Atomic-force acoustic microscopy cantilever beam contact resonance frequency tracking system

A resonant frequency and tracking system technology, applied in scanning probe microscopy, measuring ultrasonic/sonic/infrasonic waves, measuring devices, etc., can solve the problems of slow imaging of atomic force microscope and slow contact with resonant frequency, and achieve fast automatic frequency The effectiveness of the tracking system

CN101839924AActive Publication Date: 2010-09-22BEIJING UNIV OF TECH
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2010-09-22

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Abstract

The invention discloses an atomic-force acoustic microscopy cantilever beam contact resonance frequency tracking system, which is mainly applied to rapidly acquiring the contact resonance frequency of an atomic-force acoustic microscopy cantilever beam so as to realize quick elastic modulus imaging of an atomic-force acoustic microscopy and belongs to the field of nondestructive testing. The system has the principle of controlling a voltage-controlled oscillator to output a sine voltage signal of the resonance center frequency so as to excite a piezoelectric sensor based on a voltage signal corresponding to the resonance peak of the atomic-force acoustic microscopy cantilever beam. The system mainly comprises an effective value DC conversion circuit (RMS-DC) which is connected with a photodiode detector of the atomic-force acoustic microscopy cantilever beam, a voltage-controlled oscillator (VCO) which is connected with the piezoelectric sensor of the atomic-force acoustic microscopy,and a DSP control panel for processing the frequency signals. The DSP control panel controls the VCO to output the sine voltage signal of the resonance center frequency so as to excite the piezoelectric sensor and obtain a resonance curve. Therefore, the center frequency of the resonance curve is obtained and a rapid automatic frequency tracking system is realized.
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Description

technical field

[0001] The AFM cantilever contact resonance frequency tracking system is mainly used to quickly obtain the contact resonance frequency of the AFM cantilever, and then realize the rapid elastic modulus imaging of the AFM, which belongs to the field of non-destructive testing. Background technique

[0002] The atomic force acoustic microscope (AFAM) technology excites the high-order vibration mode of the cantilever beam by making the cantilever beam of the atomic force microscope or the test object vibrate ultrasonically. Accurate determination of the drift of high-order resonance frequencies can well reflect the local mechanical properties of the specimen surface, such as contact stiffness, elastic constant, and near-surface defects. This technology has a very high lateral resolution (less than 10nm), which is not only suitable for the detection of surface and near-surface defects of electronic packaging solder joints, but also can measure the elastic properti...

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Embodiment Construction

[0015] The present invention will be further described through specific embodiments below in conjunction with the accompanying drawings. The following embodiments are only descriptive, not restrictive, and cannot be used to limit the protection scope of the present invention. The overall structural block diagram of the present embodiment is as figure 1 As shown, the specific working process is as follows:

[0016] 1) The frequency sweep signal is sent out from the DSP control board, and the VCO is controlled to generate an amplitude-adjustable frequency sweep sine wave, which is transmitted to the piezoelectric sensor, and the sample is placed on the piezoelectric sensor.

[0017] 2) The signal penetrates the sample and is received by the cantilever in the AFM. When the probe on the cantilever beam touches the sample, this weak vibration propagates through the probe-sample coupling and excites the cantilever to vibrate. A photodiode detector detects the vibration amplitude o...