CN101251514B - Dorsal mode light acoustic imaging method based on multiple phase control focusing ring array - Google Patents
Dorsal mode light acoustic imaging method based on multiple phase control focusing ring array Download PDFInfo
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- CN101251514B CN101251514B CN 200810030972 CN200810030972A CN101251514B CN 101251514 B CN101251514 B CN 101251514B CN 200810030972 CN200810030972 CN 200810030972 CN 200810030972 A CN200810030972 A CN 200810030972A CN 101251514 B CN101251514 B CN 101251514B
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Abstract
The invention provides a multiple phase control focus ring array-based dorsad mode optical acoustic imaging method; steps of the method are as follows: (1) the pulsed laser is used to irradiate a sample to be tested; (2) the sample to be tested or a multi-ring array detector receives optical acoustic signals by the dorsad mode of a step motor driving scan, and simultaneously acquires the data of optical acoustic signals; (3) data processing software is used to calculate the phase control of the acquired optical acoustic signals for realizing the dynamic focus mode A scan in the depth Z direction, and by the two-dimensional data scanning in the X-Y direction of the step motor point-to-point, a three-dimensional optical absorption distribution map can be synthesized by the back projection. The method has the advantages that due to the adoption of the multi-ring array detector, the super narrow aperture angle and the good direction pointing of the multi-ring array detector greatly improve the imaging resolution, and realize the focus scan imaging in both X and Y directions; due to the adoption of the calculation phase control focus technology, the signal to noise ratio of signals can be effectively improved, and the mode A dynamic focus scan imaging in the depth Z direction can be realized; due to the receiving of optical acoustic signals in the dorsad mode, the operability and the application range of the system are greatly improved.
Description
Technical field
The present invention relates to a kind of thermometrically and formation method, be specifically related to a kind of dorsal mode light acoustic imaging method based on multiple phase control focusing ring array.
Background technology
At present the measurement pattern of photoacoustic imaging has forward direction, side direction and three kinds of patterns dorsad:
Because the high scattering of bio-tissue, the scope of application of forward mode system is very little.
The lateral mode system adopts modes such as detector rotation sweep, sample rotation sweep, planar linear scanning to obtain the distribution that optoacoustic is pressed in certain plane usually, again by the counter light absorption distributed image of releasing the space of specific reconstruction algorithm.This mode has very high spatial resolution, but its time resolution is lower, imaging algorithm is complicated, spatial directivity is poor, and because the feature limits of biosome, this scan mode usually can't be practical.
In actual applications, for the ease of the operation diagnosis, system detector and excitation source place the same side of biosome usually, and this measurement pattern is called pattern dorsad.The detector of this pattern employing has high frequency focus detector, piezoceramic disk film explorer and dicyclo detector at present.Wide-aperture high frequency focus detector can obtain good signal to noise ratio (S/N ratio), but it focuses on focal spot and burnt length limits its imaging resolution and imaging visual angle, and the rapid decay of signal in tissue also limited its investigation depth; The piezoceramic disk film explorer has very high temporal resolution, and the longitudinal frame of three-dimensional imaging can reach tens of microns, but its directivity and poor signal to noise; The dicyclo detector has narrower aperture angle and certain direction directive property, but its less aperture makes the signal to noise ratio (S/N ratio) of collection relatively poor, and can't realize the dynamic focusing of depth direction.
Summary of the invention
The object of the present invention is to provide a kind ofly for solving the aforementioned problems in the prior, the invention provides a kind of dorsal mode light acoustic imaging method based on multiple phase control focusing ring array, this method may further comprise the steps:
(1) adopt pulse laser to incide on the testing sample, the excitation testing sample produces photoacoustic signal;
(2) testing sample or polynary ring detector array scan pattern reception photoacoustic signal dorsad by step motor drive, gather the photoacoustic signal data simultaneously;
(3) application data process software dynamic focusing a-scan that the photoacoustic signal of gathering is calculated phased realization degree of depth Z direction, the data of utilizing the two-dimensional scan of the point-to-point X-Y direction of stepper motor to gather again can the synthetic three-dimensional light absorption distributed image of back projection.
The wavelength coverage of pulse laser is 400nm～2500nm described in the step (1).
Described polynary ring detector array described in the step (2) is a homalographic, equidistant and hollow, and its central authorities are coupled with optical fiber head, and the number of detector rings is no less than two.
Scanning described in the step (2) and collection are under software program control, scan type collection photoacoustic signal dorsad by stepper motor drive detector of sound or testing sample, and wherein the plane of a loop and the plane of scanning motion are same plane.
It is to adopt the method for parallel or serial to gather photoacoustic signal that polynary ring array detector of sound described in the step (2) receives photoacoustic signal.
The present invention also provides a kind of device of realizing said method, comprises laser generating assembly, step-scan assembly, photoacoustic signal acquisition component, acoustic coupling assembly, sample fixation kit, computing machine; Laser generating assembly, photoacoustic signal acquisition component, computing machine are electrically connected successively; Step-scan assembly and computing machine are electrically connected; Sample fixation kit and step-scan assembly are electrically connected.
