CN109612940B - Nondestructive testing system and nondestructive testing method for rapidly controlling generation of ultrasound by laser array - Google Patents
Nondestructive testing system and nondestructive testing method for rapidly controlling generation of ultrasound by laser array Download PDFInfo
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Abstract
The invention discloses a nondestructive testing system and a nondestructive testing method for generating ultrasonic fast control by a laser array, wherein the system comprises a laser generator, a laser transmission device, an ultrasonic testing device, a multi-channel analog-to-digital conversion device and a controller, laser emitted by the laser generator is irradiated to the surface of a sample to be tested through the laser transmission device, ultrasonic waves are generated under a thermoelastic mechanism, the ultrasonic waves propagated in the sample to be tested are detected by the ultrasonic testing device, information of the sample to be tested is transmitted to the controller through the multi-channel analog-to-digital conversion device, initial characteristic information to be tested is analyzed, and the laser transmission device is fed back and adjusted, so that the accurate measurement of the characteristic to be tested in the sample to be tested is realized. According to the detected characteristic information, the intensity of the ultrasonic wave at the fixed point and/or the orientation is quickly adjusted, the signal-to-noise ratio and the detection capability of the laser ultrasonic nondestructive detection system are greatly improved, and the efficiency of accurately detecting the detected characteristic is improved.
Description
Technical Field
The invention belongs to the field of nondestructive testing, and particularly relates to a nondestructive testing system and a nondestructive testing method for rapidly controlling ultrasonic generation by a laser array pair.
Background
In the present nondestructive testing field, ultrasonic testing is one of the most important methods, and is widely applied to safety testing of various important equipment structures. The excitation mode of ultrasonic wave in the structure can be divided into a piezoelectric ultrasonic method, an electromagnetic ultrasonic method and a laser ultrasonic method. The piezoelectric ultrasonic wave needs to contact a probe with a tested piece and needs to use a liquid coupling agent, and the electromagnetic ultrasonic wave does not need to contact the tested piece but has a small spacing distance; laser ultrasound uses laser excitation and detection ultrasound, has the advantages of long distance, non-contact, high resolution and the like, and is receiving more and more attention in the industrial fields of nondestructive detection and the like.
However, in the thermoelastic mechanism, ultrasonic bulk waves (longitudinal waves and transverse waves) excited by single-point laser in the structure are weak, the signal-to-noise ratio of the system is low, and the detection of the detected features inside the structure is not facilitated, so that it is necessary to enhance the intensity of the ultrasonic waves by methods such as phased array laser excitation to realize the detection of the detected features inside the structure. However, most of the existing array laser methods are to directionally enhance the ultrasonic waves through a single optical fiber array, the beam control capability of the system to the ultrasonic waves is too single, the ultrasonic waves cannot be rapidly adjusted according to the detected characteristics of the sample, and the detection precision is limited to a certain extent in the actual detection process.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the problems in the existing application and technology, a nondestructive testing system and a nondestructive testing method for rapidly controlling the generation of ultrasonic waves by a laser array pair are provided, the strength of ultrasonic waves at fixed points and orientation is rapidly adjusted according to detected characteristic information, the signal-to-noise ratio and the detection capability of the laser ultrasonic nondestructive testing system are greatly improved, and the efficiency of accurately detecting the detected characteristics is improved.
The technical scheme is as follows: in order to achieve the purpose of the invention, the invention adopts the following technical scheme:
the utility model provides a laser array is to generating nondestructive test system of supersound quick control, including laser generator, laser transmission device, ultrasonic detection device, multichannel analog-to-digital conversion equipment and controller, the laser that laser generator sent shines the sample surface that awaits measuring through laser transmission device, produce the ultrasonic wave under the thermoelastic mechanism, the ultrasonic wave of spreading in the sample that awaits measuring is detected by ultrasonic detection device, and transmit the information of the sample that awaits measuring to the controller through multichannel analog-to-digital conversion equipment, analyze the initial characteristic information of examining, and feedback adjustment conversion laser transmission device, realize the accurate measurement of the characteristic of examining in the sample that awaits measuring.
