Multi-channel ultrasonic microscope

Abstract

The invention discloses a multichannel ultrasonic microscope, and relates to the technical field of ultrasonic nondestructive testing. Comprising a plurality of ultrasonic transducers which are clamped on a scanning table; a target object is placed in the scanning table water tank; the scanning table drives the plurality of ultrasonic transducers to scan a target object according to a preset path at the same time, and generates a position trigger signal according to a preset position; the cooperative trigger receives the position trigger signals and generates a plurality of synchronous position trigger signals; after the synchronous position trigger signal is received, the pulse transceiver sends an excitation signal to the ultrasonic transducer and receives and conditions an ultrasonic reflection / transmission signal; the ultrasonic transducer transmits an ultrasonic signal to a to-be-imaged target object and converts reflected / transmitted ultrasonic waves into an electric signal; the signal collecting and preprocessing module collects and processes the electric signals transmitted by the pulse transceiver and then transmits the electric signals to the computer. And the computer images the to-be-imaged target object according to the processed signal. According to the invention, efficient ultrasonic microscopic imaging is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrasonic nondestructive testing, and particularly to a multi-channel ultrasonic microscope. Background Art

[0002] Ultrasonic microscopes have a wide range of applications in the fields of semiconductors, integrated circuits, materials, aerospace, machinery, and biology. Ultrasonic microscopes can non-destructively and finely observe the internal, subsurface, and surface structures of materials at the highest sub-micron level resolution, and can also achieve high-resolution imaging measurement of material mechanical parameters based on the acoustoelastic principle. At present, the development of multi-channel ultrasonic microscopes and single-channel ultrasonic microscopes has been realized, but generally, computer triggering, direct uploading of ultrasonic signals to the computer for processing, and the "servo motor + lead screw" scheme for the vertical focusing axis are adopted, resulting in problems such as limited scanning speed, poor module synchronization, limited applicable specimen surface types, and inaccurate focusing, which in turn affect the efficiency, accuracy, and applicability of the entire instrument. Summary of the Invention

[0003] The purpose of the present invention is to provide a multi-channel ultrasonic microscope that can achieve high-efficiency imaging.

[0004] To achieve the above purpose, the present invention provides the following solution: A multi-channel ultrasonic microscope includes: a computer, a scanning stage, a plurality of ultrasonic transducers, a pulse transceiver, a signal acquisition and preprocessing module, and a cooperative trigger; The scanning stage includes a water tank and a multi-coordinate moving stage; the water tank is filled with a water medium for transmitting ultrasonic waves; the target object to be imaged is arranged in the water tank; A plurality of ultrasonic transducers are all arranged on the multi-coordinate moving stage; the multi-coordinate moving stage is used to drive the plurality of ultrasonic transducers to move along a preset path, and generate a position trigger signal when the plurality of ultrasonic transducers all move to corresponding preset positions; The cooperative trigger is respectively connected to the scanning stage, the signal acquisition and preprocessing module, and the pulse transceiver; the cooperative trigger is used to receive the position trigger signal, generate a plurality of synchronous position trigger signals from the position trigger signal, and send each of the synchronous position trigger signals to the signal acquisition and preprocessing module and the pulse transceiver; A plurality of the ultrasonic transducers are all connected to the pulse transceiver; a plurality of the ultrasonic transducers are all used to emit ultrasonic signals to the target object to be imaged after receiving an excitation signal, receive the ultrasonic waves reflected / transmitted by the target object to be imaged, and convert the ultrasonic waves into electrical signals; The pulse transceiver is connected to the signal acquisition and preprocessing module; the pulse transceiver is configured to send an excitation signal to a plurality of the ultrasonic transducers after receiving the synchronous position trigger signal, and receive the electrical signals sent by the plurality of the ultrasonic transducers, and condition the electrical signals and then send them to the signal acquisition and preprocessing module; The signal acquisition and preprocessing module is connected to the computer; the signal acquisition and preprocessing module is configured to acquire the electrical signals after receiving the synchronous position trigger signal, and process the electrical signals, and transmit the processed signals to the computer; The computer is used for controlling each module, and determining the imaging of the target object to be imaged according to the processed signals.

[0005] Optionally, the scanning table is connected to the computer; the computer is used for setting the preset path and the preset position of the scanning table.