Described laser generating assembly is formed by connecting by laser instrument and optical fiber, and wherein optical fiber head is coupled in the polynary ring detector array central authorities of hollow;
Described photoacoustic signal acquisition component is electrically connected successively by polynary ring detector array, data pretreating device and data collector and constitutes, and wherein polynary ring detector array is equidistant homalographic, and is fixed on the 3-D scanning platform by support; The data pretreating device comprises the circuit of functions such as impedance matching, signal amplification, signal filtering; Data collector adopts high-speed data acquisition card or oscillograph;
Described step-scan assembly can be electrically connected and be formed by relay, stepper motor, 3-D scanning platform; Polynary ring detector array and stepper motor are electrically connected, and stepper motor and 3-D scanning platform are electrically connected, and stepper motor also is electrically connected with relay, and relay is connected with computing machine by digital I/O card;
Described sample fixation kit is made up of three-dimensional adjustable sample stage and sample stationary installation;
Described acoustic coupling assembly is made up of sample cell harmony coupling liquid.
Advantage of the present invention is: the dorsal mode light acoustic imaging method that utilizes multiple phase control focusing ring array that the present invention proposes, owing to adopt polynary ring detector array, its super narrow aperture angle and good direction directive property have improved imaging resolution greatly, all can realize the focusing scanning imaging at X and Y direction; Adopt and calculate the phase-control focusing technology, can effectively improve the signal to noise ratio (S/N ratio) of signal, can realize the A type dynamic focusing scanning imagery of degree of depth Z direction; Adopt pattern reception photoacoustic signal dorsad, can greatly improve the operability and the scope of application of system.
Description of drawings
Fig. 1 is the structural representation of embodiment 1 described device.
Fig. 2 utilizes to calculate the a-scan schematic diagram that phase-control focusing is realized degree of depth Z direction.
Fig. 3 utilizes the device of embodiment 1 to being embedded with the image that agar became of three carbon-points.
Embodiment
Fig. 1 is the structure drawing of device of present embodiment, and the name of each element shown in the figure is called: laser generator 1-1, optical fiber 1-2,3-D scanning platform 2-1, step actuator 2-2, digital I/O control card 2-3, polynary ring detector array 3-1, signal preprocessor 3-2, digital oscilloscope 3-3, gpib bus communication card 3-4, computing machine 4, sample stage 5, sample cell 6-1, acoustic coupling liquid 6-2.Apparatus of the present invention are made up of laser generating assembly, step-scan assembly, photoacoustic signal acquisition component, acoustic coupling assembly, sample fixation kit, computing machine etc.Wherein the laser generating assembly is connected and composed by laser instrument 1-1 and optical fiber 1-2; The step-scan assembly moves polynary ring detector array 3-1 and sample stage 5 by computing machine 4 by digital I/O control card 2-3 and step actuator 2-2 control 3-D scanning platform 2-1; The photoacoustic signal acquisition component receives photoacoustic signal by polynary ring detector array 3-1, after pre-service such as signal preprocessor 3-2 amplification, multichannel selection, filtering, be transferred to computing machine 4 by digital oscilloscope 3-3 collection through gpib bus communication card 3-4, computing machine 4 sends gating code by digital I/O control card 2-3 and selects the two-way in the multiple signals to enter digital oscilloscope 3-3 collection, the synchronization output signal triggered digital oscillograph 3-3 acquired signal of laser instrument 1-1, wherein acoustical signal is coupled to polynary ring detector array 3-1 by acoustic coupling liquid 6-2.Wherein: laser instrument 1-1 be the Nd:YAG solid state laser (BrilliantB, Bigsky), operation wavelength is 1064nm, pulsewidth is 8ns, and single pulse energy reaches 40mJ, and laser energy is radiated on the sample by optical fiber 1-2 uniformly, wherein fibre diameter D is about 0.6mm, and numerical aperture NA is 0.22; Be placed on the plastic sample platform 5 by the sample of imaging, sample cell 6-1 is the cuboid container made from synthetic resin, has been full of acoustic coupling liquid 6-2 water conservancy in the sample cell and has mated in the velocity of sound.
It is the octatomic ring detector array 5A8E20 of 5MHz that polynary ring detector array 3-1 selects centre frequency, and table 1 is that centre frequency is the octatomic ring array detector of sound 5A8E20 dimensional parameters of 5MHz.
