Method and apparatus for remote measurement of vibration and properties of objects

Abstract

A method and apparatus is provided which employs phase or amplitude modulated electromagnetic probing waves (in optical or microwave frequency ranges or both) emitted toward a vibrating object. The optical and/or microwave probing signals remotely irradiate an object of interest. The object reflects and/or scatters the probing wave toward to a receiver. The reflected/scattered modulated signal is received with a remote sensor (receiver). Vibration causes additional phase modulation to the probing wave. At the receiving end, the signal is demodulated to extract and analyze the vibration waveform. The present invention can be utilized for nondestructive testing, monitoring of technological processes, structural integrity, noise and vibration control, mine detection, etc.

1 . An electromagnetic wave vibrometer apparatus comprising: 
 a signal generator for generating an optical signal;    an amplitude modulator for amplitude modulating the optical signal with a microwave frequency electromagnetic signal to produce an amplitude modulated optical signal;    a first transmitter for transmitting the amplitude modulated optical signal at a vibrating object;    a first receiver for receiving a reflected amplitude modulated optical signal from the vibrating object;    a demodulator for demodulating the reflected amplitude modulated optical signal to produce a demodulated signal; and    a signal processor for extracting and analyzing a vibration waveform from the demodulated signal.    
   
   
       2 - 5 . (canceled)  
   
   
       6 . The apparatus of  claim 1 , wherein the optical signal is modulated by the same frequency as the microwave frequency electromagnetic signal.  
   
   
       7 . The apparatus of  claim 1  wherein the signal generator further comprises a laser signal source.  
   
   
       8 . The apparatus of  claim 1  wherein the signal generator further comprises an LED signal source.  
   
   
       9 . The apparatus of  claim 1  further comprising a second vibration receiver mounted with the first receiver for compensation for unwanted background or coupled vibration.  
   
   
       10 . The apparatus of  claim 9  further comprising a second vibration transmitter mounted with the first receiver for calibration of the apparatus to determine an angle of reflection.  
   
   
       11 . An apparatus for remotely measuring properties of an object comprising: 
 a signal generator for generating an optical signal;    an amplitude modulator for amplitude modulating the optical signal with a microwave frequency electromagnetic signal to produce an amplitude modulated optical signal;    a first transmitter for transmitting the amplitude modulated optical signal at an object;    means for vibrating the object to modulate the amplitude modulated optical signal transmitted at the object;    a first receiver for receiving a reflected amplitude modulated optical signal from the object;    a demodulator for demodulating the reflected amplitude modulated optical signal using the modulating signal to produce a demodulated signal; and    a signal processor for extracting and analyzing a vibration waveform from the demodulated signal.    
   
   
       12 - 15 . (canceled)  
   
   
       16 . The apparatus of  claim 11  wherein the signal is modulated by the same frequency as the microwave frequency electromagnetic signal.  
   
   
       17 . The apparatus of  claim 11  wherein the signal generator further comprises a laser signal source.  
   
   
       18 . The apparatus of  claim 11  wherein the signal generator further comprises an LED signal source.  
   
   
       19 . The apparatus of  claim 11  further comprising a second vibration receiver mounted with the first receiver for compensation for unwanted background or coupled vibration.  
   
   
       20 . The apparatus of  claim 19  further comprising a second vibration transmitter mounted with the first receiver for calibration of the apparatus to determine an angle of reflection.  
   
   
       21 . A method of remotely measuring vibration comprising: 
 generating an optical signal;    amplitude modulating the optical signal with a microwave frequency electromagnetic signal to produce an amplitude modulated optical signal;    transmitting the amplitude modulated optical signal at a vibrating object;    receiving a reflected amplitude modulated optical signal from the vibrating object;    demodulating the reflected amplitude modulated signal using the microwave frequency electromagnetic signal; and    analyzing the demodulated signal.    
   
   
       22 - 25 . (canceled)  
   
   
       26 . The apparatus of  claim 21 , further comprising modulating the optical signal at the same frequency as the microwave frequency electromagnetic signal.  
   
   
       27 . The method of  claim 21  further comprising generating the optical signal using a laser or a low coherent laser diode.  
   
   
       28 . The method of  claim 21  further comprising generating the optical signal using an LED.  
   
   
       29 . The method of  claim 21  further comprising compensating for vibration errors by determining vibration displacements of the transmitter and receiver.  
   
   
       30 . The method of  claim 30  further comprising compensating for unwanted background or coupled vibration using a second vibration receiver mounted with the first receiver.  
   
   
       31 . The method of  claim 30  further comprising calibrating the vibrometer to determine an angle of reflection using a second vibration transmitter mounted with the first receiver.  
   
   
       32 . A method for remotely determining properties of an object comprising: 
 amplitude modulating an optical signal with a microwave frequency electromagnetic signal to produce an amplitude modulated optical signal;    transmitting the amplitude modulated optical signal at an object;    vibrating the object;    receiving reflected amplitude modulated optical signals from the vibrating object; and    processing the reflected amplitude modulated optical signals to extract information about the properties of the object.    
   
   
       33 - 36 . (canceled)  
   
   
       37 . The method of  claim 32  further comprising modulating the optical signal at the same frequency as the microwave frequency electromagnetic signal.  
   
   
       38 . The method of  claim 32  further comprising generating the optical signal using a laser or a low coherent laser diode.  
   
   
       39 . The method of  claim 32  further comprising generating the optical signal using an LED.  
   
   
       40 . The method of  claim 32  further comprising splitting the amplitude modulated optical signal into first and second signals and transmitting the second signal to a demodulator for comparing the second signal with the received reflected amplitude modulated optical signal.  
   
   
       41 . The method of  claim 32  further comprising compensating for vibration errors by determining vibration displacements of the transmitter and receiver.  
   
   
       42 . The method of  claim 41  further comprising compensating for unwanted background or coupled vibration by providing a second vibration receiver mounted with the first receiver.  
   
   
       43 . The method of  claim 42  further comprising calibrating the vibrometer to determine an angle of reflection by providing a second vibration transmitter mounted with the first receiver.  
   
   
       44 . The apparatus of  claim 1 , wherein the amplitude modulated optical signal is modulated in the GHz range.  
   
   
       45 . The apparatus of  claim 11 , wherein the amplitude modulated optical signal is modulated in the GHz range.  
   
   
       46 . The method of  claim 21 , wherein the step of amplitude modulating the optical signal comprises amplitude modulating the optical signal in the GHz range.  
   
   
       47 . The apparatus of  claim 1 , wherein the optical signal is non-coherent.  
   
   
       48 . The apparatus of  claim 11 , wherein the optical signal is non-coherent.  
   
   
       49 . The method of  claim 21 , wherein the step of generating the optical signal comprises comprising generating a non-coherent optical signal.