Abstract
Arrangements are disclosed for producing images based upon diffusional wave theory and frequency domain analysis. A medium to be imaged is illuminated with amplitude modulated radiation, and diffusional radiation transmitted or reflected by the medium is detected at a plurality of detection locations, as by a television camera. The phase and also the amplitude demodulation of the amplitude modulated diffusional radiation is detected at each detection location. A relative phase image and also a demodulation amplitude image of the medium are then generated from respectively the detected relative phase values and the detected demodulation amplitudes of the diffusional radiation at the plurality of locations. The present invention is particularly suited for medical applications for generating images of internal anatomical details of the body by using a near infrared amplitude modulated source for illumination of the body. In such medical applications, the body is illuminated with near infrared radiation having a wavelength between 600 and 1200 nanometers which is amplitude modulated at a frequency in the megahertz to gegihertz range, and internal images of the patient are generated for medical diagnosis. In preferred embodiments, a laser is utilized to generate the near infrared radiation near or below a 10 watt power level which is coupled by fiber optic cables to the body of the patient. Detection is also with fiber optic cables placed in direct contact with an opposed surface of the body which couple the transmitted diffusional radiation to an image intensifier placed in front of a television camera detector. The gain of the image intensifier is modulated at a frequency to obtain a heterodyned output frequency of less than 60 hertz which is within the detection bandwidth of the television camera.
| Original language | English (US) |
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| U.S. patent number | 5213105 |
| Filing date | 12/4/90 |
| State | Published - May 25 1993 |