[0006] Optionally, the multi-coordinate moving table includes a moving mechanism and an autofocus device; The autofocus device is arranged on the moving mechanism; the moving mechanism is used for driving the autofocus device to move in the horizontal direction of the preset plane; The autofocus device includes a plurality of focusing axes perpendicular to the preset plane; the focusing axes are arranged in one-to-one correspondence with the ultrasonic transducers; the plurality of ultrasonic transducers are arranged on the corresponding focusing axes; the focusing axes are used for driving the corresponding ultrasonic transducers to move in the vertical direction; the vertical direction is perpendicular to the preset plane.

[0007] Optionally, the scanning table further includes a grating ruler; the grating ruler is used for determining the coordinates of the plurality of ultrasonic transducers.

[0008] Optionally, a display terminal and a control terminal are further included.

[0009] Optionally, processing the electrical signals and transmitting the processed signals to the computer specifically includes: Converting the electrical signals into digital signals, and transmitting the digital signals to the computer; Or: Converting the electrical signals into digital signals, extracting the eigenvalue of the digital signals, and transmitting the eigenvalue to the computer.

[0010] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention: The multi-channel ultrasonic microscope (ultrasonic microscope / ultrasonic scanning microscope) provided by the present invention is composed of a multi-module collaborative trigger, a multi-channel autofocus module, a multi-channel digital acquisition and preprocessing card, a multi-channel ultrasonic pulse transceiver, an ultrasonic immersion focusing transducer, a scanning stage, a computer, software, etc. It is an ultrasonic microscope product that can achieve multi-channel autofocus, signal preprocessing, and synchronous scanning imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0012] Figure 1 It is a schematic connection structure diagram of a four-channel ultrasonic microscope provided in Embodiment 1 of the present invention; Figure 2 It is a schematic external structure diagram of a four-channel ultrasonic microscope provided in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0014] The purpose of the present invention is to provide a multi-channel ultrasonic microscope that can achieve high-efficiency imaging.

[0015] In the present invention, the solutions of "position trigger + collaborative trigger", "multi-channel", "signal acquisition and preprocessing", and "linear motor independent follow-up focusing" are jointly adopted, and an ultrasonic microscope that can achieve high-efficiency imaging, high-precision focusing, and imaging can be realized.

[0016] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0017] Embodiment 1 As Figure 1 and Figure 2 shown, the multi-channel ultrasonic microscope in this embodiment includes: a computer, a scanning stage, multiple ultrasonic transducers, a pulse transceiver, a signal acquisition and preprocessing module, and a collaborative trigger.

[0018] The scanning table includes a water tank and a multi-coordinate moving table; a water medium for transmitting ultrasonic waves is contained in the water tank; the object to be imaged is arranged in the water tank.

[0019] A plurality of ultrasonic transducers are all arranged on the multi-coordinate moving table; the multi-coordinate moving table is used to drive the plurality of ultrasonic transducers to move along a preset path, and generate a position trigger signal when the plurality of ultrasonic transducers all move to corresponding preset positions.

[0020] The cooperative trigger is respectively connected to the scanning table, the signal acquisition and preprocessing module, and the pulse transceiver; the cooperative trigger is used to receive the position trigger signal, generate a plurality of synchronous position trigger signals from the position trigger signal, and send each of the synchronous position trigger signals to the signal acquisition and preprocessing module and the pulse transceiver.

[0021] The plurality of ultrasonic transducers are all connected to the pulse transceiver; the plurality of ultrasonic transducers are all used to emit ultrasonic signals to the object to be imaged after receiving an excitation signal, receive the ultrasonic waves reflected / transmitted by the object to be imaged, and convert the ultrasonic waves into electrical signals.

[0022] The pulse transceiver is connected to the signal acquisition and preprocessing module; the pulse transceiver is used to send an excitation signal to the plurality of ultrasonic transducers after receiving the synchronous position trigger signal, receive the electrical signals sent by the plurality of ultrasonic transducers, and send the conditioned electrical signals to the signal acquisition and preprocessing module.

[0023] The signal acquisition and preprocessing module is connected to the computer; the signal acquisition and preprocessing module is used to acquire the electrical signals after receiving the synchronous position trigger signal, process the electrical signals, and transmit the processed signals to the computer.

[0024] The computer is used for controlling each module, and determining the imaging of the object to be imaged according to the processed signals.

