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US 7,623,285 B2Granted
Method and device for opto-acoustical imagery
AssigneeCentre National De La Recherche Scientifique
InventorMichel Jean Cross
Life of this patent
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Abstract
The inventive method for opto-acoustical imagery of an image object consists in a) generating an incident optical wave and a reference optical wave coherent therewith, b) oscillating the image object area at an acoustic frequency, c) sending the incident wave to said image object, thereby generating a diffused signal wave, d) sending at least one part of said diffused signal wave to a detection device, e) sending the reference optical wave to the detection device avoiding the image object, thereby generating an interferogram I (r, t), f) extracting digital information from said interferogram I (r, t), and in g) obtaining co-ordinates from one measurement point of the image object associated to said digital information.
Claims29
A method of acousto-optical imaging of an object to be imaged comprising the steps:
- (a) generating an incident optical wave, of frequency fI, and a reference optical wave, of frequency fR, this reference wave being coherent with the incident wave, and exhibiting therewith a known phase difference φi(t),
- (b) vibrating in a first object direction and at an acoustic frequency fA, a zone of the object to be imaged with the aid of a vibration generating device, and generating an acoustic wave, focused at a focal point situated in the object to be imaged,
- (c) applying said incident wave to the object to be imaged, and thus generating a scattered signal wave,
- (d) applying at least a part of the scattered signal wave to a detection device,
- (e) applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at the point r of the detection device an interferogram I(r, t) varying over time t,
- (f) extracting a digital information item from the interferogram I(r, t),
- (g) obtaining the coordinates of the focal point of the object to be imaged, to which the digital information item relates, and
- (e) repeating steps (a) to (g) for various focal points of the acoustic wave in the object to be imaged, these various focal points being aligned along the first object direction.
5 more elements
A method of acousto-optical imaging of an object to be imaged comprising the steps:
- (a) generating an incident optical wave, of freguency fI, and a reference optical wave, of frequency fR, this reference wave being coherent with the incident wave, and exhibiting therewith a known phase difference φi(t),
- (b) vibrating in a first object direction and at acoustic frequency fA, a zone of the object to be imaged with the aid of a vibration generating device,
- (c) applying said incident wave to the object to be imaged, and thus generating a scattered signal wave,
- (d) applying at least a part of the scattered signal wave to a detection device,
- (e) applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at the point r of the detection device an interferogram I(r, t) varying over time t,
- (f) extracting a digital information item from the interferogram I(r, t), and
- (g) obtaining the coordinates of a point of measurement of the object to be imaged, to which the digital information item relates,
- in which, in the course of a first iteration, steps (a) to (f) are performed for a first frequency fA of the acoustic wave and a first frequency fR of the reference wave, in the course of at least a second iteration, steps (a) to (f) are repeated for a second frequency f′A of the acoustic wave and a second frequency f′R of the reference wave, these second frequencies being coded respectively with the first frequencies, the method furthermore comprising a step in the course of which:
- (f′) at least one digital information item is obtained by decoding said digital information items obtained in the course of steps (f) of each iteration as a function of the frequencies used, and
- in which, in the course of step (g), the coordinates of at least one point of measurement of the object to be imaged to which the digital information item obtained in the course of step (f′) relates are obtained, by decoding the said digital information items obtained in the course of steps (f) of each iteration as a function of the frequencies used.
7 more elements
A method of acousto-optical imaging of an object to be imaged comprising the steps:
- (a) generating an incident optical wave, of frequency fI, and a reference optical wave, of frequency fR, this reference wave being coherent with the incident wave, and exhibiting therewith a known phase difference φi(t),
- (b) vibrating in a first object direction and at an acoustic frequency fA, a zone of the object to be imaged with the aid of a vibration generating device,
- (c) applying said incident wave to the object to be imaged, and thus generating a scattered signal wave,
- (d) applying at least a part of the scattered signal wave to a detection device,
- (e) applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at the point r of the detection device an interferogram I(r, t) varying over time t,
- (f) extracting a digital information item from the interferogram I(r, t), and estimating the complex amplitude Es(r) of the acoustic component on the basis of the interferogram I(r,t), and
- (g) obtaining the coordinates of a point of measurement of the object to be imaged, to which the digital information item relates.
4 more elements
A method of acousto-optical imaging of an object to be imaged comprising the steps:
- (a) generating an incident optical wave, of frequency fI, and a reference optical wave, of frequency fR, this reference wave being coherent with the incident wave and exhibiting therewith a known phase difference φi(t),
- (b) vibrating in a first object direction and at an acoustic frequency fA, a zone of the object to be imaged with the aid of a vibration generating device,
- (c) applying said incident wave to the object to be imaged, and thus generating a scattered signal wave,
- (d) applying at least a part of the scattered signal wave to a detection device,
- (e) applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at the point r of the detection device an interferogram I(r, t) varying over time t,
- (f) extracting a digital information item from the interferogram I(r, t), and
- (g) obtaining the coordinates of a point of measurement of the object to be imaged, to which the digital information item relates,
- wherein in the course of step (a),
- a laser source of wavelength λ emits an emission wave, of frequency fL,
- amplitude modulation means of the emission wave, generate a carrier wave of incident frequency fI, and at least one amplitude modulation lateral band, which corresponds to a wave of frequency fR,
- a semireflecting mirror, transmits a part of the lateral band wave and a part of the carrier wave forming the incident wave, and reflects a part of the carrier wave and a part of the lateral band wave forming the reference wave.
