CN112098336A - Laser ultrasonic scanning imaging device and laser ultrasonic scanning imaging system - Google Patents
Laser ultrasonic scanning imaging device and laser ultrasonic scanning imaging system Download PDFInfo
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- CN112098336A CN112098336A CN202010827326.7A CN202010827326A CN112098336A CN 112098336 A CN112098336 A CN 112098336A CN 202010827326 A CN202010827326 A CN 202010827326A CN 112098336 A CN112098336 A CN 112098336A
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- G—PHYSICS
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
Abstract
In order to solve the above technical problem, the present application provides a laser ultrasonic scanning imaging device and a laser ultrasonic scanning imaging system, and the laser ultrasonic scanning imaging device includes: a pulse laser for emitting a pulse laser; the bearing platform is used for placing a sample to be tested, and the sample to be tested generates ultrasonic waves under the excitation of the pulse laser; the detection device is used for carrying out ultrasonic detection on the sample to be detected; the bearing table is configured to be movable along a preset track so that the pulsed laser scans the sample to be detected. The application provides a laser ultrasonic scanning image device can detect the great sample that awaits measuring of volume or area.
Description
Technical Field
The invention relates to the technical field of laser ultrasonic nondestructive testing, in particular to a laser ultrasonic scanning imaging device and a laser ultrasonic scanning imaging system.
Background
The laser ultrasonic detection technology is a nondestructive detection technology for exciting and detecting ultrasonic waves by utilizing laser, and compared with the traditional piezoelectric ultrasonic technology, the laser ultrasonic detection technology has the advantages of non-contact, broadband, point transmission and reception and the like. Therefore, the method can be applied to material characterization, defect detection, machining process monitoring, and detection or monitoring of workpieces with complex shapes or equipment in special environments such as high temperature, high pressure, corrosion, radiation and the like.
The laser ultrasonic detection system comprises a laser ultrasonic excitation source and a detection system. The laser ultrasonic excitation source directly acts on the material to be detected through laser and excites ultrasonic waves taking a laser irradiation point as a source through a thermoelastic effect or an ablation effect. There are many ways for the detection system, and theoretically all methods capable of detecting vibration can be used for detecting ultrasonic waves, but the detection method is limited by frequency response, resolution, sensitivity, requirements on the detected surface and the use environment, and the like, and the detection method is a piezoelectric transducer (such as lead zirconate titanate piezoelectric ceramic PZT) detection method and an optical detection method. When the piezoelectric transducer detection method is used, a coupling agent is used, and the strict requirement is also imposed on the surface of a sample. The interferometric detection method is to measure the vibration displacement of a sample by directly using the surface of the sample as a mirror in a measurement arm of a michelson interferometer, irradiating the surface of the sample with a focused laser beam, causing interference between the reflected light from the surface and a reference beam split by a light source, causing a frequency shift of the beam, and detecting the frequency shift by a detector.
Disclosure of Invention
The embodiment of the invention provides a laser ultrasonic scanning imaging device and a laser ultrasonic scanning imaging system, which are used for detecting a sample to be detected with a large area or volume.
In order to solve the above technical problem, the present application provides a laser ultrasonic scanning imaging device, which includes: a pulse laser for emitting a pulse laser; the bearing platform is used for placing a sample to be tested, and the sample to be tested generates ultrasonic waves under the excitation of the pulse laser; the detection device is used for carrying out ultrasonic detection on a sample to be detected; the bearing table is configured to be movable along a preset track so that the pulsed laser scans a sample to be detected.
The bearing platform is configured to stay for a preset time at each sampling point when moving along the preset track so that the detection device can perform ultrasonic detection.
Wherein the plurality of sampling points are distributed in an array.
The laser ultrasonic scanning imaging device further comprises a deflection assembly, and the deflection assembly is arranged on a light path of the pulse laser and used for adjusting the deflection angle of the pulse laser.