Optionally, the laser transmission device includes a convex lens, a conversion device of an optical fiber coupler, an optical fiber coupler array, an optical fiber array, and a focusing lens array, where the optical fiber coupler array is installed on the conversion device of the optical fiber coupler and includes at least two optical fiber couplers; the optical fiber array is at least two, and the focusing lens array comprises at least two focusing lenses; the optical fiber couplers, the optical fiber array and the focusing lens correspond to each other one by one, and laser emitted by the laser generator is focused on the optical fiber couplers through the convex lens, transmitted through the optical fiber array and then irradiated on the surface of a sample to be measured through the focusing lens.
Optionally, the conversion device of the optical fiber coupler is a ± 180 ° coaxial rotation converter device, the angle of each rotation is determined according to the specific number of the installed optical fiber couplers, if there are n optical fiber couplers, the angle of each rotation is an integer multiple of 2 pi, and the conversion device of the optical fiber coupler is connected to the controller for automatic conversion or manual conversion.
n
Optionally, the number and distance of the optical fibers of the optical fiber array connected to each optical fiber coupler and the matching of the lengths of the optical fibers are the same or different.
Optionally, the nondestructive testing system further includes an electric control displacement table and a first stepping motor, the sample to be tested is placed on the electric control displacement table, the first stepping motor is connected with the controller, the controller controls the first stepping motor to rotate, and the movement of the sample to be tested is further controlled by controlling the electric control displacement table.
Optionally, the nondestructive testing system further includes a second stepping motor, the second stepping motor is connected to the conversion device of the optical fiber coupler, the ultrasonic wave propagated in the sample to be tested is detected by the ultrasonic testing device, and the information of the sample to be tested is transmitted to the controller through the multi-channel analog-to-digital conversion device, so as to obtain the initial characteristic information to be tested; the controller controls the second stepping motor to adjust the conversion device of the conversion optical fiber coupler, and selects the corresponding optical fiber coupler of the optical fiber array, so that the strength of the generated ultrasonic wave at a fixed point or orientation is improved, and the accurate measurement of the detected characteristics in the sample to be detected is realized.
In another embodiment of the present invention, a nondestructive testing method for rapidly controlling generation of ultrasound by a laser array pair is further provided, which comprises the following steps:
(1) firstly, laser excites ultrasonic waves in a sample to be detected through an initially arranged optical fiber coupler, and ultrasonic signals detected by an ultrasonic detection device are transmitted to a controller through a multi-channel analog-to-digital conversion device;
(2) the controller processes the ultrasonic signals and displays waveforms, analyzes whether the ultrasonic signals contain the detected characteristic information of the sample to be detected, and moves the sample to be detected to continue scanning if the ultrasonic signals do not contain the detected characteristic information of the sample to be detected; if so, determining a proper optical fiber array according to the detected initial characteristic information of the sample to be detected;
(3) adjusting by using an optical fiber coupler conversion device, selecting a proper optical fiber coupler and an optical fiber array, and focusing excitation laser to the corresponding optical fiber array to form a laser array pair; carrying out fixed-point or directional ultrasonic enhancement on the detected initial characteristic information of the sample to be detected;
(4) the enhanced detected characteristic information detected by the ultrasonic detection device is transmitted to a controller for analysis and processing through a multi-channel analog-to-digital conversion device;
(5) the controller analyzes whether the sample to be detected is scanned completely, and if the sample to be detected is scanned completely, the system finishes and stops working; and if not, performing plane scanning on the sample to be detected by moving the sample to be detected, and repeating the steps (1) to (5) to realize accurate measurement of the position, the shape and the size of the detected feature in the sample to be detected.
Further, the method for determining the appropriate optical fiber array according to the detected initial characteristic information of the sample to be detected in the step (2) comprises the following steps:
the method comprises the steps of analyzing the detected initial characteristic information of a sample to be detected by utilizing the prior art, matching the position, the shape and the size of the detected characteristic with the position of a fixed-point reinforcing point or the directional reinforcing direction of an optical fiber array, and finding out the best matching optical fiber array of the system, wherein the matching rule is to select the closest optical fiber array.
