CN112790753B - Three-dimensional laser Doppler blood flow instrument based on optical time division - Google Patents
Three-dimensional laser Doppler blood flow instrument based on optical time division Download PDFInfo
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- 230000017531 blood circulation Effects 0.000 title claims abstract description 35
- 230000003287 optical effect Effects 0.000 title claims abstract description 23
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- 210000000709 aorta Anatomy 0.000 abstract description 5
- 238000004364 calculation method Methods 0.000 description 10
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- 239000012530 fluid Substances 0.000 description 5
- 210000001367 artery Anatomy 0.000 description 3
- 239000003814 drug Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
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- 208000011775 arteriosclerosis disease Diseases 0.000 description 1
- 238000013475 authorization Methods 0.000 description 1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/026—Measuring blood flow
- A61B5/0261—Measuring blood flow using optical means, e.g. infrared light
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
- A61B5/7235—Details of waveform analysis
- A61B5/7253—Details of waveform analysis characterised by using transforms
- A61B5/7257—Details of waveform analysis characterised by using transforms using Fourier transforms
Abstract
The invention discloses a three-dimensional laser Doppler blood flow instrument based on optical time division, which comprises: the light source module converges light rays at a target point of the blood vessel to be detected from a plurality of angles in an optical time division mode; a receiving module for receiving the scattered light reflected from the target point; and the processing module is connected with the receiving module, obtains a plurality of Doppler frequency shift values through fast Fourier transform, and calculates the blood flow velocity by combining the obtained Doppler frequency shift values. The invention utilizes the Doppler effect of laser, uses the laser with the same wavelength to irradiate the target point of the aorta at a fixed time sequence, receives scattered light, obtains several different Doppler frequency shifts through fast Fourier transform analysis, and can accurately calculate the blood flow velocity by combining the obtained Doppler frequency shift values through fixing the spatial position relation between the emitted laser.
Description
Technical Field
The invention relates to the field of photoelectricity, in particular to a three-dimensional laser Doppler blood flow instrument based on optical time division.
Background
With the development of technology, people pay more attention to health, and to some extent, information on human blood flow includes many pieces of data on human health, and by measuring the flow velocity of blood, it is possible to assist diagnosis of valvular heart disease and congenital heart malformation caused by abnormalities such as reverse flow, stenotic flow, and short-circuit flow in blood vessels, or diagnosis of minor vascular stenosis, occlusion and determination of severity of disease in carotid arteries and limb arteries. Clinical research shows that the blood flow can directly reflect the physiological function of blood vessels and can be used as a measurement index for assisting clinical diagnosis. By detecting blood flow parameters, the blood circulation disorder and degree can be known, the heart function and arteriosclerosis can be judged, and the treatment effect and the medicine effect can be judged. It can be used as a measurement index for assisting clinical diagnosis.
Detection of blood flow has been widely used in medicine, and detection methods commonly used include isotopes, infrared imaging, ultrasonic doppler, laser doppler, and the like. Among them, the sensor based on the laser doppler technique is widely used without wound and with wide application range. The invention discloses an ultrasonic Doppler blood flow velocity measuring method demodulated by a single-channel multiplier, such as an authorization notice number CN 104758005B. But the accuracy is poor.
Disclosure of Invention
Aiming at the problem of poor measurement accuracy in the prior art, the invention provides an optical time division-based three-dimensional laser Doppler blood flow meter, which is based on the Doppler effect principle, utilizes a plurality of beams of laser with the same frequency in different directions to irradiate a target in a fixed time sequence by fixing the spatial relation of incident laser to obtain scattered light containing Doppler frequency shifts in different directions, and processes the received signals to obtain the flow velocity data of blood in a blood vessel in a three-dimensional space, thereby providing great help for clinical medicine.
The technical scheme of the invention is as follows.
An optical time division based three-dimensional laser doppler blood flow meter comprising:
the light source module converges light rays at a target point of the blood vessel to be detected from a plurality of angles in an optical time division mode;
the receiving module is used for receiving the scattered light reflected from the target point;
and the processing module is connected with the receiving module, obtains a plurality of Doppler frequency shift values through fast Fourier transform, and calculates the blood flow velocity by combining the obtained Doppler frequency shift values.
The invention utilizes the Doppler effect of laser, uses laser with different wavelengths to irradiate the target point of the aorta, receives scattered light, obtains several different Doppler frequency shifts through fast Fourier transform analysis, and can accurately calculate the blood flow velocity by combining the obtained Doppler frequency shift values through fixing the spatial position relation between the emitted laser.