The carrier table is configured to stay at each sampling point for a preset time when moving along the preset track, and the deflection assembly is configured to adjust the deflection angle of the pulse laser within the preset time so that the pulse laser scans a set area containing the sampling points.
The detection device is used for carrying out ultrasonic detection for multiple times in the scanning period of each set area to obtain multiple initial detection signals, and determining a final detection signal according to the average value of the multiple initial detection signals.
Wherein, detection device includes: the laser emitter is used for emitting detection laser; the laser receiver is used for receiving reflected laser formed by the detection laser reflected by the sample to be detected; and the processor is used for determining the displacement of the sample to be detected according to the detection laser and the reflected laser so as to carry out ultrasonic detection on the sample to be detected.
The laser ultrasonic scanning imaging device further comprises a dichroic mirror, the dichroic mirror is arranged on the light path of the pulse laser and the detection laser, and the dichroic mirror is used for transmitting one of the pulse laser and the detection laser and reflecting the other of the pulse laser and the detection laser, so that the laser formed by light transmission and the laser formed by reflection are parallel.
Wherein, laser ultrasonic scanning image device still includes: the driver is connected with the bearing platform and used for receiving the control instruction sent by the external equipment and controlling the movement of the bearing platform according to the control instruction; the pulse signal generator is connected with the bearing platform and the pulse laser and used for receiving the position feedback signal sent by the bearing platform and generating a pulse signal; the pulse laser is used for generating corresponding pulse laser according to the pulse signal.
Wherein the pulse signal generator is a function generator.
Wherein, laser ultrasonic scanning image device still includes: the synchronizer is connected with the pulse laser and the detection device and is used for generating a synchronization signal when the pulse laser generates pulse laser; the detection device is used for carrying out ultrasonic detection on the sample to be detected according to the synchronous signal and sending the detection signal to external equipment.
In order to solve the above technical problem, the present invention further provides a laser ultrasonic scanning imaging system, including: the laser ultrasonic scanning imaging device is any one of the laser ultrasonic scanning imaging devices provided by the application; and the control equipment is connected with the laser ultrasonic scanning imaging device and used for controlling the laser ultrasonic scanning imaging device to work and processing the detection signal acquired by the laser ultrasonic scanning imaging device so as to obtain a waveform image of the sample to be detected.
Through the scheme, the invention has the beneficial effects that: be different from prior art, the laser ultrasonic scanning image device that this application provided can follow along predetermineeing the orbit through the plummer configuration that will bear the weight of the sample that awaits measuring to make pulsed laser scan the sample that awaits measuring. By the mode, the defect that the pulse laser cannot detect a sample to be detected with a large volume or area due to the fact that the deflection angle of the pulse laser is limited in a traditional mode that the pulse laser deflects to scan the sample to be detected by changing the light path of the pulse laser is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts, wherein:
fig. 1 is a schematic structural diagram of a first embodiment of a laser ultrasonic scanning imaging apparatus provided in the present application;
FIG. 2 is a schematic distribution diagram of an embodiment of sampling points of a predetermined track of a carrier stage according to the present disclosure;
FIG. 3 is a schematic structural diagram of an embodiment of the detection device for detecting the surface of a sample to be detected according to the present application;
FIG. 4 is a schematic structural diagram of a second embodiment of a laser ultrasonic scanning imaging device provided in the present application;
FIG. 5 is a schematic structural diagram of a third embodiment of a laser ultrasonic scanning imaging apparatus provided in the present application;
FIG. 6 is a schematic diagram of a structure of a predetermined region including sampling points;
fig. 7 is a schematic structural diagram of a laser ultrasonic scanning imaging system provided in the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The laser ultrasonic detection imaging technology utilizes high-energy laser pulses to excite ultrasound and utilizes laser to detect the ultrasound, has the advantages of non-contact, remote detection and the like, and is particularly suitable for severe environment occasions, such as the use under the conditions of high temperature, corrosive radiation, higher movement speed of a sample to be detected and the like.
