Acousto-optic monitoring and imaging in a depth sensitive manner

Abstract

A system monitors or images a portion of a sample. The system includes an optical interferometer with a measurement arm, a reference arm, and an optical splitter. The arms are coupled to receive light from the optical splitter. One of the arms includes an acousto-optical modulator. The interferometer is configured to interfere light output from the two arms. The system also includes a detector that receives the interfered light and uses the received light to determine a depth-dependent quantity characterizing a portion of the interior of the sample.

What is claimed is:  
     
         1 . A system for monitoring or imaging a sample, comprising: 
 an optical interferometer comprising a measurement arm, a reference arm, and an optical splitter, the arms being coupled to receive light from the optical splitter, the interferometer being configured to interfere light outputted by the arms, one of the arms having an acousto-optical modulator; and    a detector configured to receive the interfered light and to use the received light to determine a depth-dependent quantity characterizing a portion of the interior of the sample.    
     
     
         2 . The system of  claim 1 , wherein the quantity is representative of one of a signed displacement and a velocity of the portion of the interior of the sample  
     
     
         3 . The system of  claim 1 , wherein the quantity is representative of a signed displacement of the portion of the interior of the sample.  
     
     
         4 . The system of  claim 2 , further comprising: 
 an optical source coupled to transmit light to the measurement and reference arms and capable of producing light with a coherence length of less than 1 centimeter.    
     
     
         5 . The system of  claim 2 , further comprising: 
 an optical source coupled to transmit light to the measurement and reference arms and capable of producing light with a coherence length of less than 1 millimeter.    
     
     
         6 . The system of  claim 2 , where in one of the reference arm and the measurement arm has a variable optical path length.  
     
     
         7 . A system for medical monitoring or imaging of a patient or animal, comprising: 
 an optical interferometer having a measurement arm, a reference arm, and an optical splitter, the arms being coupled to receive light from the optical splitter and configured to cause light outputted by the arms to interfere; and    an interference detector coupled to receive a portion of the interfering light and configured to determine information representative of a location, an orientation, or a velocity of a portion of the patient or animal from the received light; and    a controller coupled to receive the information and to adjust collected data on the animal or patient in a manner responsive to a change in a relative location, orientation, or velocity between a probe and a portion of the interior of a tissue in the animal or patient.    
     
     
         8 . The system of  claim 7 , wherein the controller is configured to adjust collected image data to correct the image data for motion of the interior of the tissue in the animal or patient.  
     
     
         9 . The system of  claim 7 , wherein the controller is configured to control the position of the probe.  
     
     
         10 . The system of  claim 7 , wherein one of the reference arm and the measurement arm has a variable optical path length.  
     
     
         11 . The system of  claim 7 , wherein one of the reference arm and the measurement arm includes an acousto-optical modulator.  
     
     
         12 . The system of  claim 7 , wherein the detector is configured to determine one of a velocity and a signed displacement of the portion of the interior of the tissue based on the received interfering light.  
     
     
         13 . The system of  claim 7 , wherein the measurement arm includes an optical endoscope for sending light to and receiving light from the portion of the interior of the tissue of the patient or animal.  
     
     
         14 . The system of  claim 13 , wherein the endoscope includes an optical fiber configured to perform the sending and receiving.  
     
     
         15 . A process for monitoring a sample, comprising: 
 transmitting light to measurement and reference arms of an interferometer;    acousto-optically frequency shifting light in one of the reference arm and the measurement arm;    collecting light from the measurement arm in response to the light scattering off a portion of the interior of the sample; and    interfering light from the reference arm with the collected light.    
     
     
         16 . The process of  claim 15 , further comprising: 
 determining one of a velocity and a signed displacement of the portion of the interior of the sample based on a measurement of the interfering light.    
     
     
         17 . The process of  claim 15 , wherein the transmitted light has a coherence length of less than 1 centimeter.