Further, the specific method for performing fixed-point ultrasonic enhancement on the detected initial characteristic information of the sample to be detected in the step (3) is as follows: firstly, determining the distance and angle of a position point needing to enhance the ultrasonic intensity relative to an ultrasonic source irradiated by laser on the surface of a sample to be detected, and then calculating the length of an optical fiber required by an optical fiber array to enable the ultrasonic wave fronts generated by the irradiation of the optical fibers of the optical fiber array on the sample to arrive at the position point at the same time, so as to realize the coherent enhancement of the ultrasonic wave at the determined position point; the calculation formula is as follows:
if the optical fiber array has m optical fibers, the lengths thereof are Li(i is more than or equal to 1 and less than or equal to m), and the distances between the corresponding laser irradiation points, namely the ultrasonic wave generation points and the position points needing to enhance the ultrasonic wave intensity are respectively Di(1. ltoreq. i. ltoreq.m), then:
wherein i is more than or equal to 1 and less than or equal to m-1, c is the propagation speed of the laser in the optical fiber, and v is the propagation speed of the used ultrasonic wave mode in the sample to be detected.
Further, the specific method for performing directional ultrasonic enhancement on the detected initial characteristic information of the sample to be detected in the step (3) is as follows: firstly, determining the angle of the direction of ultrasonic intensity to be enhanced relative to an ultrasonic source irradiated on the surface of a sample to be detected by laser, and then calculating the length of optical fibers required by an optical fiber array to enable the ultrasonic wave front generated by the irradiation of the optical fibers of the optical fiber array on the sample to be detected to arrive at the same time on a vertical plane of the direction, thereby realizing the coherent enhancement of the ultrasonic wave in the determined direction; the calculation formula is as follows:
if the optical fiber array has m optical fibers, the lengths thereof are Li(i is more than or equal to 1 and less than or equal to m), and the distances between the corresponding laser irradiation point, namely the ultrasonic wave generation point, and a certain vertical plane in the direction needing to enhance the ultrasonic wave intensity are Si(1. ltoreq. i. ltoreq.m), then:
wherein i is more than or equal to 1 and less than or equal to m-1, c is the propagation speed of the laser in the optical fiber, and v is the propagation speed of the used ultrasonic wave mode in the sample to be detected.
Has the advantages that: compared with the prior art, the invention has the following advantages:
when the invention is used for detecting a sample, the approximate information of the detected characteristics fed back by the detection device can be quickly adjusted by utilizing the converter device of the optical fiber coupler to focus laser on the optical fiber array matched with the required length, the fixed point or the directional strength of the generated ultrasonic wave is improved, the accurate measurement of the position, the shape and the size of the detected characteristics in the sample is realized, the planar scanning of the sample can be realized by moving the sample, the signal-to-noise ratio and the detection capability of a laser ultrasonic nondestructive detection system are greatly improved, and the efficiency of the accurate detection of the detected characteristics is improved.
Drawings
FIG. 1 is a schematic block diagram of one embodiment of the system of the present invention;
FIG. 2 is a schematic diagram of a fixed point enhanced laser generating ultrasound;
FIG. 3 is a schematic illustration of directionally enhanced laser generated ultrasound;
FIG. 4 is a flow chart of the steps of the detection method of the present invention.
Detailed Description
For a further understanding of the invention, one embodiment of the invention is described below, but it is to be understood that the description is intended to illustrate further features and advantages of the invention, and not to limit the claims. The following description of the embodiments is only intended to aid in the understanding of the method of the invention and its core ideas. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
The utility model provides a laser array is to generating nondestructive test system of supersound quick control, including laser generator, laser transmission device, ultrasonic detection device, multichannel analog-to-digital conversion equipment and controller, the laser that laser generator sent shines the sample surface that awaits measuring through laser transmission device, produce the ultrasonic wave under the thermoelastic mechanism, the ultrasonic wave of spreading in the sample that awaits measuring is detected by ultrasonic detection device, and transmit the information of the sample that awaits measuring to the controller through multichannel analog-to-digital conversion equipment, analyze the initial characteristic information of examining, and feedback adjustment conversion laser transmission device, realize the accurate measurement of the characteristic of examining in the sample that awaits measuring.