The inventor of the application finds that the existing scanning imaging device only deflects the laser by adjusting the laser light path, so as to scan the surface of the sample to be detected. Because the laser scans the sample to be detected by adjusting the light path under normal conditions, the deflection angle of the light beam is limited, and the laser is suitable for some samples to be detected with smaller volume or area. The laser ultrasonic scanning imaging device provided by the inventor of the application can comprehensively scan a sample to be detected with a large area or volume.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a first embodiment of a laser ultrasonic scanning imaging apparatus provided in the present application. Specifically, the laser ultrasonic scanning imaging apparatus 100 includes: a pulse laser 101, a carrying platform 104, a driver 105, a pulse signal generator 106, a synchronizer 102 and a detection device 103.
The pulse laser 101 is used for emitting pulse laser, and the pulse laser generated by the pulse laser 101 is used as a detection signal source, and when the detection signal source is projected to the surface of a sample to be detected, instantaneous and violent thermal expansion is generated, so that thermal excitation ultrasonic waves are generated. Moreover, the thermal excitation ultrasonic wave can propagate to the interior of the sample to be detected along the surface of the sample to be detected, and when the thermal excitation ultrasonic wave passes through the defects in the sample to be detected, the waveform of the thermal excitation ultrasonic wave can be abnormally changed. In fig. 1, the pulsed laser refers to an optical path represented by a thick arrow directed from the pulsed laser 101 to the stage 104.
The pulse laser 101 provided in this embodiment may be one of a Yttrium Aluminum Garnet (YAG) laser, a ruby laser, a neodymium glass laser, a nitrogen molecule laser, and an excimer laser.
The choice of the type of pulsed laser 101 depends on what form of ultrasound needs to be excited in the sample to be tested and the bandwidth of the ultrasound desired. The main parameters of the pulsed laser 101 are wavelength, energy, pulse duration and repetition rate. The selection of the laser wavelength depends on the absorption performance of the sample material to be detected, and the laser wavelength range can be selected from ultraviolet, infrared and even wider ranges. The energy of the laser depends on the sample material to be measured, and the laser energy can be used to excite the ultrasonic wave from nano-focus, micro-focus or even hundreds of joules according to whether the loss caused by the laser is acceptable. The repetition rate is very important to the detection speed.
The bearing table 104 is used for placing a sample to be tested, and the sample to be tested generates ultrasonic waves under the excitation of the pulse laser. The stage 104 is configured to move along a predetermined trajectory so that the pulsed laser scans the sample to be measured.
Specifically, the preset trajectory includes a plurality of sampling points, and the plummer 104 is configured to stay at each sampling point for a preset time while moving along the preset trajectory, so that the detection device 103 performs ultrasonic detection.
Optionally, referring to fig. 2, fig. 2 is a distribution schematic diagram of an embodiment of sampling points of a preset track of the carrier stage according to the present application. Specifically, the plurality of sampling points are distributed in an array, and the respective row pitches of the array may be the same or different, and likewise, the respective column pitches may be the same or different. The array comprises in total aijA number of sample points, where aijThe sample points in the ith row and the jth column are represented, i is 1,2, … …, N, j is 1,2, … …, M (N, M are positive integers), and the sample point array has a total of N × M sample points. The carrier 104 may be in accordance with { a }11,a12,……，a1M,a2M，a2(M-1)… …, it is clear that the distance that the carrier 104 moving according to this trajectory needs to move is the shortest. Of course, the carrier 104 can also move according to any other predetermined trajectory, such as { a }11,a12,……，a1M,a21，……，a2MIs it? … such that each row of sample points moves in an end-to-end motion. It is understood that the predetermined track of the movement of the carrier 104 is not limited in any way as long as the carrier 104 can stay at each sampling point for a predetermined time.
It can be understood that the more sampling points included in the preset track, the smaller the distance between the sampling points, and the higher the resolution of the image obtained by performing laser ultrasonic detection imaging on the sample to be detected. Therefore, the present embodiment can increase the resolution of the detected image by changing the distance between the sampling points.