Preferably, the light source module comprises a plurality of lasers, a spectroscope and a reflector, light emitted by the lasers is split by the spectroscope, one beam of light directly enters the target point, and the other beam of light enters the target point through the reflector. The tracks of the two light beams corresponding to the same laser are triangular, and the two light beams totally comprise a plurality of lasers.
As an alternative, the light source module includes several lasers, and the light emitted by the lasers is directly incident on the target point. Is a simplified version, and no spectroscope or reflector is used.
Preferably, the receiving module includes: the lens collects scattered light and then enters the detector.
Preferably, the plurality of lasers of the light source module emit laser with the same wavelength alternately in a set time at a fixed time sequence, and the laser is incident on the target point from a corresponding angle, and the rear laser is started when the previous laser is turned off. I.e., zero concatenation in time.
Preferably, among the three kinds of laser beams with different frequencies, an angle between the laser beam a and the laser beam B is 60 °, an included angle of a light beam projection viewed from directly above is 90 °, the laser beam C is interposed between the laser beam a and the laser beam B, and an included angle between the laser beam C and the other two laser beams viewed from directly above is 45 °. Selecting a particular angle may reduce the amount of computation.
Preferably, the processing module includes an amplifying circuit, an analog filter circuit, an AD conversion circuit, and an FFT module, the amplifying circuit amplifies the optical signal, the analog filter circuit filters the optical signal, the AD conversion circuit performs AD conversion, and the FFT module performs fourier transform on the data and calculates a doppler shift value and a blood flow velocity. After the structure of the invention is built, any required length or angle can be calculated by utilizing optical and geometric common sense, in addition, the data after primary processing is subjected to Fourier transform, and the blood flow velocity can be intuitively obtained after the Doppler frequency shift value is calculated.
The substantial effects of the invention include: the invention utilizes the Doppler effect of laser, uses the laser with the same wavelength to irradiate the target point of the aorta at a fixed time sequence, receives scattered light, obtains three different Doppler frequency shifts through fast Fourier transform analysis, and can accurately calculate the blood flow velocity by combining the obtained Doppler frequency shift values through fixing the spatial position relation between the emitted laser.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of the present invention;
FIG. 2 is a schematic diagram of a single laser incidence of an embodiment of the present invention;
FIG. 3 is a schematic diagram of a single laser beam path according to an embodiment of the present invention;
FIG. 4 is a side view of the optical path of a single laser according to an embodiment of the present invention;
FIG. 5 is a diagram illustrating the incident effect of three lasers according to an embodiment of the present invention;
FIG. 6 is a top view of the optical paths of three lasers according to an embodiment of the present invention;
FIG. 7 is another schematic structural diagram of an embodiment of the present invention;
FIG. 8 is a timing diagram of an embodiment of the present invention;
the drawing comprises the following steps: 1-laser, 2-spectroscope, 3-reflector, 4-lens, 5-detector.
Detailed Description
The technical solution of the present application will be described with reference to the following examples. In addition, numerous specific details are set forth below in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In some instances, methods, procedures, components, and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present invention.
Example 1:
fig. 1 shows a three-dimensional laser doppler blood flow meter based on optical time division, which includes:
the light source module converges light rays at a target point of a blood vessel to be detected from a plurality of angles in an optical time division mode, and comprises three lasers 1, a spectroscope 2 and a reflector 3, wherein light emitted by the lasers is split by the spectroscope as shown in figure 2, one beam of light directly enters the target point, and the other beam of light passes through the reflector and then enters the target point. Intensity 1 by spectroscope: 1, and one of the two laser beams split by the beam splitter enters the other laser beam at an angle of theta (for the sake of convenience, theta is 90 degrees later in calculation) after passing through the reflecting mirror, and the two laser beams are converged on flowing blood at the same time.
A receiving module that receives scattered light reflected from the target point, comprising: the lens 4 and the detector 5 are, as shown in fig. 3, such that the lens collects scattered light and then the scattered light is incident on the detector.
And the processing module is connected with the receiving module, obtains a plurality of Doppler frequency shift values through fast Fourier transform, and calculates the blood flow velocity by combining the obtained Doppler frequency shift values.