Table 1
| The sequence number of |
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Internal diameter (mm) | 3 | 4.24 | 5.22 | 6.07 | 6.83 | 7.52 | 8.17 | 8.78 |
| External diameter (mm) | 4.09 | 5.07 | 5.92 | 6.68 | 7.38 | 8.02 | 8.63 | 9.21 |
It is equidistant that each ring is designed to homalographic, and wherein the interannular spacing is a half-wavelength.Select 2 articulatings to receive photoacoustic signals by MUX at every turn, the signal of reception by pre-service such as preposition amplification, filtering after, confession digital oscilloscope 3-3 gathers into computing machine 4; At the next pulse of clock signal, computing machine 4 sends gating code and enters the reception of dicyclo signal next time, and per 4 pulses are a clock period to have gathered the signal of a position.Select 8 rings to do at every turn and calculate the phase-control focusing processing, in fact equivalence is a detector that has very strong spatial directivity to point to, and on its relevant focusing Z-direction, each detector receives identical owing to phase place is compensated, the synthetic signal maximum of signal; On the non-focusing direction of detector, the compensation of the signal phase of each detector is different, and signal cancels each other out.Wherein phase differential is the propagation time difference that focus point arrives each interannular, and principle as shown in Figure 2.Conversion of signals with each position sensor collection during imaging becomes the one dimension image, the one dimension images is scanned in a plurality of positions of X-Y plane make up also back projection's one-tenth 3-D view in order, realizes the light absorption distribution three-dimensional imaging of object easily and fast.
Embodiment 2 the preferred method of the present invention
(1) object under test is fixed on the sample stage, adopting wavelength is that 400nm～2500nm pulse laser incides on the testing sample, and the excitation testing sample produces photoacoustic signal;
(2) under the control of LabVIEW capture program, drive polynary ring detector array and testing sample stepping collection photoacoustic signal by the 3-D scanning platform, gather the photoacoustic signal data simultaneously;
(3) utilize MATLAB software to Signal Pretreatment of gathering and the image reconstruction that calculates phase-control focusing by computing machine, obtain the image of object under test then by backprojection algorithm.
The method of utilizing the device of embodiment 1 and embodiment 2 is to being embedded with the agar imaging of carbon-point.
Three carbon-point linearities vertically are embedded in agar, and depth of burial is respectively 4.5mm, 6mm and 7.2mm, and mutual spacing is respectively 1.8mm and 2.5mm, and wherein the diameter of carbon-point is 0.5mm.Drive polynary ring array detector of sound step-scan by the 3-D scanning platform and gather photoacoustic signal, scanning step is 0.1mm.Wherein the angle of sample rotation is 180 °, and the rotation step-length of stepper motor is 18 °.The gained image as shown in Figure 3.As seen from Figure 3, utilize the present invention to know accurate imaging to testing sample.
Claims (3)
1. dorsal mode light acoustic imaging method based on multiple phase control focusing ring array is characterized in that method step is:
(1) adopt pulse laser to incide on the testing sample, the excitation testing sample produces photoacoustic signal; The wavelength coverage of described pulse laser is 400nm～2500nm;
(2) testing sample or polynary ring detector array are driven by stepper motor and scan pattern reception photoacoustic signal dorsad, gather the photoacoustic signal data simultaneously, and wherein polynary ring detector array is a hollow structure, and the number of ring is no less than two;
(3) application data process software dynamic focusing a-scan that the photoacoustic signal of gathering is calculated phased realization degree of depth Z direction, the data of utilizing the two-dimensional scan of the point-to-point X-Y direction of stepper motor to gather again can the synthetic three-dimensional light absorption distributed image of back projection.
2. the dorsal mode light acoustic imaging method based on multiple phase control focusing ring array according to claim 1, it is characterized in that scanning described in the step (2) and collection are under software program control, drive polynary ring detector array or testing sample scans type collection photoacoustic signal dorsad by stepper motor, wherein the plane of a loop and the plane of scanning motion are same plane.
3. the dorsal mode light acoustic imaging method based on multiple phase control focusing ring array according to claim 1 is characterized in that it is to adopt the method for parallel or serial to gather photoacoustic signal that polynary ring detector array described in the step (2) receives photoacoustic signal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 200810030972 CN101251514B (en) | 2008-04-02 | 2008-04-02 | Dorsal mode light acoustic imaging method based on multiple phase control focusing ring array |
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| CN 200810030972 CN101251514B (en) | 2008-04-02 | 2008-04-02 | Dorsal mode light acoustic imaging method based on multiple phase control focusing ring array |
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| CN101251514B true CN101251514B (en) | 2011-07-27 |
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| CN102854141A (en) * | 2012-08-28 | 2013-01-02 | 曾吕明 | Portable integrated optical resolution type photoacoustic microscope |
| CN103211620B (en) * | 2013-04-26 | 2015-05-20 | 杨迪武 | Breast carcinoma early-stage detecting instrument based on annular array opto-acoustic sensing technology |
| CN108261209B (en) * | 2018-01-23 | 2021-07-23 | 湖南大学 | Improved high-resolution acoustic focusing photoacoustic endoscopic imaging back projection imaging method |
| CN112862924B (en) * | 2020-12-31 | 2022-11-25 | 哈尔滨工业大学（威海） | Image reconstruction method and device in multi-modal imaging and multi-modal imaging technical system |
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