When the stage 104 moves to a certain sampling point, the pulse laser 101 emits a pulse laser to a point of the sample to be measured, and for convenience, this point is referred to as an irradiation point in this embodiment. Obviously, each sampling point will have a corresponding illumination point. In order to enable the sample to be detected to be scanned by the pulse laser pulse when the sample to be detected moves to each sampling point, the distance between every two sampling points at least needs to be less than or equal to the minimum side length of the sample to be detected.
It can be understood that, according to the difference between the sampling point included in the preset track and the position of the sampling point, the laser ultrasonic scanning imaging apparatus 100 provided in the present application can detect different sub-regions of the sample to be detected. For example, in some ways, it is determined that a defect is located in a certain region of the sample to be tested, and at this time, a corresponding preset track may be designed according to the defect region for the movement of the carrier stage 104, so as to scan and image the region.
In order to ensure the detection efficiency, a pulsed laser with a high repetition rate is generally selected to scan the sample to be detected. The scanning time is shortened. However, in order to make the excited ultrasonic information distinguishable, the ultrasonic information excited by the previous single pulse and the ultrasonic information excited by the next single pulse laser cannot generate the phenomenon of ultrasonic field superposition, so the time interval of laser excitation cannot be too short.
Alternatively, since the laser emitted by the pulse laser 101 is relatively divergent and the path is difficult to control, it may be difficult to achieve the effect expected by the experiment by directly injecting the pulse laser to the surface of the sample to be measured, and thus the pulse laser may be focused by the present embodiment. Specifically, the focusing mirror is arranged on the light path of the pulse laser, so that the pulse laser can be accurately emitted to the surface of the sample to be detected.
The preset time for the plummer 104 to stay at each sampling point not only needs to ensure that the detection device 103 collects a set number of ultrasonic signals, but also needs to be greater than or equal to the repetition times of the pulse laser multiplied by the time interval of the pulse laser excitation. In other words, the pulsed laser 101 is in an unfired state during the movement of the stage 104 according to the preset trajectory.
Each time the carrier 104 moves to a sampling point, a position feedback signal is generated, and the position feedback signal reflects the current position of the carrier 104 or information of the sampling point to which the carrier 104 moves.
And the driver 105 is connected with the bearing platform 104 and is used for receiving the control command sent by the external device and controlling the movement of the bearing platform 104 according to the control command. The external device of the embodiment may be a computer, a mobile terminal, a tablet computer, or the like.
And the pulse signal generator 106 is connected with the bearing platform 104 and the pulse laser 101 and is used for receiving the position feedback signal sent by the bearing platform 104 and generating a pulse signal, and the pulse laser 101 is used for generating corresponding pulse laser according to the pulse signal.
In one embodiment, the pulse signal generator 106 may be a function generator. The function generator is a circuit or an instrument capable of automatically generating voltage waveforms of sine waves, square waves and triangular waves with certain frequency, amplitude and pulse width.
Specifically, each time the carrier 104 moves to a sampling point, a position feedback signal reflecting the current position information of the carrier 104 is generated and sent to the pulse signal generator 106. The pulse laser 101 generates corresponding pulse laser light according to the pulse signal.
The detection device 103 is used for performing ultrasonic detection on a sample to be detected. Referring to fig. 3, fig. 3 is a schematic structural diagram of an embodiment of the detection device of the present embodiment for detecting the surface of the sample to be detected. Specifically, the detection device 103 includes: a laser transmitter 1031, a laser receiver 1032, and a processor 1033. A laser transmitter 1031 for transmitting detection laser light; the laser receiver 1032 is used for receiving reflected laser formed by the detection laser reflected by the sample to be detected; the processor 1033 may be disposed inside the laser receiver 1032, for example, and is configured to determine a displacement of the sample to be tested according to the detection laser and the reflected laser, so as to perform ultrasonic testing on the sample to be tested.
According to the embodiment, any optical method can be selected according to actual conditions to carry out ultrasonic detection on the sample to be detected. For example, non-interference detection techniques include edge detection techniques, surface grating diffraction techniques, and reflectivity detection techniques, among others. The interference detection technology comprises a self-differencing and heterodyne interference detection technology, a confocal Fabry-Perot interference detection technology, a phase conjugate interference detection technology, a double-wave mixed interference detection technology, a light induced electromotive force interference detection technology and the like.
Taking the self-differential interference detection technology as an example, detection pulse laser emitted by the laser emitter 1031 is first divided into two paths by the beam splitter, one path of detection laser beam is focused by the lens and then enters the surface of the sample to be detected, reflected laser reflected by the surface of the sample to be detected enters the laser receiver 1032 after passing through the beam splitter, the other path of detection laser beam also enters the laser receiver 1032 after passing through the reflector and the beam splitter, the two paths of detection laser beam interfere with each other, the frequency shift and the interference light intensity are detected by the processor 1033, and therefore displacement information of the ultrasonic vibration of the sample to be detected is obtained, and the displacement information is finally collected by external equipment such.
In addition, when scanning the irradiation point corresponding to each sampling point, the spot of the detection laser (the position at which the detection laser irradiates the surface of the sample to be measured) is located in the vicinity of the irradiation point, and generally, it is preferable that the distance between the detection laser spot and the pulse laser spot is not longer than the distance between the sampling point and each of the surrounding sampling points, and the distance between the detection laser spot and the pulse laser spot is always constant. In other words, the optical paths of the pulse laser light and the detection laser light are always kept unchanged.
The spot of the detection laser is generally selected to be the position where the detection sensitivity of the detection device 103 is highest, and the detection sensitivity is not higher as the spot of the detection laser is closer to the spot of the pulse laser. The distance between the pulse laser and the scanning laser can be adjusted by adjusting the light paths of the pulse laser and the scanning laser, and the distance is kept constant after the adjustment is completed.
In an embodiment, the laser ultrasonic scanning imaging apparatus 100 provided in this embodiment may further include an optical path adjusting device, where the optical path adjusting device is disposed on the optical path of the pulse laser, and the optical path adjusting device is adjusted by an external device such as a computer, so that the optical path of the pulse laser passing through the optical path adjusting device is deflected to a certain degree, and the pulse laser and the surface of the sample to be measured are irradiated to the surface of the sample to be measured at a certain angle. In this process, the distance between the pulse laser spot and the detection laser spot can be adjusted by adjusting the optical path of the pulse laser, so that the detection efficiency of the detection device 103 is higher.
In another embodiment, as shown in fig. 4, fig. 4 is a schematic structural diagram of a second embodiment of the laser ultrasonic scanning imaging apparatus provided in the present application. Specifically, the laser ultrasonic scanning imaging apparatus 100 further includes a dichroic mirror 107, the dichroic mirror 107 is disposed on the optical path of the pulse laser light and the detection laser light, and the dichroic mirror 107 is configured to transmit one of the pulse laser light and the detection laser light and reflect the other of the pulse laser light and the detection laser light, so that the laser light formed by transmission and the laser light formed by reflection are parallel.
A Dichroic mirror 107(Dichroic Mirrors), also known as Dichroic Mirrors, is commonly used in laser technology. The dichroic mirror/spectroscope transmits or reflects light according to wavelength to realize spectral splitting. The long-pass dichroic mirror highly reflects light below the cutoff wavelength and highly transmits light above the cutoff wavelength; short-pass dichroic mirrors, in contrast, highly transmit light below the cut-off wavelength and highly reflect light above the cut-off wavelength. Since the wavelength of the detection laser is generally shorter than that of the pulse laser, the dichroic mirror 107 may be used to transmit the pulse laser, reflect the detection laser, and make the pulse laser and the detection laser parallel to each other and vertically incident on the surface of the sample to be measured.