8 more elements
A method of acousto-optical imaging of an object to be imaged comprising the steps:
- (a) generating an incident optical wave, of frequency fI, and a reference optical wave, of frequency fR, this reference wave being coherent with the incident wave, and exhibiting therewith a known phase difference φi(t),
- (b) vibrating in a first object direction and at an acoustic frequency fA, a zone of the object to be imaged with the aid of a vibration generating device,
- (c) applying said incident wave to the object to be imaged, and thus generating a scattered signal wave,
- (d) applying at least a part of the scattered signal wave to a detection device,
- (e) applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at the point r of the detection device an interferogram I(r, t) varying over time t,
- (f) extracting a digital information item from the interferogram I(r, t), and
- (g) obtaining the coordinates of a point of measurement of the object to be imaged, to which the digital information item relates,
- wherein in the course of step (a),
- a laser source of wavelength λ emits an emission wave, of frequency fL,
- a first acousto-optical modulator transmits a part of the emission wave to form the incident wave on the object to be imaged, and moreover generates a first frequency shifted wave, the frequency of which is shifted by a value δf1, possibly negative, with respect to the emission wave, and
- a second acousto-optical modulator intercepts the first frequency shifted wave and generates a second frequency shifted wave, the frequency of which is shifted by a value δf2, possibly negative, with respect to the shifted wave, the second frequency shifted wave forming the reference wave, the frequency of which is thus shifted in frequency with respect to the incident wave by a value δf=δf1+δf2, thus determining a known phase difference φi(t) between these two waves.
8 more elements
A method of acousto-optical imaging of an object to be imaged comprising the steps:
- (a) generating an incident optical wave, of frequency fI, and a reference optical wave, of frequency fR, this reference wave being coherent with the incident wave, and exhibiting therewith a known phase difference φi(t),
- (b) vibrating in a first object direction and at an acoustic frequency fA, a zone of the object to be imaged with the aid of a vibration generating device,
- (c) applying said incident wave to the object to be imaged, and thus generating a scattered signal wave,
- (d) applying at least a part of the scattered signal wave to a detection device,
- (e) applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at the point r of the detection device an interferogram I(r, t) varying over time t,
- (f) extracting a digital information item from the interferogram I(r, t), and
- (g) obtaining the coordinates of a point of measurement of the object to be imaged, to which the digital information item relates,
- wherein in the course of step (a), two independent laser sources, locked in phase by electronic slaving, generate the incident and reference waves, exhibiting a known phase difference φi(t) between them.
5 more elements
A method of acousto-optical imaging of an object to be imaged comprising the steps:
- (a) generating an incident optical wave, of frequency fI, and a reference optical wave, of frequency fR, this reference wave being coherent with the incident wave, and exhibiting therewith a known phase difference φi(t),
- (b) vibrating in a first object direction and at an acoustic frequency fA, a zone of the object to be imaged with the aid of a vibration generating device,
- (c) applying said incident wave to the object to be imaged, and thus generating a scattered signal wave,
- (d) applying at least a part of the scattered signal wave to a detection device,
- (e) applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at the point r of the detection device an interferogram I(r, t) varying over time t,
- (f) extracting a digital information item from the interferogram I(r, t), and
- (g) obtaining the coordinates of a point of measurement of the object to be imaged, to which the digital information item relates,
- wherein in the course of step (a),
- a laser source of wavelength λ emits an emission wave, of frequency fL,
- a semireflecting mirror transmits a part of the emission wave to form the incident wave on the object to be imaged, and transmits a second part of the emission wave,
- a first acousto-optical modulator intercepts the second part of the emission wave and generates a first frequency shifted wave, with frequency shifted by a value δf1, possibly negative, with respect to the emission wave, and
- a second acousto-optical modulator intercepts the first frequency shifted wave and generates a second frequency shifted wave, the frequency of which is shifted by a value δf2, possibly negative, with respect to the shifted wave, the second frequency shifted wave forming the reference wave, the frequency of which is thus shifted in frequency with respect to the incident wave by a value δf=δf1=δf2, thus determining a known phase difference φi(t) between these two waves.
9 more elements
A method of acousto-optical imaging of an object to be imaged comprising the steps:
- (a) generating an incident optical wave, of frequency fI, and a reference optical wave, of frequency fR, this reference wave being coherent with the incident wave, and exhibiting therewith a known phase difference φi(t),
- (b) vibrating in a first object direction and at an acoustic frequency fA, a zone of the object to be imaged with the aid of a vibration generating device,
- (c) applying said incident wave to the object to be imaged, and thus generating a scattered signal wave,
- (d) applying at least a part of the scattered signal wave to a detection device,
- (e) applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at the point r of the detection device an interferogram I(r, t) varying over time t,
- (f) extracting a digital information item from the interferogram I(r, t), and
- (g) obtaining the coordinates of a point of measurement of the object to be imaged, to which the digital information item relates,
- wherein the vibration generating device is used to obtain an acoustic cue of the zone of the object to be imaged, and in which the digital information item extracted in step (f) is used jointly with said acoustic cue.
5 more elements
An installation for acousto-optical imaging of an object to be imaged comprising:
- means for generating an incident optical wave, of frequency fI, and a reference optical wave of frequency fR, this reference wave being coherent with the incident wave and exhibiting therewith a known phase difference φi(t),
- a vibration generating device for vibrating in a first object direction and at an acoustic frequency fA a zone of the object to be imaged,
- means for applying the said incident wave to the object to be imaged, thus generating a scattered signal wave,
- a detection device,
- means for applying at least part of this scattered signal wave to the detection device,
- means for applying the reference wave to the detection device without making it pass through the object to be imaged, thereby generating at point r of the detection device an interferogram I(r, t) varying over time t, and
- means for extracting a digital information item, estimating the complex amplitude Es(r) of the acoustic component on the basis of the interferogram I(r,t), and obtaining the coordinates of a point of measurement of the object to be imaged, to which the digital information item relates, from the interferogram.
4 more elements
Dependencies are inferred from the claim text.