[0025] As a specific implementation manner, the scanning table is connected to the computer; the computer is used to set the preset path and the preset positions of the scanning table. The multi-coordinate moving table includes a moving mechanism and an auto-focus device. The auto-focus device is arranged on the moving mechanism; the moving mechanism is used to drive the auto-focus device to move in the horizontal direction of a preset plane. The auto-focus device includes a plurality of focusing axes perpendicular to the preset plane; the focusing axes are arranged in one-to-one correspondence with the ultrasonic transducers; the plurality of ultrasonic transducers are arranged on the corresponding focusing axes; the focusing axes are used to drive the corresponding ultrasonic transducers to move in the vertical direction; the vertical direction is perpendicular to the preset plane.

[0026] As a specific implementation manner, the scanning stage further includes a grating scale, a display terminal, and a control terminal; the grating scale is used to determine the coordinates of the plurality of ultrasonic transducers. Both the display terminal and the control terminal are connected to the computer.

[0027] As a specific implementation manner, the signal acquisition and preprocessing module processes the electrical signal and transmits the processed signal to the computer, specifically including two methods: First, convert the electrical signal into a digital signal and transmit the digital signal to the computer. Specifically, the signal acquisition and preprocessing module is an analog-to-digital conversion module.

[0028] Second, convert the electrical signal into a digital signal, extract the eigenvalue of the digital signal, and transmit the eigenvalue to the computer.

[0029] The working process of the multi-channel ultrasonic microscope provided by the present invention is as follows: A plurality of ultrasonic transducers are placed on the scanning stage. The scanning stage drives the ultrasonic transducers to scan along the path set by the computer. After reaching a set position, a position trigger signal is output and the coordinate value is fed back to the computer; the cooperative trigger receives the position trigger signal sent by the scanning stage, generates a plurality of synchronous position trigger signals from the position trigger signal, and sends each of the synchronous position trigger signals to the signal acquisition and preprocessing module and the pulse transceiver. After receiving the synchronous position trigger signal, the pulse transceiver sends an excitation signal to the ultrasonic transducer. The ultrasonic transducer receives the electrical signal and, by applying the inverse piezoelectric effect, converts it into vibration, that is, an acoustic wave signal, to excite ultrasonic waves, which hit the object to be measured. The ultrasonic waves are reflected / transmitted, and the reflected / transmitted ultrasonic waves are received by the ultrasonic transducer. By applying the piezoelectric effect, the received ultrasonic waves are converted into electrical signals, and the electrical signals are received by the pulse transceiver. This electrical signal is an analog signal. The pulse transceiver conditions the electrical signal and sends the conditioned analog electrical signal to the signal acquisition and preprocessing module. The signal acquisition and preprocessing module converts the conditioned analog electrical signal into a digital signal or extracts the eigenvalue of the digital signal. The signal acquisition and preprocessing module outputs the digital signal or the eigenvalue according to actual needs, and sends the output result of the signal acquisition and preprocessing module to the computer. The computer determines the imaging of the object to be imaged target according to the output result of the signal acquisition and preprocessing module and the spatial coordinates fed back by the scanning stage.

[0030] In practical applications, as Figure 1 shown, the computer is connected to the scanning stage, the signal acquisition and preprocessing module signal acquisition and preprocessing, the pulse transceiver, the display terminal, the control terminal, and the cooperative trigger cooperative trigger.

[0031] The scanning stage carries an ultrasonic transducer through a mechanical fixture, and at the same time connects to a cooperative trigger, which outputs a position trigger signal; the cooperative trigger performs real-time conversion on the position trigger signal, divides the single-channel position trigger signal fed back by the scanning stage into multiple channels, and outputs them to the signal acquisition and preprocessing module and the pulse transceiver respectively. The pulse transceiver is connected to the ultrasonic transducer and the signal acquisition and preprocessing module.

[0032] In the present invention, the computer belongs to the central control and processing core of the system. First, it controls the scanning stage, the signal acquisition and preprocessing module, and the pulse transceiver. Among them, for the scanning stage, according to the scanning requirements of the test piece, it controls the scanning range, scanning mode (such as A-scan, B-scan, C-scan, X-scan, Z-scan, array scan, through scan, circular tube scan, etc.), trigger step, scanning speed, surface / internal focusing, defect quantification, edge determination, and imaging mode (peak imaging, frequency domain imaging, phase imaging, time-of-flight imaging, three-dimensional imaging), etc.; for the signal acquisition and preprocessing module, it controls the switches of its various channels, sampling rate, number of sampling points, range, and signal preprocessing function (in-card detection of characteristics such as the peak value, frequency point amplitude, phase value, and time-of-flight of the ultrasonic signal) switches, etc.; for the pulse transceiver, it controls its trigger mode, repetition frequency, transmission / reflection working mode, signal filtering start and end frequencies, signal gain, excitation voltage, impedance value, etc.