The laser transmission device comprises a convex lens, a conversion device of an optical fiber coupler, an optical fiber coupler array, an optical fiber array and a focusing lens array, wherein the optical fiber coupler array is arranged on the conversion device of the optical fiber coupler and comprises at least two optical fiber couplers; the optical fiber array is at least two, and the focusing lens array comprises at least two focusing lenses; the optical fiber couplers, the optical fiber array and the focusing lens correspond to each other one by one, and laser emitted by the laser generator is focused on the optical fiber couplers through the convex lens, transmitted through the optical fiber array and then irradiated on the surface of a sample to be measured through the focusing lens.
The ultrasonic detection device can be an interferometer or a piezoelectric ceramic probe, and ultrasonic signals detected by the ultrasonic detection device are input into the multi-channel analog-to-digital conversion equipment, and the multi-channel analog-to-digital conversion equipment is connected with a computer to display waveforms in various modes. Analyzing whether the detected characteristic information of the sample to be detected is contained or not according to the displayed waveform, and if not, moving the sample to be detected to continue scanning; if the detected characteristic exists, according to the approximate position and direction of the detected characteristic (detected initial characteristic information), a proper optical fiber array can be quickly selected by using a conversion device of the optical fiber coupler, fixed-point and directional ultrasonic enhancement is carried out on the known detected initial characteristic information, the signal-to-noise ratio of an ultrasonic signal obtained by a detection device is further improved, and the detection accuracy of the detected characteristic of the sample to be detected is improved.
The conversion device of the optical fiber coupler is a converter device which rotates coaxially within +/-180 degrees, the angle of each rotation is determined according to the specific number of the installed optical fiber couplers, and if n optical fiber couplers are arranged, the angle of each rotation is
And the conversion device of the optical fiber coupler is automatically converted or manually converted by a connection controller.
The number and distance of the optical fibers of the optical fiber array connected with each optical fiber coupler and the length collocation of the optical fibers can be the same or different, and the specific numerical value needs to be set according to the shape and size of the actual sample to be detected and the measurement precision required by detection. The length collocation of the optical fibers of the optical fiber array connected with each optical fiber coupler can be preset according to two methods to realize the improvement of the fixed point or the directional strength of the generated ultrasonic waves, and the method specifically comprises the following steps:
the first method is that the distance and angle of the position point needing to strengthen the ultrasonic wave intensity relative to the ultrasonic source irradiated by the laser on the surface of the sample to be measured are determined, and then the length of the optical fiber required by the array is calculated to enable the ultrasonic wave front generated by irradiating the optical fibers of the array on the sample to be measured to arrive at the position point at the same time, so as to realize the coherent strengthening of the ultrasonic wave on the determined position point.
The second method is that the angle of the direction of the ultrasonic intensity to be enhanced relative to the ultrasonic source irradiated on the surface of the sample to be measured by the laser is determined, and then the length of the optical fiber required by the array is calculated to enable the ultrasonic wave front generated by the irradiation of the optical fibers of the array on the sample to be measured to arrive at the same time on the vertical plane of the direction, so that the coherent enhancement of the ultrasonic wave in the determined direction is realized.
The nondestructive testing system also comprises an electric control displacement platform and a first stepping motor, the sample to be tested is placed on the electric control displacement platform, the first stepping motor is connected with the controller, the controller controls the first stepping motor to rotate, and the movement of the sample to be tested is further controlled by controlling the electric control displacement platform.
The nondestructive testing system also comprises a second stepping motor, the second stepping motor is connected with the conversion device of the optical fiber coupler, the controller controls the second stepping motor to adjust the conversion device of the conversion optical fiber coupler, and the optical fiber coupler of the corresponding optical fiber array is selected, so that the fixed-point or directional strength of the generated ultrasonic wave is improved, and the accurate measurement of the detected characteristics in the sample to be tested is realized.
Example (b):
as shown in fig. 1, in an embodiment of the present invention, a nondestructive testing system for rapidly controlling generation of ultrasound by a laser array pair is provided, which includes a pulse laser 1, a convex lens 2, a fiber coupler converter device 3, a fiber coupler 4, a fiber array 5, a focusing lens 6, a sample 7 to be tested, an electrically controlled displacement stage 8, an ultrasonic testing device 9, a multi-channel analog-to-digital conversion device 10, a computer 11, a first stepping motor 12 and a second stepping motor 13.
