Spectroscope With Modified Field-of-View

Abstract

A spectroscope for detecting vulnerable plaques includes an optical fiber extending through a catheter. The optical fiber has a field-of-view that is modified to preferentially collect light scattered from deep within the wall of a blood vessel. Obstructions or curved optical surfaces can be used to modify the field of view.

1 . A spectroscope comprising:
 a catheter;   an optical fiber having a core and extending through the catheter, the optical fiber having a field-of-view; and   an obstruction disposed within the field-of-view of said optical fiber to prevent light in a selected zone from illuminating the core.   
     
     
         2 . The spectroscope of  claim 1 , wherein the obstruction comprises a ledge extending across a chord of the core, the ledge occluding a region bounded by the chord and by a boundary of the core. 
     
     
         3 . The spectroscope of  claim 1 , wherein the obstruction comprises a tab extending at least part way across the core. 
     
     
         4 . The spectroscope of  claim 3 , wherein the tab comprises a curved tip. 
     
     
         5 . The spectroscope of  claim 1 , wherein the obstruction comprises a disk disposed to occlude a circular portion of the field-of-view. 
     
     
         6 . The spectroscope of  claim 1 , further comprising a mirror in optical communication with the optical fiber; and wherein the obstruction comprises a non-reflective region of the mirror, the non-reflective region being shaped to obstruct a portion of the field-of-view thereof. 
     
     
         7 . The spectroscope of  claim 1 , further comprising a perforated mask enclosing the fiber; and wherein the obstruction comprises walls forming an aperture in optical communication with the fiber, the aperture being shaped to obstruct a portion of the field-of-view thereof. 
     
     
         8 . The spectroscope of  claim 1 , further comprising a transparent sheath surrounding the fiber; and wherein the obstruction comprises an opaque band in optical communication with the fiber and positioned to obstruct a portion of the field-of-view thereof 
     
     
         9 . The spectroscope of  claim 1 , wherein the obstruction has a shape selected to form a field-of-view in the shape of a truncated ellipse. 
     
     
         10 . The spectroscope of  claim 1 , wherein the obstruction has a shape selected to form a field-of-view in the shape of a crescent. 
     
     
         11 . The spectroscope of  claim 1 , wherein the obstruction has a shape selected to form an annular field-of-view. 
     
     
         12 . The spectroscope of  claim 1 , wherein the obstruction has an edge configured to diffract light incident thereon to form a selected field-of-view. 
     
     
         13 - 26 . (canceled) 
     
     
         27 . The spectroscope of  claim 1 , wherein the optical fiber comprises the collection fiber. 
     
     
         28 . The spectroscope of  claim 1 , wherein the field of view includes a specular zone and a re-entrant zone. 
     
     
         29 . The spectroscope of  claim 28 , wherein the obstruction is disposed to prevent light in the specular zone from illuminating the core. 
     
     
         30 . The spectroscope of  claim 29 , wherein the obstruction is configured to prevent substantially all of the light in the specular zone from illuminating the core.