The detection device 103 performs ultrasonic detection on a sample to be detected by an optical method. The method is a novel nondestructive testing means, has the characteristics of non-contact, high sensitivity and the like, can overcome the defect that the conventional ultrasonic testing needs a coupling agent, and is a non-contact and broadband testing technology in the true sense.
A synchronizer 102, connected to the pulse laser 101 and the detection device 103, and particularly connected to a laser emitter 1031 in the detection device 103, for generating a synchronization signal when the pulse laser 101 generates pulse laser light; the detection device 103 is configured to perform ultrasonic detection on the sample to be detected according to the synchronization signal, and send a detection signal to an external device.
Specifically, the synchronizer 102 is also called a synchronization signal generator, and the synchronization signal is a signal for providing the same time reference for the machine devices which need to process information synchronously. The detection device 103 of the present embodiment knows the time point of the pulse laser 101 generating the pulse laser through the received synchronization signal, so as to emit the detection laser to perform ultrasonic detection on the sample to be detected while the pulse laser 101 emits the pulse laser.
When the pulse laser 101 generates pulse laser, a synchronization signal is generated, and the detection device 103 performs ultrasonic detection on the sample to be detected according to the synchronization signal and transmits the detection signal to an external device.
In summary, the working process of the laser ultrasonic scanning imaging apparatus 100 provided in this embodiment is that the bearing table 104 is driven by the driver 105, and after moving to a sampling point according to a preset track, generates and sends a position feedback signal corresponding to the sampling point to the pulse signal generator 106; the pulse signal generator 106 receives the position feedback signal and generates a pulse signal according to the position feedback signal, and the pulse laser 101 generates a corresponding pulse laser according to the pulse signal to scan the sample to be measured.
The pulse laser 101 generates pulse laser, and the synchronizer 102 generates a synchronization signal and sends the synchronization signal to the detection device 103, so that the detection device 103 emits detection laser to perform laser ultrasonic detection imaging on a sample to be detected while the pulse laser emits.
The laser ultrasonic scanning imaging device 100 provided by this embodiment receives the reflected laser formed by the detection laser reflected by the sample to be detected by the optical method, and this receiving manner can perform scanning detection on the sample to be detected with an uneven surface because it does not need a coupling medium and does not need to contact the sample to be detected.
Referring to fig. 5, fig. 5 is a schematic structural diagram of a third embodiment of the laser ultrasonic scanning imaging apparatus provided in the present application.
Specifically, the laser ultrasonic scanning imaging apparatus 100 provided by the present embodiment includes: a pulse laser 101, a carrier 104, a deflection assembly 108, a driver 105, a pulse signal generator 106, a synchronizer 102 and a detection device 103. It should be noted that the working states and functions of the pulse laser 101, the carrying platform 104, the driver 105, the pulse signal generator 106, the synchronizer 102 and the detection device 103 of the present embodiment are similar to those of the corresponding devices of the first embodiment, and reference may be specifically made to the description of the first embodiment, and the detailed description of the present embodiment is not repeated.
And the deflection component 108 is arranged on the light path of the pulse laser and used for adjusting the deflection angle of the pulse laser.
The deflection component 108 may be, for example, a scanning galvanometer, which is based on the principle that a laser beam is incident on two mirrors (scanning mirrors), the emission angles of the mirrors are controlled by using an external device such as a computer, and the two mirrors can scan along the X and Y axes, respectively, so that the laser scans different positions of the sample to be measured.
In the process of scanning the laser of the sample to be detected, the deflection component 108 is controlled by external equipment such as a computer, and particularly the deflection component 108 is controlled to rotate, so that the pulse laser deviates by a certain angle, and finally the pulse laser after deviation scans the sample to be detected.