When the nondestructive testing system in this embodiment works, a pulse laser beam is emitted from a pulse laser 1, the pulse laser beam is focused to an optical fiber coupler 4 on a converter device 3 of the optical fiber coupler through a convex lens 2, and is propagated through an initially set optical fiber array 5 with matched length, so that the pulse laser beam irradiates the surface of a sample 7 to be tested through a focusing lens 6 from each optical fiber, ultrasonic waves are generated under a thermo-elastic mechanism, the ultrasonic waves propagated in the sample 7 to be tested are detected by an ultrasonic detection device 9, information of the sample 7 to be tested is transmitted to a computer 11 through a multi-channel analog-to-digital conversion device 10, analysis of the approximate position and direction of the tested feature is realized, the computer 11 further controls a second stepping motor 13 to convert the converter device 3 of the optical fiber coupler, the optical fiber coupler 4 corresponding to the optical fiber array 5 is selected, so that the emitting time of the pulse laser beam from each optical fiber of the optical fiber array is different, that is, the time of irradiating on the surface of the sample 7 to be detected is different, so that the intensity of the generated ultrasonic wave at the fixed point or the orientation is improved, the ultrasonic wave transmitted in the sample 7 to be detected is detected by the ultrasonic detection device 9 again, and the information of the sample 7 to be detected is transmitted to the computer 11 through the multi-channel analog-to-digital conversion device 10, thereby realizing the accurate measurement of the position, the shape and the size of the detected characteristic in the sample. In addition, the sample 7 to be detected is placed on the electric control translation stage 8, and the first stepping motor 12 under the electric control translation stage is connected with the computer 11 so as to automatically control the movement of the sample to be detected according to the detection requirement (in addition, the sample to be detected can also be manually moved), thereby realizing plane scanning, greatly improving the signal-to-noise ratio and the detection capability of the laser ultrasonic nondestructive detection system, and improving the speed and the efficiency of the accurate detection of the detected characteristics.
As shown in fig. 2, in order to obtain the signal intensity improvement of the ultrasonic wave at the fixed point 16, the ultrasonic wave fronts 15 generated by the three ultrasonic sources must reach the fixed point 16 at the same time, so it is necessary to calculate the distance from each ultrasonic source to the fixed point divided by the propagation speed of the bulk wave in the sample 7 to be measured, and then compensate the time by using different fiber lengths of the fiber array 5 (after passing through the focusing lens), so that the length of each fiber of the fiber array 5 divided by the propagation speed of the light in the fiber and the total time for the ultrasonic wave fronts generated by the outgoing laser 14 irradiating the sample through the focusing lens to propagate to the fixed point 16 are the same, that is, the ultrasonic wave fronts reach the fixed point 16 at the same time, thereby realizing the coherent enhancement of the ultrasonic wave at the fixed point 16.
As shown in fig. 3, where 18 is a normal line of a surface of a sample 7 to be measured, in order to improve the signal intensity of an ultrasonic wave at an orientation θ, it is necessary to make the ultrasonic wave fronts 15 generated by three ultrasonic sources reach a vertical plane 17 at the orientation θ at the same time, so it is necessary to calculate the distance from each ultrasonic source to the vertical plane 17 at the orientation θ divided by the propagation speed of a bulk wave in the sample 7 to be measured, and then use different lengths of the optical fiber array 5 to compensate for time, so that the length of each optical fiber of the optical fiber array 5 is divided by the propagation speed of light in the optical fiber and the total time for the ultrasonic wave fronts generated by irradiating the sample with the outgoing laser 14 after passing through the focusing lens to propagate to the vertical plane 17 at the orientation θ is the same, that is, that the ultrasonic wave fronts reach the vertical plane 17 at the orientation θ at the same time, thereby realizing coherent enhancement of the ultrasonic wave at the orientation θ.
