibility factor and the optical field decorrelation function of the interference light, obtain the optical field decorrelation time of the interference light from the equivalent visibility factor;

According to the optical field decorrelation time of the interference light and the correlation diffusion equation, the theoretical analysis and the actual measured optical field decorrelation function curve of the interference light are fitted to obtain the blood flow velocity of the target to be measured.

Preferably, causing the first beam to illuminate the target to be measured includes:

Coupling the first light beam into the light entrance end of the first optical fiber through the first lens;

The light-emitting end of the first optical fiber faces the target to be measured, so that the first light beam passing through the first optical fiber is irradiated on the target to be measured.

Preferably, splitting the light beam generated by the laser light source to form the first light beam and the second light beam includes: passing the light beam generated by the laser light source through the first half-wave plate and the beam splitter in sequence to form the first light beam and the second light beam. the second beam.

Preferably, a second half-wave plate, a second lens, a second optical fiber and a third lens are sequentially arranged on the optical path of the second light beam before combining.

Preferably, a fourth lens and a polarizer are sequentially arranged on the optical path of the scattered light before combining.

Preferably, combining the scattered light and the second light beam to form the interference light includes: passing the scattered light and the second light beam through a beam combiner to form the interference light.

In another aspect of the present invention, there is provided a blood flow velocity detection device, comprising:

Laser components for generating beams;

a beam splitting component for splitting the beam generated by the laser component into a first beam and a second beam;

a transmission component, connected to the beam splitting component, for transmitting the first light beam and irradiating the target to be measured to form scattered light;

a beam combining component for receiving the second light beam and the scattered light and combining them to form interference light;

a camera assembly for photographing the interference light to form a speckle interference pattern of the interference light;

an analysis component, using the Fourier transform relationship, to obtain complex field information of the cross interference term of the interference light from the interference light, and to obtain the equivalent of the speckle interference pattern of the interference light according to the complex field information visibility factor, and according to the relationship between the equivalent visibility factor and the optical field decorrelation function of the interference light, obtain the optical field decorrelation time of the interference light from the equivalent visibility factor, and then according to the The optical field decorrelation time and related diffusion equation of the interference light are fitted, and the theoretical analysis and the actual measured optical field decorrelation function curve of the interference light are fitted to obtain the blood flow velocity of the target to be measured.

Preferably, the beam splitting assembly includes a first half-wave plate and a beam splitter, and the first half-wave plate is disposed opposite to the light incident end of the beam splitter.

Preferably, the transmission component includes a first lens and a first optical fiber, one side of the first lens is arranged opposite to the light exit end of the first beam of the beam splitter, and the light entrance end of the first optical fiber is opposite to the light exit end of the first beam of the beam splitter. The other side of the first lens is oppositely arranged;

Wherein, the first light beam is coupled into the light input end of the first optical fiber through the first lens, and is irradiated on the target to be measured through the light output end of the first optical fiber.

Preferably, the beam combining component includes a beam combiner, and a second half-wave plate and a second lens are sequentially disposed on the opposite side of the light incident end of the second beam of the beam combiner along the incident light path of the second beam , a second optical fiber and a third lens, the opposite side of the incident light end of the scattered light of the beam combiner is sequentially provided with a fourth lens and a polarizer along the incident light program of the scattered light, and the camera assembly is arranged on the The opposite side of the light exit end of the beam combiner.

Compared with the prior art, in the present invention, blood flow-related information can be obtained in each frame of the captured image of the speckle interference pattern of the interference light, so the acquisition time of the blood flow velocity information can be shortened. Moreover, the present invention adopts the interferometric measurement method to enhance the weak signal light in the cross term of the interference signal, so it is suitable for the detection of blood flow velocity under the condition of weak scattered signal.

Description of drawings

FIG. 1 is a schematic structural diagram of a blood flow velocity detection device according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described with reference to the drawings are merely exemplary and the invention is not limited to these embodiments.

Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only the structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, and the related structures and/or processing steps are omitted. Other details not relevant to the invention.

In view of the prior art problems stated in the background section, the present invention provides the following specific embodiments.

Example 1

This embodiment provides a method for detecting blood flow velocity, and the detecting method includes:

Step S1, splitting the light beams generated by the laser light source to form a first light beam and a second light beam. Specifically, the light beams generated by the laser light source pass through the first half-wave plate and the beam splitter in sequence, so as to form the first light beam and the second light beam. Wherein, the light intensity of the second light beam is greater than the light intensity of the first light beam.

