Method and apparatus for resonant frequency identification through out-of-plane displacement detection
First Claim
1. An apparatus for out-of-plane displacement detection and resonant frequency identification, comprising:
- a central control unit;
a synchronous control unit, coupled to the central control unit for generating the first, second and third control signals synchronously with the control signal of the central control unit;
a vibration-driving unit for carrying and vibrating the sample upon receiving the first control signal;
a light-emitting unit for generating a stroboscopic flash upon receiving the second control signal; and
an image acquisition unit for acquiring a series of interference images from the sample upon receiving the third control signal, and transmitting the interference image acquired to the central control unit,wherein the central control unit receives and processes the series of interference images by using image-filtering, extracts frequency-domain information from the series of processed interference images to calculate a fringe density index of each processed interference image, and detects the out-of-plane displacement of the vibrating sample from the fringe density indexes calculated.
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Abstract
A method for out-of-plane displacement detection is disclosed. The out-of-plane displacement is detected by analyzing all the fringe density indexes calculated using the frequency-domain information extracted from a series of interference images of the sample vibrating at different frequencies. The present invention further discloses a method and an apparatus for resonant frequency identification by detecting the peak value of all the fringe indexes calculated at different scanning frequencies. With the identified resonant frequency, the full-field vibratory surface profile of the sample in various resonance modes can be reconstructed.
18 Citations
16 Claims
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1. An apparatus for out-of-plane displacement detection and resonant frequency identification, comprising:
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a central control unit; a synchronous control unit, coupled to the central control unit for generating the first, second and third control signals synchronously with the control signal of the central control unit; a vibration-driving unit for carrying and vibrating the sample upon receiving the first control signal; a light-emitting unit for generating a stroboscopic flash upon receiving the second control signal; and an image acquisition unit for acquiring a series of interference images from the sample upon receiving the third control signal, and transmitting the interference image acquired to the central control unit, wherein the central control unit receives and processes the series of interference images by using image-filtering, extracts frequency-domain information from the series of processed interference images to calculate a fringe density index of each processed interference image, and detects the out-of-plane displacement of the vibrating sample from the fringe density indexes calculated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for out-of-plane displacement detection and resonant frequency identification, comprising:
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a central control unit; a synchronous control unit, coupled to the central control unit for generating the first, second and third control signals synchronously with the control signal of the central control unit; a vibration-driving unit for carrying and vibrating the sample upon receiving the first control signal; a light-emitting unit for generating a stroboscopic flash upon receiving the second control signal; and an image acquisition unit for acquiring a series of interference images from the sample upon receiving the third control signal, and transmitting the interference image acquired to the central control unit; wherein the central control unit receives and processes the series of interference images by using image-filtering, extracts frequency-domain information from the series of processed interference images to calculate a fringe density index of each processed interference image, and detects a peak value by analyzing all the fringe density indexes calculated to identify a resonant frequency of the vibrating sample. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification