Probe apparatus for measuring depth-limited properties with low-coherence enhanced backscattering

Abstract

Low-coherence enhanced backscattering (LEBS) spectroscopy is an angular resolved backscattering technique that is sensitive to sub-diffusion light transport length scales in which information about the scattering phase function is preserved. Lens-based and lens-free fiber optic LEBS probes are described that are capable of measuring optical properties of a target tissue through depth-limited measurements of backscattering angles within the enhanced backscattered cone.

What is claimed is: 
     
         1 . A method for performing depth-limited measurement of optical properties of a target tissue through low-coherence enhanced backscattering spectroscopy comprising:
 illuminating the target tissue with broadband light from a distal end of an illumination fiber, wherein the optical path of broadband light from the illumination fiber to the target tissue passes through an optical component;   detecting backscattered light at a plurality of backscattering angles with a plurality of detection fibers, wherein a first detection fiber detects an incoherent baseline of backscattered light, and at least a second detection fiber detecting backscattering angles within the enhanced backscattered cone.   
     
     
         2 . The method of  claim 1 , wherein the optical component is an optical spacer housed, in whole or in part, in a tip assembly of an optical probe, and the penetration depth of the broadband light in the target tissue is determined by the length of the optical spacer. 
     
     
         3 . The method of  claim 2 , wherein a part of the optical spacer is housed in a trunk assembly, and another part of the optical spacer is housed in a tip assembly configured to be releasably connected to the trunk assembly. 
     
     
         4 . The method of  claim 3 , wherein the optical spacer comprises a transparent cover slide, and a distance between the cover slide and distal end of the illumination fiber comprises air and/or a transparent material with a selected index of refraction value, and defines a spatial coherence length of the probe. 
     
     
         5 . The probe of  claim 2 , wherein the optical spacer further comprises a mask disposed at a distance from the distal end of the illumination fiber. 
     
     
         6 . The probe of  claim 5 , wherein the optical path is further defined as traveling along a first axis, wherein the mask comprises an annular surface disposed at an angle of between 40 and 70 degrees relative to the first axis terminating in an opening. 
     
     
         7 . A low-coherence enhanced backscattering probe comprising:
 a fiber optic array comprising an illumination fiber adapted to illuminate a target tissue with broadband light from a distal end, a first detection fiber for detecting an incoherent baseline of backscattered light, and at least a second detection fiber for detecting backscattering angles within the enhanced backscattered cone.   
     
     
         8 . The probe of  claim 7 , further comprising a tip assembly including an optical component, wherein the optical path of broadband light from the illumination fiber to the target tissue passes through the optical component. 
     
     
         9 . The probe of  claim 8 , wherein the optical component is an optical spacer housed, in whole or in part, in a tip assembly of an optical probe, and the penetration depth of the broadband light in the target tissue is determined by the length of the optical spacer. 
     
     
         10 . The probe of  claim 9 , wherein a part of the optical spacer is housed in a trunk assembly, and another part of the optical spacer is housed in the tip assembly configured to be releasably connected to the trunk assembly. 
     
     
         11 . The probe of  claim 10 , wherein the optical spacer comprises a transparent cover slide, and a distance between the cover slide and distal end of the illumination fiber comprises air and/or a transparent material with a selected index of refraction value, and defines a spatial coherence length of the probe. 
     
     
         12 . The probe of  claim 8 , wherein the optical spacer further comprises a mask disposed at a distance from the distal end of the illumination fiber. 
     
     
         13 . The probe of  claim 12 , wherein the optical path is further defined as traveling along a first axis, wherein the mask comprises an annular surface disposed at an angle of between 40 and 70 degrees relative to the first axis terminating in an opening.