As shown in fig. 4, a nondestructive testing method for generating ultrasonic fast control by laser array pair includes the following steps:
(1) firstly, laser excites ultrasonic waves in a sample to be detected through an initially arranged optical fiber coupler, and ultrasonic signals detected by an ultrasonic detection device are transmitted to a controller through a multi-channel analog-to-digital conversion device;
(2) the controller processes the detected ultrasonic signals and displays waveforms, analyzes whether the detected ultrasonic signals contain detected characteristic information of the sample to be detected, and moves the sample to be detected to continue scanning if the detected ultrasonic signals do not contain the detected characteristic information of the sample to be detected; if so, determining a proper optical fiber array according to the approximate position and direction (detected initial characteristic information) of the detected characteristic information of the sample to be detected; the specific method comprises the following steps:
the method comprises the steps of analyzing the detected initial characteristic information of a sample to be detected by utilizing the prior art, matching the position, the shape and the size of the detected characteristic with the position of a fixed-point reinforcing point or the directional reinforcing direction of an optical fiber array, and finding out the best matching optical fiber array of the system, wherein the matching rule is to select the closest optical fiber array. For example, if the feature to be detected is analyzed in the initial inspection to be at a depth of 2.4cm from the vertical surface relative to the ultrasonic excitation point, and the positions of the fixed point enhancing points of the fiber array in the system are at a depth of 2cm and 3cm from the vertical surface, respectively, the fiber array for enhancing the ultrasonic intensity at a depth of 2cm from the vertical surface should be selected.
(3) Adjusting by using a conversion device of the optical fiber coupler, selecting a proper optical fiber coupler and an optical fiber array, and focusing the excitation laser to the corresponding optical fiber array to form a laser array pair; performing fixed-point or directional ultrasonic enhancement on the approximate position and direction (detected initial characteristic information) of the detected characteristic information of the sample to be detected;
the specific method for performing fixed-point ultrasonic enhancement on the approximate position and direction of the detected characteristic information of the sample to be detected comprises the following steps:
the method comprises the steps of firstly determining the distance and the angle of a position point needing to enhance the ultrasonic intensity relative to an ultrasonic source of laser irradiation on the surface of a sample to be detected, and then enabling the ultrasonic wave fronts generated by irradiation of optical fibers of an optical fiber array on the sample to arrive at the position point at the same time by calculating the length of the optical fibers required by the optical fiber array, so as to realize coherent enhancement of the ultrasonic wave at the determined position point. If the optical fiber array has m optical fibers, the lengths thereof are Li(i is more than or equal to 1 and less than or equal to m), and the distances between the corresponding laser irradiation points, namely the ultrasonic wave generation points and the position points needing to enhance the ultrasonic wave intensity are respectively Di(1. ltoreq. i. ltoreq.m), then:
wherein i is more than or equal to 1 and less than or equal to m-1, c is the propagation speed of the laser in the optical fiber, and v is the propagation speed of the used ultrasonic wave mode in the sample to be detected.
The specific method for performing directional ultrasonic enhancement on the approximate position and direction of the detected characteristic information of the sample to be detected comprises the following steps:
the method comprises the steps of firstly determining the angle of the direction needing to enhance the ultrasonic intensity relative to an ultrasonic source irradiated by laser on the surface of a sample to be detected, and then calculating the length of optical fibers required by an optical fiber array to enable the ultrasonic wave front generated by irradiating the optical fibers of the optical fiber array on the sample to be detected to arrive at the same time on a vertical plane of the direction, so as to realize the coherent enhancement of the ultrasonic wave in the determined direction. If the optical fiber array has m optical fibers, the lengths thereof are Li(i is more than or equal to 1 and less than or equal to m), and the distances between the corresponding laser irradiation point, namely the ultrasonic wave generation point, and a certain vertical plane in the direction needing to enhance the ultrasonic wave intensity are Si(1. ltoreq. i. ltoreq.m), then:
wherein i is more than or equal to 1 and less than or equal to m-1, c is the propagation speed of the laser in the optical fiber, and v is the propagation speed of the used ultrasonic wave mode in the sample to be detected.