The preset track includes a plurality of sampling points, the carrier 104 is configured to stay at each sampling point for a preset time when moving along the preset track, and the deflection assembly 108 is configured to adjust a deflection angle of the pulsed laser within the preset time, so that the pulsed laser scans a set area including the sampling points. Referring to fig. 6, fig. 6 is a schematic structural diagram of a preset region including sample points, a large rectangle on the left side of fig. 6 represents all the preset regions including sample points, and an enlarged view of the preset region including a sample point is shown on the right side of fig. 6. It is to be understood that the setting region including the sampling points is not limited to a rectangular region, but may be a region of various forms, such as a circular region, or various regions of irregular shapes, and is not particularly limited herein.
The detection device 103 is configured to perform ultrasonic detection a plurality of times during a scanning period for each set region to obtain a plurality of initial detection signals, and determine a final detection signal from an average value of the plurality of initial detection signals.
Optionally, in consideration of improving the accuracy and integrity of the detection scan, the set areas of each sampling point do not overlap with each other, and the union of the set areas of all sampling points constitutes the whole surface area of the sample to be detected.
In addition, when the set area of each sampling point is scanned, the spot of the detection laser (the position of the detection laser irradiating the surface of the sample to be measured) is located at a certain position, such as the center position or the position of the sampling point, within the set area, and the spot of the pulse laser (the position of the pulse laser irradiating the surface of the sample to be measured) is variable within the set area according to the deflection of the deflection assembly 108 to the pulse laser, that is, the distance between the spot of the pulse laser and the spot of the detection laser is not fixed, but changes with the change of the position of the spot of the pulse laser.
Specifically, under the action of the deflection assembly 108, the pulsed laser scans a set area including the currently used point according to a pre-planned scanning path. The detection device 103 emits a pulse detection laser with a certain repetition rate to collect a plurality of detection signals, and finally takes an average signal of the collected plurality of detection signals to input to an external device, and takes the average signal as a final detection signal of a current sampling point.
When scanning each set area including the sampling point, the scanning path of the pulsed laser may include a plurality of scanning points, and the pulsed laser is deflected by the deflection assembly 108 when scanning each scanning point.
The laser ultrasonic scanning imaging device 100 provided in this embodiment can utilize the bearing platform 104 to drive the sample to be detected to move according to the preset track, so as to scan the sample to be detected in a large range; on the other hand, in a set area including each sampling point, the deflection component 108 is utilized to deflect the pulse laser so as to detect a plurality of scanning points in the set area, and finally, the average value of a plurality of collected ultrasonic signals is used as a detection value corresponding to the sampling point, so that the scanning speed of the laser ultrasonic scanning imaging device 100 can be improved.
Referring to fig. 7, fig. 7 is a schematic structural diagram of a laser ultrasonic scanning imaging system provided in the present application. The laser ultrasonic scanning imaging system 1000 includes: any one of the laser ultrasonic scanning imaging devices 100 provided above; and the control device 200 is connected to the laser ultrasonic scanning imaging device 100, and is configured to control the laser ultrasonic scanning imaging device 100 to operate, and process the detection signal acquired by the laser ultrasonic scanning imaging device 100 to obtain a waveform image of the sample to be detected.
Alternatively, the control device 200 may be a mobile device such as a computer, tablet computer, or the like.
The laser ultrasonic scanning imaging system 1000 provided by the present application may further include a data acquisition card, and the laser ultrasonic scanning imaging apparatus 100 is connected to the control device 200 through the data acquisition card. Specifically, after the detection device 103 detects a sample to be detected and acquires a detection signal, a data acquisition card is used to perform digital-to-analog conversion, and transmit data to the control device 200, so as to realize imaging and analysis of the detection signal, and feed back a detection result.
In summary, the laser ultrasonic scanning imaging apparatus 100 provided in the present application can not only detect the thermally excited ultrasonic signal generated by the sample to be detected by the optical method, so as to realize the non-contact detection of the sample to be detected, but also can move according to the preset track by configuring the plummer 104, so as to further realize the detection of the sample to be detected with a large area or volume.