In the embodiment, the Doppler effect of laser is utilized, the laser with the same wavelength is used for irradiating the target point of the aorta in a fixed time sequence, scattered light is received, a plurality of different Doppler frequency shifts are obtained through fast Fourier transform analysis, and the blood flow velocity can be accurately calculated by combining the obtained Doppler frequency shift values through fixing the spatial position relation between the emitted laser.
As shown in fig. 4, the two light beams corresponding to the same laser have a triangular track, and collectively include a plurality of lasers, where A1, A2, and L1 all represent light beams or geometric line segments.
As shown in fig. 8, the plurality of lasers of the light source module alternately emit laser beams with the same wavelength at a fixed time sequence within a set time, and the laser beams are incident on the target point from corresponding angles, and the rear laser is activated when the previous laser is turned off. I.e., zero concatenation in time.
The light ray traces are shown in FIG. 5, where the symbols represent light rays, where A1 and A2 and B1 and B2 respectively have an included angle of 60 degrees, and C1 and C2 are located between A1, A2, B1 and B2. Wherein the included angles between A1 and A2, between B1 and B2, and between C1 and C2 are all 90 degrees. Fig. 6 is a top view, in three kinds of lasers with different frequencies, an angle between a laser a and a laser B is 60 °, an included angle of a light projection viewed from right above is 90 °, a laser C is between the laser a and the laser B, and an included angle between the laser C and the other two laser beams viewed from right above is 45 °. It can be seen that the plane formed by A1A2 is perpendicular to the plane formed by B1B2, while the plane formed by C1C2 is at an angle of 45 ° to the other two planes.
The processing module comprises an amplifying circuit, an analog filter circuit, an AD conversion circuit and an FFT module, wherein the amplifying circuit amplifies the optical signal, the analog filter circuit filters, the AD conversion circuit performs AD conversion, and the FFT module performs Fourier transformation on data and calculates Doppler frequency shift values and blood flow velocity. After the structure of this embodiment is built, utilize optics and geometry general knowledge can calculate any required length or angle, in addition carry out Fourier transform to the data after the preliminary processing, can directly perceived blood flow velocity after calculating the Doppler frequency shift numerical value.
According to the space coordinate relation in the schematic diagram, a more convenient calculation angle can be obtained by integrally rotating the A1, the A2, the B1, the B2, the C1 and the C2 and the fluid flow velocity vector, and ABC can be conveniently calculated by regarding the ABC as a line segment with the length of a without influencing the result of calculating the fluid velocity.
From this, it can be calculated that L1 has a length of
The calculation formula of Doppler shift can be obtained by a double-beam-double-scattering system:
f D ＝2vsin(θ/2)/λ；
it can be seen that the projection T of the intersection point of the vertex connecting lines of the line segments A1, A2, B1, B2, C1 and C2 is calculated by the doppler shift calculation formula, and the projection length of the vertex connecting line on the xoy plane to the y-axis is calculated, and the projection length and the vertex connecting line length are calculated
The ratio of (A) to (B) is the cosine of the angle between the fluid velocity and the line connecting the vertices of C1 and C2.
And the connection line of the vertexes B1 and B2 is vertical to the connection line of the vertexes A1 and A2.
The doppler shift formula generated by the B1 and B2 incident laser can be obtained by simple calculation:
wherein beta is an included angle between a plane formed by B1B2 and the blood flow direction. Assuming that the included angle between the A1 laser and the xoy plane is alpha, the included angle between the A2 laser and the xoy plane can be 90-alpha.
Therefore, the calculation formula of the laser Doppler frequency shift generated by the A1 and A2 lasers is calculated as follows:
the calculation formula of H can be derived according to the angle relation in the graph:
and the included angle theta between the vertex connecting line of C1 and C2 and the fluid speed 3 The cosine value calculation formula is as follows:
calculating the Doppler frequency shift by the following formula:
wherein f is D1 ，f D2 ，f D3 The value of (b) can be obtained by processing the received signal, and the wavelength λ is obtained from the properties of the laser and substituted.
From f D1 And f D2 Can deduce f D3 The unknowns in (a) are as follows:
substituting these six formulas into f D3 One univariate multiple function for v can be obtained:
V＝F(λ,f D1 ,f D2 ,f D3 )；
and calculating to obtain the magnitude value of the flow velocity of the blood fluid.
Specifically, the incident wavelength of the present embodiment is 630nm.
