Method and apparatus for localization and spectroscopy of objects using optical frequency modulation of diffusion waves
First Claim
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1. A method for determining an optical property of an object located in a turbid medium comprising the steps of:
- generating a beam of amplitude modulated electromagnetic radiation which alternates between different colors at a predetermined modulation rate;
choosing said different colors such that said different colors interact with said object differently while interaction between said different colors and said turbid medium is substantially the same;
applying said beam to said medium to generate diffuse photon density waves within said medium such that said diffuse photon density waves interact with said object;
detecting output from said medium and storing a differential signal resulting from said modulation at said predetermined modulation rate; and
deriving information about said optical property of said object from said differential signal.
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Abstract
An apparatus and method for using frequency modulated diffusive photon-density waves propagating through a turbid medium such as tissue for detecting optical properties of objects and for imaging objects within the turbid medium. Frequency modulation enables real time differential measurement of the interaction of different colors with the object when the different colors are chosen such that they react the same with the medium but differently with the object. The method greatly simplifies optical imaging and increases the amount of information which may be obtained about the object.
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21 Claims
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1. A method for determining an optical property of an object located in a turbid medium comprising the steps of:
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generating a beam of amplitude modulated electromagnetic radiation which alternates between different colors at a predetermined modulation rate; choosing said different colors such that said different colors interact with said object differently while interaction between said different colors and said turbid medium is substantially the same; applying said beam to said medium to generate diffuse photon density waves within said medium such that said diffuse photon density waves interact with said object; detecting output from said medium and storing a differential signal resulting from said modulation at said predetermined modulation rate; and deriving information about said optical property of said object from said differential signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for determining an optical property of an object located in a turbid medium comprising:
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a source of amplitude modulated electromagnetic radiation which alternates between different colors at a predetermined modulation rate, said different colors selected such that said object interacts with said different colors differently and said medium interacts with said different colors substantially the same; means for applying said beam to said medium to generate diffuse photon density waves within said medium such that said diffuse photon density waves interact with said object; means for receiving the output from said medium and storing a differential signal resulting from said modulation at said predetermined modulation rate; and means for deriving information about said optical property of said object from said differential signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for determining an optical property of an object located in a-turbid medium comprising the steps of:
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generating a beam of amplitude modulated electromagnetic radiation which is frequency modulated to alternate between different colors at a predetermined modulation frequency; choosing said different colors such that said different colors interact with said object differently while interaction between said different colors and said turbid medium is substantially the same; applying said beam to said medium to generate diffuse photon density waves within said medium such that said diffuse photon density waves interact with said object; detecting output from said medium and generating a signal corresponding to said output; processing said signal such that phase and amplitude information arising from modulations in photon density from both said amplitude modulation frequency and said frequency modulation frequency is retained; and deriving information about a location of said object and said optical property of said object by analyzing a spatial pattern and color variation in said phase and amplitude information. - View Dependent Claims (20)
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21. An apparatus for determining a property of an object located in a medium, comprising:
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a source of amplitude modulated electromagnetic radiation which is frequency modulated between different frequencies at a predetermined modulation rate, said different frequencies being selected such that said object interacts with said different frequencies differently and said medium interacts with said different frequencies substantially the same, said source of electromagnetic radiation being incident upon said medium; a detector located to detect at least a portion of said electromagnetic radiation after said portion has interacted with said object and said medium, said detector producing an output signal representative of said detected electromagnetic radiation; and a processor coupled to receive said output signal, said processor determining said property of said object from said output signal.
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Specification