[0033] Secondly, the computer processes the signals and performs imaging and analysis through built-in algorithms. It receives in real time the spatio-temporal signals fed back by the scanning stage and the signal acquisition and preprocessing module in real time, that is, the coordinates of each channel of the ultrasonic transducer fed back by the scanning stage and the time domain / characteristic signals of each channel fed back by the signal acquisition and preprocessing module. After fusing the real-time spatio-temporal signals of the above-mentioned channels, multi-channel real-time scanning imaging can be realized.

[0034] Finally, the human-computer interaction interface of the computer is displayed by a display terminal, and the human-computer interaction is realized by a control terminal.

[0035] The scanning stage contains multiple vertical focusing axes, each vertical focusing axis holds an ultrasonic transducer, performs three-dimensional coordinate scanning according to the planned path, and in real time feeds back the coordinates of the current ultrasonic transducer to the computer and the motion control card inside the scanning stage through the built-in grating scale system. When the motion control card finds that it reaches the sampling point coordinates specified by the computer, it outputs a trigger signal to the cooperative trigger once.

[0036] The cooperative trigger contains multiple channels, and the impedance of each channel is matched with the connected module. It is used to convert the differential position trigger signal output by the scanning stage into multiple voltage trigger signals in real time, and through conditioning, make the phases of the multiple trigger signals consistent and the amplitudes meet the requirements of the connected module, and output them to the signal acquisition and preprocessing module and the pulse transceiver, and trigger.

[0037] The pulse transceiver contains multiple channels. After receiving a trigger signal, it operates with the parameters set by the computer, applies a voltage pulse to the ultrasonic transducer to excite it to generate ultrasonic waves, conditions the ultrasonic echo signal received by the ultrasonic transducer, and sends the conditioned analog signal to the signal acquisition and preprocessing module.

[0038] The ultrasonic transducer is used to test the workpiece to be measured. Using the piezoelectric effect, it converts mechanical energy into electrical energy to receive ultrasonic echoes; using the inverse piezoelectric effect, it converts electrical energy into mechanical energy to excite ultrasonic waves.

[0039] The signal acquisition and preprocessing module contains multiple channels. After receiving a trigger signal, it operates with the parameters set by the computer, receives the ultrasonic echo analog signal from the pulse transceiver, converts it into a digital signal, and outputs it to the computer; when the computer sets its signal preprocessing function to be enabled, it extracts in real time the characteristic values such as the peak value, frequency point amplitude, phase value, and flight time of the digital signal, and outputs them to the computer.

[0040] The present invention has the following technical effects: 1. High scanning imaging speed and high precision.

[0041] (1) The scanning stage directly triggers each module in a position-triggered manner. Traditional ultrasonic microscopes generally adopt a computer-triggered mode, that is, the coordinates of the scanning stage are fed back to the computer, and then the computer controls each module to trigger. The disadvantages of this method are: poor real-time performance, and it is easy to have the working asynchronism of each module, resulting in the asynchronism between the transducer coordinates and the ultrasonic characteristic signals, causing problems such as image pixel point loss and dislocation, and ultimately leading to image distortion, which is difficult to meet the requirements of high resolution and high-speed scanning. In the "position trigger + cooperative trigger" scheme adopted in the present invention, the position trigger signal is directly sent from the scanning stage to each module through the cooperative trigger, with good real-time performance, which can ensure that each module still works synchronously under high-speed scanning and achieve high-precision imaging.

[0042] (2) The scanning stage contains multiple vertical focusing axes, and the signal acquisition and preprocessing module, the pulse transceiver, and the cooperative trigger all contain multiple channels, which can realize simultaneous scanning imaging of multiple specimens, and can also realize multi-channel scanning imaging stitching of a large specimen; improving the scanning imaging efficiency.

[0043] (3)The signal acquisition and preprocessing module has the function of in-card signal preprocessing, and can extract signal characteristic values in the card through a field programmable gate array or the like. The data volume of the signal characteristic values is extremely small and can be transmitted to the computer in real time for imaging. This avoids the problems caused by the traditional ultrasonic microscope that needs to upload the original signal data to the computer and then extract the signal characteristic values by the computer: when performing high-speed and high-precision scanning, the computer processes a large amount of original data slowly, resulting in the accumulation and overflow of data in the on-board memory of the acquisition card, and ultimately unable to achieve high-speed and high-precision scanning.