To get f D1 ＝1.5873*10 6 ；f D2 ＝1.25478*10 6 ；f D3 ＝2.16037*10 6 ；
By the calculation formula:
namely:
V＝F(λ,f D1 ,f D2 ,f D3 )；
the calculated blood flow rate was about 1m/s.
Example 2:
as an alternative, as shown in fig. 7, the light source module includes three lasers, light emitted from the lasers is directly incident on the target point, and the rest of the design is not changed. This is a simplified version and does not use a beam splitter or a mirror.
In the dual-beam-dual-scattering system, the beam splitter and the resulting split beam are discarded, allowing the three lasers to direct blood at the same fixed angles as above. I.e. the spectroscope and the A generated by the spectroscope are removed on the basis of the original scheme 2 ,B 2 ,C 2 And the incident laser light A 1 ,B 1 ,C 1 The spatial relationship between them is constant, the only change caused thereby being that the extreme value of the received photoelectric signal is 2f D Is changed into f D The magnitude of the Doppler shift itself is not changed, andthe above calculation formula can be referred to with respect to the new scheme without change.
The substantial effects of the present embodiment include: in the embodiment, the doppler effect of laser is utilized, laser with the same wavelength is used to irradiate the target point of the aorta at a fixed time sequence, scattered light is received, three different doppler shifts are obtained through fast fourier transform analysis, and the blood flow velocity can be accurately calculated by combining the obtained doppler shift values through fixing the spatial position relationship between the three emitted lasers. The influence of different trends of the human artery in a three-dimensional space and the angle of incident laser relative to the measured artery is overcome, and the accuracy and the use convenience of the Doppler blood flow velocimeter are greatly improved.
In the embodiments provided in the present application, it should be understood that units described as separate parts may or may not be physically separate, and parts displayed as units may be one physical unit or a plurality of physical units, that is, may be located in one place, or may be distributed in a plurality of different places. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (4)
1. A three-dimensional laser Doppler blood flow instrument based on optical time division is characterized by comprising:
the light source module converges light rays on a target point of a blood vessel to be measured from a plurality of angles in an optical time division mode;
the light source module comprises three lasers, a spectroscope and a reflector, light emitted by the lasers is split by the spectroscope, one beam of light directly enters a target point, the other beam of light enters the same target point through the reflector, and the incident included angle of the two beams of light is 90 degrees;
the three lasers of the light source module alternately emit laser with the same wavelength in a set time in a fixed time sequence, and respectively enter a target point from a corresponding angle, and the rear laser is started when the front laser is closed;
a receiving module for receiving the scattered light reflected from the target point;
the processing module is connected with the receiving module, obtains a plurality of Doppler frequency shift values through fast Fourier transform, and calculates by combining the obtained Doppler frequency shift values to obtain the blood flow velocity;
in the laser emitted by the three lasers, the angle between the laser A and the laser B is 60 degrees, the included angle of the projection of the light when the laser A is seen from right above is 90 degrees, the laser C is between the laser A and the laser B, and the included angle between the laser C and the other two beams of laser when the laser C is seen from right above is 45 degrees;
blood flow velocity is an expression for the values of laser wavelength and doppler shift: v = F (λ, F) D1 ,f D2 ,f D3 ) The method specifically comprises the following steps:
where λ is the wavelength of the laser, f D1 、f D2 And f D3 The frequency shift values produced by laser B, laser a, and laser C, respectively.
2. The optical time division based three-dimensional laser doppler blood flow meter according to claim 1, wherein the light source module comprises a plurality of lasers, and light emitted from the lasers is directly incident on the target point.
3. The optical time-division based three-dimensional laser doppler blood flow meter according to claim 1 or 2, wherein the receiving module comprises: the lens collects scattered light and then enters the detector.
4. The optical time division based three-dimensional laser doppler blood flow meter according to claim 1, wherein the processing module comprises an amplifying circuit, an analog filter circuit, an AD conversion circuit, and an FFT module, the amplifying circuit amplifies the optical signal, the analog filter circuit filters the optical signal, the AD conversion circuit performs AD conversion, and the FFT module performs fourier transform on the data and calculates doppler shift value and blood flow velocity.
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| US5620000A (en) * | 1993-07-02 | 1997-04-15 | Heidelberg Engineering, Optische Messsysteme Gmbh | Method and apparatus for measuring flow rate, particularly of blood |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5620000A (en) * | 1993-07-02 | 1997-04-15 | Heidelberg Engineering, Optische Messsysteme Gmbh | Method and apparatus for measuring flow rate, particularly of blood |
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