(4) The enhanced detected characteristic information detected by the ultrasonic detection device is transmitted to a controller for analysis and processing through a multi-channel analog-to-digital conversion device;
(5) the controller analyzes whether the sample to be detected is scanned completely, and if the sample to be detected is scanned completely, the system finishes and stops working; and if not, performing plane scanning on the sample to be detected by moving the sample to be detected, and repeating the steps (1) to (5) to realize accurate measurement of the position, the shape and the size of the detected feature in the sample to be detected.
In summary, the present invention is a method for generating ultrasound control and performing fast non-destructive inspection of inspected features inside a material using a laser array. A converter device of an optical fiber coupler is utilized to quickly focus a laser light source generating ultrasonic waves into a matched optical fiber array according to an angle or a position point required to be enhanced by the ultrasonic waves of a detected sample, so that the quick beam control of the ultrasonic waves is realized. Specifically, when a sample is detected, ultrasonic waves are generated through an initially arranged optical fiber coupler, and according to the approximate information of the detected characteristic fed back by the detection device, the converter device of the optical fiber coupler can be used for quickly adjusting and focusing laser to an optical fiber array matched with the required length, so that the fixed point or directional strength of the generated ultrasonic waves is improved, and the position, the shape and the size of the detected characteristic in the sample are accurately measured. The invention improves the detection accuracy of unknown detected characteristics of the sample, provides a feasible scheme for rapidly and accurately measuring the detected characteristics of the sample, improves the efficiency of controlling ultrasonic wave beams in real time in laser ultrasonic detection, and realizes nondestructive detection by exciting the ultrasonic waves in a thermal-elastic mechanism in a non-contact manner.
Claims (3)
1. A laser array is to generating the nondestructive test system that supersound quick control, its characterized in that: the device comprises a laser generator, a laser transmission device, an ultrasonic detection device, a multi-channel analog-to-digital conversion device and a controller, wherein laser emitted by the laser generator is irradiated onto the surface of a sample to be detected through the laser transmission device, ultrasonic waves are generated under a thermal elastic mechanism, the ultrasonic waves propagated in the sample to be detected are detected by the ultrasonic detection device, information of the sample to be detected is transmitted to the controller through the multi-channel analog-to-digital conversion device, the detected initial characteristic information is analyzed, and the converted laser transmission device is fed back and adjusted;
the laser transmission device comprises a convex lens, a conversion device of an optical fiber coupler, an optical fiber coupler array, an optical fiber array and a focusing lens array, wherein the optical fiber coupler array is arranged on the conversion device of the optical fiber coupler and comprises at least two optical fiber couplers; the optical fiber array is at least two, and the focusing lens array comprises at least two focusing lenses; the optical fiber couplers, the optical fiber array and the focusing lens correspond to each other one by one, and laser emitted by the laser generator is focused on the optical fiber couplers through the convex lens, transmitted by the optical fiber array and then irradiated on the surface of a sample to be measured through the focusing lens;
the conversion device of the optical fiber coupler is a converter device which rotates in a +/-180-degree coaxial mode, and the angle of each rotation is determined according to the installed optical fiber couplerIf there are n fiber couplers, the angle of each turn is
Integral multiple of the optical fiber coupler, and the conversion device of the optical fiber coupler is connected with the controller for automatic conversion or manual conversion;
the number and distance of the optical fibers of the optical fiber array connected with each optical fiber coupler and the length collocation of the optical fibers are the same or different;
the nondestructive testing system also comprises a second stepping motor, the second stepping motor is connected with the conversion device of the optical fiber coupler, ultrasonic waves transmitted in the sample to be tested are detected by the ultrasonic testing device, and information of the sample to be tested is transmitted to the controller through the multi-channel analog-to-digital conversion equipment, so as to obtain the initial characteristic information to be tested; the controller controls the second stepping motor to adjust the conversion device of the conversion optical fiber coupler, and selects the corresponding optical fiber coupler of the optical fiber array, so that the strength of the generated ultrasonic wave at a fixed point or orientation is improved, and the accurate measurement of the detected characteristics in the sample to be detected is realized.
2. The system of claim 1, wherein the system comprises: the nondestructive testing system also comprises an electric control displacement platform and a first stepping motor, the sample to be tested is placed on the electric control displacement platform, the first stepping motor is connected with the controller, the controller controls the first stepping motor to rotate, and the movement of the sample to be tested is further controlled by controlling the electric control displacement platform.