The above embodiments are only specific embodiments in the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can understand that the modifications or substitutions within the technical scope disclosed in the present application are all covered by the scope of the present application, and therefore, the scope of the present application should be subject to the protection scope of the claims.
Claims (12)
1. A laser ultrasonic scanning imaging device is characterized by comprising:
a pulse laser for emitting a pulse laser;
the bearing platform is used for placing a sample to be tested, and the sample to be tested generates ultrasonic waves under the excitation of the pulse laser;
the detection device is used for carrying out ultrasonic detection on the sample to be detected;
the bearing table is configured to be movable along a preset track so that the pulsed laser scans the sample to be detected.
2. The laser ultrasonic scanning imaging device of claim 1,
the preset track comprises a plurality of sampling points, and the plummer is configured to stay for a preset time at each sampling point when moving along the preset track so that the detection device performs ultrasonic detection.
3. The laser ultrasonic scanning imaging device of claim 2,
the plurality of sampling points are distributed in an array.
4. The laser ultrasonic scanning imaging device of claim 1,
the laser ultrasonic scanning imaging device further comprises a deflection assembly, wherein the deflection assembly is arranged on a light path of the pulse laser and is used for adjusting the deflection angle of the pulse laser.
5. The laser ultrasonic scanning imaging device of claim 4,
the preset track comprises a plurality of sampling points, the bearing platform is configured to stay at each sampling point for a preset time when moving along the preset track, and the deflection assembly is configured to adjust the deflection angle of the pulse laser within the preset time so that the pulse laser scans a set area containing the sampling points.
6. The laser ultrasonic scanning imaging device of claim 5,
the detection device is used for carrying out ultrasonic detection for multiple times during the scanning period of each set area to obtain multiple initial detection signals, and determining a final detection signal according to the average value of the multiple initial detection signals.
7. The laser ultrasonic scanning imaging device of claim 1,
the detection device includes:
the laser emitter is used for emitting detection laser;
the laser receiver is used for receiving reflected laser formed by reflecting the detection laser by the sample to be detected;
and the processor is used for determining the displacement of the sample to be detected according to the detection laser and the reflected laser so as to carry out ultrasonic detection on the sample to be detected.
8. The laser ultrasonic scanning imaging device of claim 7,
the laser ultrasonic scanning imaging device further comprises a dichroic mirror, the dichroic mirror is arranged on the light path of the pulse laser and the detection laser, and the dichroic mirror is used for transmitting one of the pulse laser and the detection laser and reflecting the other of the pulse laser and the detection laser, so that the laser formed by light transmission and the laser formed by reflection are parallel.
9. The laser ultrasonic scanning imaging device of claim 1,
the laser ultrasonic scanning imaging device further comprises:
the driver is connected with the bearing platform and used for receiving a control command sent by external equipment and controlling the movement of the bearing platform according to the control command;
the pulse signal generator is connected with the bearing platform and the pulse laser and used for receiving the position feedback signal sent by the bearing platform and generating a pulse signal;
the pulse laser is used for generating corresponding pulse laser according to the pulse signal.
10. The laser ultrasonic scanning imaging device of claim 9,
the pulse signal generator is a function generator.
11. The laser ultrasonic scanning imaging device of claim 9,
the laser ultrasonic scanning imaging device further comprises:
the synchronizer is connected with the pulse laser and the detection device and is used for generating a synchronization signal when the pulse laser generates pulse laser;
the detection device is used for carrying out ultrasonic detection on the sample to be detected according to the synchronous signal and sending a detection signal to the external equipment.
12. A laser ultrasonic scanning imaging system, comprising:
a laser ultrasonic scanning imaging device, wherein the laser ultrasonic scanning imaging device is the laser ultrasonic scanning imaging device as claimed in any one of claims 1 to 11;
and the control equipment is connected with the laser ultrasonic scanning imaging device and used for controlling the laser ultrasonic scanning imaging device to work and processing the detection signal acquired by the laser ultrasonic scanning imaging device so as to obtain a waveform image of the sample to be detected.
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