Method and apparatus for real-time vibration imaging
A system and method for detecting vibration information by receiving electromagnetic radiation reflected or emitted from a target object at a photodetector array to provide real-time imaging of the target object. The detected radiation may be visible light, infrared or ultraviolet radiation, and/or of other desired frequency ranges. The detected radiation is AC-coupled to isolate components relating to oscillations of the target object from components relating to ambient radiation, e.g. background sunlight, and is digitized, stored, and subjected to processing such as a Fourier transform to generate outputs representative of frequencies of oscillation, which can be used for analysis of the target object.
1. A system for detecting a light signal relating to the vibration of a target object, including:
an array of light amplitude modulation detectors, each detector in the array configured to receive a light signal from a corresponding region of the target object and to generate an output representing the received signal;
a plurality of filters, each filter configured to receive the output from one of the detectors and to generate from the received output at least one filtered signal relating to a vibration of the corresponding region of the target object; and
a processing module configured to generate from each of the filtered light signals a processed output representing the vibration relating to the corresponding region.
2. The system of claim 1 , wherein the light signal relates to an oscillation of the target object.
3. The system of claim 1 , wherein the light signal relates to a transient pulse of the target object.
4. The system of claim 1 , wherein at least a portion of the received signals include electromagnetic radiation reflected from the corresponding regions of the target object.
5. The system of claim 4 , wherein the reflected radiation includes visible radiation.
6. The system of claim 4 , wherein the reflected radiation includes infrared radiation.
7. The system of claim 4 , wherein the reflected radiation includes ultraviolet radiation.
8. The system of claim 1 , wherein at least a portion of the received signals include electromagnetic radiation emitted from the corresponding regions of the target object.
9. The system of claim 8 , wherein the emitted radiation includes thermal IR radiation.
10. The system of claim 8 , wherein the emitted radiation includes fluorescent radiation.
11. The system of claim 1 , wherein the filters are configured to AC couple the outputs to generate filtered signals from which DC components have been at least partly removed.
12. The system of claim 1 , wherein the processing module is configured to generate frequency information for each of the filtered signals.
13. The system of claim 12 , wherein the processing module is configured to generate, for each filtered signal, a contrast signal representing a contrast attribute of the corresponding filtered signal.
14. The system of claim 13 , wherein the processing module is configured to correlate the contrast attributes with the frequency information.
15. The system of claim 14 , wherein the processing module is configured to generate an output representing a plot of contrast distribution across the array of detectors, the contrast distribution being associated with a given frequency.
16. The system of claim 1 , wherein the detectors are configured to sample received signals at a predetermined rate.
17. The system of claim 16 , wherein the predetermined rate is fixed.
18. The system of claim 16 , wherein the predetermined rate is variable.
19. The system of claim 15 , wherein the processing module is configured to generate the processed outputs at predetermined regular time intervals, the time intervals being of a length that is greater than a time interval corresponding to the predetermined sampling rate.
20. The system of claim 4 , wherein at least a portion of the reflected signals are due to naturally occurring ambient electromagnetic radiation.
21. The system of claim 4 , wherein at least a portion of the reflected signals are due to artificially generated electromagnetic radiation directed at the target object.
22. The system of claim 4 , wherein the reflected electromagnetic radiation is at least in part from a collimated radiation source.
23. The system of claim 4 , wherein the reflected electromagnetic radiation is at least in part from a coherent radiation source.
24. The system of claim 1 , further including an apparatus configured to induce vibrations in the target object.
25. The system of claim 1 , wherein the detectors comprise photodiodes.
26. The system of claim 1 , wherein the detectors comprise CMOS detectors.
27. The system of claim 1 , including an optical filter positioned between the array of the detectors and the target object.
28. The system of claim 1 , wherein the processing module is configured to generate a contrast signal corresponding to the vibration of each corresponding region.
29. The system of claim 28 , further including a visual output device coupled to the processing module and configured to generate a representation of the target object superimposed with the contrast signals correlated with their respective corresponding regions.
30. The system of claim 1 , wherein the processing module is configured to generate a temporal spectral signal corresponding to the vibration of each corresponding region.
31. The system of claim 28 , further including a visual output device coupled to the processing module and configured to generate a representation of the target object superimposed with the spectral signals correlated with their respective corresponding regions.
32. A method for detecting light signals relating to a vibratory target object, including the steps of:
receiving a light signal from each of a plurality of regions of the target object at a corresponding plurality of light amplitude modulation detectors;
generating from each received signal a signal that is correlated to a vibration of the corresponding region of the target object;
digitizing each correlated signal;
generating from the digitized signals an output representing the vibrations of the regions of the target object.
33. The method of claim 32 , further including the step of executing a Fourier transform on the digitized signals.
34. The method of claim 32 , wherein the plurality of detectors are arranged in a rectangular array.
35. The method of claim 32 , wherein the light signals include modulated light reflected from the target object.
36. The method of claim 35 , wherein the reflected light includes light having a frequency in at least one frequency range of visible, infrared and ultraviolet radiation.
37. The method of claim 32 , wherein the light signals include modulated light emitted from the target object.
38. The method of claim 37 , wherein the emitted light includes thermal infrared radiation.
39. The method of claim 37 , wherein the emitted light includes fluorescent radiation.
40. The method of claim 32 , further including the step of optically filtering the signals received from the plurality of regions.
41. The method of claim 32 , further including the step of generating contrast signals from the received signals relating to the vibrations of the corresponding regions.
42. The method of claim 32 , further including the step of displaying a representation of the target object visually correlated with the generated signals representing the vibrations of the corresponding regions.
43. The method of claim 32 , wherein the generating step includes the step of generating a temporal spectral signal corresponding to the vibration of each corresponding region.
44. The method of claim 32 , further including the step of extracting from the received signals a representation of an oscillation of the corresponding regions.
45. The method of claim 32 , wherein the extracting step includes the step of AC-coupling the received signals.
46. The method of claim 45 , wherein the extracting step includes the step of removing from the received signals at least one component representing ambient radiation in a vicinity of the target object.
47. A system for acoustically imaging a target object undergoing vibration, including:
an array of photodetectors;
a lens positioned to focus light signals received from individual regions of the target object onto the photodetectors, the light signals being modulated in a manner corresponding to vibrations of the individual regions;
a circuit coupled to each photodetector configured to isolate vibration signals from the light signals;
digitizing logic configured to digitize the vibration signals;
transform logic configured to extract frequency information from the digitized vibration signals; and
imaging logic configured to correlate the extracted frequency information with the corresponding regions of the target object, the correlated frequency information representing an light image of the target region.