Step S2, irradiating the object to be measured with the first light beam to form scattered light. Specifically, the first light beam is coupled into the light input end of the first optical fiber through the first lens, and then the light output end of the first optical fiber faces the target to be measured, so that all the light passing through the first optical fiber is The first light beam is irradiated on the object to be measured. In this embodiment, the target to be measured is the head of the experimenter, the first light beam passes through the upper tissues such as the scalp and the skull to enter the cerebral cortex, and is scattered in the blood of the blood vessels of the cerebral cortex, and the formed scattered light Shoots outward through the layers of the skull and scalp.

Step S3, combining the scattered light and the second light beam to form interference light. Specifically, in this embodiment, the scattered light and the second light beam are passed through a beam combiner to form the interference light. Wherein, after the second light beam is formed, it passes through the second half-wave plate, the second lens, the second optical fiber and the third lens in sequence, and then enters a light entrance end of the beam combiner. After being formed, the scattered light passes through the fourth lens and the polarizer in sequence, and then enters the other light incident end of the beam combiner. In this embodiment, when collecting the scattered light, only the backscattered light formed by the first light beam in the blood vessels of the cerebral cortex is collected.

Step S4: Obtain complex field information of the cross interference term of the interference light from the interference light by using the Fourier transform relationship, and obtain the equivalent of the speckle interference pattern of the interference light according to the complex field information Visibility factor. Preferably, the speckle interference pattern of the interference light is captured by a camera.

Step S5 , obtaining the light field decorrelation time of the interference light from the equivalent visibility factor according to the relationship between the equivalent visibility factor and the light field decorrelation function of the interference light.

Step S6 , according to the optical field decorrelation time of the interference light and the correlation diffusion equation, fit the theoretical analysis and the actual measured optical field decorrelation function curve of the interference light to obtain the blood flow velocity of the target to be measured.

In this embodiment, blood flow-related information can be acquired in each frame of images of the captured speckle interference pattern of interference light, so the acquisition time of blood flow velocity information can be shortened. Moreover, the interferometric measurement method is adopted in this embodiment to enhance the weak signal light in the cross term of the interference signal, so it is suitable for blood flow velocity detection under the condition of weak scattered signal.

Example 2

Based on the method for detecting blood flow velocity in Embodiment 1, this embodiment provides a device for detecting blood flow velocity.

As shown in FIG. 1 , the blood flow velocity detection device of this embodiment includes:

Laser assembly 1 for generating a light beam.

The beam splitting component 2 is used for splitting the light beam generated by the laser component 1 into a first light beam and a second light beam. Wherein, the beam splitter assembly 2 includes a first half-wave plate 21 and a beam splitter 22 , and the first half-wave plate 21 is disposed opposite to the light incident end of the beam splitter 22 . After passing through the first half-wave plate 21 , the light beam generated by the laser assembly 1 is incident on the light entrance end of the beam splitter 22 .

The transmission component 3, connected with the beam splitting component 2, is used for transmitting the first light beam and irradiating it on the target A to be measured to form scattered light. Wherein, the transmission component 3 includes a first lens 31 and a first optical fiber 32, one side of the first lens 31 is disposed opposite to the light exit end of the first beam of the beam splitter 22, and the first optical fiber 32 The light incident end of the first lens 31 is opposite to the other side of the first lens 31 . The first light beam is coupled into the light input end of the first optical fiber 32 through the first lens 31 , and is irradiated on the target A to be measured through the light output end of the first optical fiber 32 .

The beam combining component 4 is used to receive the second light beam and the scattered light and combine them to form interference light. Wherein, the beam combining assembly 4 includes a beam combiner 41 . A second half-wave plate 42 , a second lens 43 , a second optical fiber 44 and a third lens 45 are sequentially disposed on the opposite side of the light incident end of the second light beam of the beam combiner 41 along the incident light program of the second light beam . A fourth lens 46 and a polarizer 47 are sequentially disposed on the opposite side of the light incident end of the scattered light of the beam combiner 41 along the incident light procedure of the scattered light.

The camera assembly 5 is used for photographing the interference light to form a speckle interference pattern of the interference light. Wherein, the camera assembly 5 is disposed on the opposite side of the light-emitting end of the beam combiner 41 .

The analysis component (not shown in the figure) uses the Fourier transform relationship to obtain the complex field information of the cross interference term of the interference light from the interference light, and obtains the complex field information of the interference light according to the complex field information. The equivalent visibility factor of the speckle interference pattern, and according to the relationship between the equivalent visibility factor and the optical field decorrelation function of the interference light, the optical field of the interference light is obtained from the equivalent visibility factor The decorrelation time, then according to the light field decorrelation time of the interference light and the related diffusion equation, fit the theoretical analysis and the actual measured light field decorrelation function curve of the interference light to obtain the blood flow of the target to be measured. flow rate.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. A method for detecting a blood flow velocity, comprising:

splitting a light beam generated by a laser light source to form a first light beam and a second light beam, wherein the light intensity of the second light beam is greater than that of the first light beam;

irradiating the target to be detected by the first light beam to form scattered light;

combining the scattered light and the second light beam to form interference light;

obtaining complex field information of a cross interference item of the interference light from the interference light by utilizing a Fourier transform relation, and obtaining an equivalent visibility factor of a speckle interference pattern of the interference light according to the complex field information;

acquiring the light field decorrelation time of the interference light from the equivalent visibility factor according to the relation between the equivalent visibility factor and the light field decorrelation function of the interference light;

and fitting a theoretical analysis and actually measured light field decorrelation function curve of the interference light according to the light field decorrelation time and the correlation diffusion equation of the interference light to obtain the blood flow velocity of the target to be measured.

2. The method for detecting blood flow velocity according to claim 1, wherein the irradiating the target to be measured with the first light beam includes:

coupling the first light beam into the light input end of a first optical fiber through a first lens;

and enabling the light outlet end of the first optical fiber to face the target to be measured, so that the first light beam passing through the first optical fiber is irradiated on the target to be measured.

3. The method for detecting blood flow velocity according to claim 1 or 2, wherein splitting the light beam generated by the laser light source to form the first light beam and the second light beam comprises: and enabling the light beam generated by the laser light source to sequentially pass through a first half-wave plate and a beam splitter to form the first light beam and the second light beam.

4. The method according to claim 3, wherein a second half-wave plate, a second lens, a second optical fiber and a third lens are sequentially disposed on the optical path of the second light beam before beam combination.

5. The method of claim 4, wherein a fourth lens and a polarizing plate are sequentially disposed on an optical path of the scattered light before the combination.

6. The method of claim 3, wherein the combining the scattered light and the second light beam to form interference light comprises: and enabling the scattered light and the second light beam to pass through a beam combiner to form the interference light.

7. A device for detecting a flow rate of a blood flow, comprising:

a laser assembly for generating a beam of light;

the beam splitting assembly is used for splitting the light beam generated by the laser assembly into a first light beam and a second light beam, and the light intensity of the second light beam is greater than that of the first light beam;

the transmission assembly is connected with the beam splitting assembly and used for transmitting the first light beam and irradiating the first light beam on a target to be detected to form scattered light;

the beam combining component is used for receiving the second light beam and the scattered light and combining the beams to form interference light;

the camera assembly is used for shooting the interference light to form a speckle interference pattern of the interference light;

and the analysis component is used for obtaining complex field information of a cross interference item of the interference light from the interference light by utilizing a Fourier transform relation, obtaining an equivalent visibility factor of a speckle interference pattern of the interference light according to the complex field information, obtaining a light field decorrelation time of the interference light from the equivalent visibility factor according to the relation between the equivalent visibility factor and a light field decorrelation function of the interference light, and fitting a light field decorrelation function curve of the interference light which is theoretically analyzed and actually measured according to the light field decorrelation time of the interference light and a correlation diffusion equation to obtain the blood flow velocity of the target to be measured.

8. The apparatus of claim 7, wherein the beam splitting assembly comprises a first half wave plate and a beam splitter, and the first half wave plate is disposed opposite to the light-entering end of the beam splitter.

9. The apparatus according to claim 8, wherein the transmission assembly comprises a first lens and a first optical fiber, one side of the first lens is disposed opposite to the light-emitting end of the first light beam of the beam splitter, and the light-entering end of the first optical fiber is disposed opposite to the other side of the first lens;

the first light beam is coupled into the light input end of the first optical fiber through the first lens and irradiates the target to be measured through the light output end of the first optical fiber.

10. The apparatus according to claim 9, wherein the beam combiner comprises a beam combiner, a second half-wave plate, a second lens, a second optical fiber and a third lens are sequentially disposed on an opposite side of an incident end of the second light beam of the beam combiner along an incident optical path of the second light beam, a fourth lens and a polarizer are sequentially disposed on an opposite side of an incident end of the scattered light of the beam combiner along an incident optical path of the scattered light, and the camera assembly is disposed on an opposite side of an exit end of the beam combiner.

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