3. A nondestructive testing method for a nondestructive testing system for generating ultrasonic fast control based on a laser array of any one of claims 1-2, comprising the steps of:
(1) firstly, laser excites ultrasonic waves in a sample to be detected through an initially arranged optical fiber coupler, and ultrasonic signals detected by an ultrasonic detection device are transmitted to a controller through a multi-channel analog-to-digital conversion device;
(2) the controller processes the ultrasonic signals and displays waveforms, analyzes whether the ultrasonic signals contain the detected initial characteristic information of the sample to be detected, and moves the sample to be detected to continue scanning if the ultrasonic signals do not contain the detected initial characteristic information of the sample to be detected; if so, determining a proper optical fiber array according to the detected initial characteristic information of the sample to be detected;
the method for determining the appropriate optical fiber array according to the detected initial characteristic information of the sample to be detected comprises the following steps:
analyzing the detected initial characteristic information of a sample to be detected by utilizing the prior art, and dematching the position, the shape and the size of the detected characteristic with the position or the directional enhancement direction of a fixed-point enhancement point of an optical fiber array to find out the best matching optical fiber array of the system, wherein the matching rule is to select the closest optical fiber array;
(3) adjusting by using an optical fiber coupler conversion device, selecting a proper optical fiber coupler and an optical fiber array, and focusing excitation laser to the corresponding optical fiber array to form a laser array; carrying out fixed-point or directional ultrasonic enhancement on the detected initial characteristic information of the sample to be detected;
the specific method for performing fixed-point ultrasonic enhancement on the detected initial characteristic information of the sample to be detected comprises the following steps: firstly, determining the distance and angle of a position point needing to enhance the ultrasonic intensity relative to an ultrasonic source irradiated by laser on the surface of a sample to be detected, and then calculating the length of an optical fiber required by an optical fiber array to enable the ultrasonic wave fronts generated by the irradiation of the optical fibers of the optical fiber array on the sample to arrive at the position point at the same time, so as to realize the coherent enhancement of the ultrasonic wave at the determined position point; the calculation formula is as follows:
if the optical fiber array has m optical fibers, the lengths thereof are LiI is 1, m, and the distances between the corresponding laser irradiation points, i.e. the ultrasonic wave generation points, and the position points where the ultrasonic wave intensity needs to be enhanced are respectively Di1, 1.. m, then:
wherein i is more than or equal to 1 and less than or equal to m-1, c is the propagation speed of laser in the optical fiber, and v is the propagation speed of the used ultrasonic wave mode in the sample to be detected;
the specific method for carrying out directional ultrasonic enhancement on the detected initial characteristic information of the sample to be detected comprises the following steps: firstly, determining the angle of the direction of ultrasonic intensity to be enhanced relative to an ultrasonic source irradiated on the surface of a sample to be detected by laser, and then calculating the length of optical fibers required by an optical fiber array to enable the ultrasonic wave front generated by the irradiation of the optical fibers of the optical fiber array on the sample to be detected to arrive at the same time on a vertical plane of the direction, thereby realizing the coherent enhancement of the ultrasonic wave in the determined direction; the calculation formula is as follows:
if the optical fiber array has m optical fibers, the lengths thereof are LiI is 1, m, and the distances between the corresponding laser irradiation point, i.e., the ultrasonic wave generation point, and a certain vertical plane in the direction in which the ultrasonic wave intensity needs to be enhanced are Si1, 1.. m, then:
wherein i is more than or equal to 1 and less than or equal to m-1, c is the propagation speed of laser in the optical fiber, and v is the propagation speed of the used ultrasonic wave mode in the sample to be detected;
(4) the enhanced detected characteristic information detected by the ultrasonic detection device is transmitted to a controller for analysis and processing through a multi-channel analog-to-digital conversion device;
(5) the controller analyzes whether the sample to be detected is scanned completely, and if the sample to be detected is scanned completely, the system finishes and stops working; and if not, performing plane scanning on the sample to be detected by moving the sample to be detected, and repeating the steps (1) to (5) to realize accurate measurement of the position, the shape and the size of the detected feature in the sample to be detected.
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