[0044] 2. High-precision real-time scanning imaging of complex curved specimens.

[0045] All vertical focusing axes of the scanning stage adopt a linear motor solution, which are independent of each other and are respectively connected to different channels of the motion controller and the driver. During scanning, they independently follow the focus with the change of the scanned curved surface. During multi-channel scanning, real-time scanning imaging of complex curved specimens can be achieved. The traditional ultrasonic microscope uses a "servo motor + lead screw" solution for the vertical focusing axis, with low precision and slow speed, and it is difficult to meet the high-speed and accurate focusing requirements in the ultra-high-frequency ultrasonic microscopy ultra-precision scanning, resulting in slow imaging and low image precision.

[0046] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should all be considered as the scope described in this specification.

[0047] In this article, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A multi-channel ultrasonic microscope, characterized in that, Comprising: A computer, a scanning table, a plurality of ultrasonic transducers, a pulse transceiver, a signal acquisition and preprocessing module, and a collaborative trigger; The scanning table includes a water tank and a multi-coordinate moving table; a water medium for transmitting ultrasonic waves is contained in the water tank; the object to be imaged is disposed in the water tank; The plurality of ultrasonic transducers are all disposed on the multi-coordinate moving table; the multi-coordinate moving table is used to drive the plurality of ultrasonic transducers to move along a preset path, and generate a position trigger signal when the plurality of ultrasonic transducers all move to corresponding preset positions; The collaborative trigger is respectively connected to the scanning table, the signal acquisition and preprocessing module, and the pulse transceiver; The collaborative trigger is used to receive the position trigger signal, generate a plurality of synchronous position trigger signals from the position trigger signal, and send each of the synchronous position trigger signals to the signal acquisition and preprocessing module and the pulse transceiver; The plurality of ultrasonic transducers are all connected to the pulse transceiver; the plurality of ultrasonic transducers are all used to emit ultrasonic signals to the object to be imaged after receiving an excitation signal, receive the ultrasonic waves reflected / transmitted by the object to be imaged, and convert the ultrasonic waves into electrical signals; The pulse transceiver is connected to the signal acquisition and preprocessing module; the pulse transceiver is used to send an excitation signal to the plurality of ultrasonic transducers after receiving the synchronous position trigger signal, receive the electrical signals sent by the plurality of ultrasonic transducers, and send the conditioned electrical signals to the signal acquisition and preprocessing module; The signal acquisition and preprocessing module is connected to the computer; the signal acquisition and preprocessing module is used to acquire the electrical signals after receiving the synchronous position trigger signal, process the electrical signals, and transmit the processed signals to the computer; The computer is used for controlling each module, and determining the imaging of the object to be imaged according to the processed signals.

2. The multi-channel ultrasonic microscope according to claim 1, characterized in that, The scanning table is connected to the computer; the computer is used to set the preset path and the preset positions of the scanning table.

3. The multi-channel ultrasonic microscope according to claim 1, characterized in that The multi-coordinate moving table includes a motion mechanism and an autofocus device; The autofocus device is disposed on the motion mechanism; the motion mechanism is used to drive the autofocus device to move in the horizontal direction of a preset plane; The autofocus device includes a plurality of focus axes perpendicular to the preset plane; the focus axes are arranged in one-to-one correspondence with the ultrasonic transducers; the plurality of ultrasonic transducers are disposed on the corresponding focus axes; the focus axes are used to drive the corresponding ultrasonic transducers to move in the vertical direction; the vertical direction is perpendicular to the preset plane.

4. The multi-channel ultrasonic microscope according to claim 3, wherein, The scanning table further includes a grating scale; the grating scale is used to determine the coordinates of the plurality of ultrasonic transducers.

5. The multi-channel ultrasonic microscope according to claim 1, characterized in that Also included is a display terminal and a control terminal.

6. The multi-channel ultrasonic microscope according to claim 1, characterized in that, Processing the electrical signals and transmitting the processed signals to the computer specifically includes: Converting the electrical signals into digital signals and transmitting the digital signals to the computer; Or: Convert the electrical signal into a digital signal, extract the characteristic values of the digital signal, and transmit the characteristic values to the computer.

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