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.

We claim:  
     
         1 . A spectroscope comprising: 
 a catheter;    an optical fiber extending through the catheter, the optical fiber having a field-of-view; and    an obstruction disposed to occlude a portion of the field-of-view.    
     
     
         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 . A spectroscope comprising: 
 a catheter;    an optical fiber extending through the catheter;    an optical system in optical communication with the fiber, the optical system having a finite focal length.    
     
     
         14 . The spectroscope of  claim 13 , wherein the optical system comprises an optical element having a curved surface.  
     
     
         15 . The spectroscope of  claim 13 , wherein the optical system comprises an optical element having a spatially varying dielectric constant.  
     
     
         16 . The spectroscope of  claim 14 , wherein the curved surface comprises a cylindrical surface.  
     
     
         17 . The spectroscope of  claim 14 , wherein the curved surface includes a portion having a shape selected from the group consisting of a paraboloid, an ellipsoid, a hyperboloid, and a sphere.  
     
     
         18 . The spectroscope of  claim 13 , wherein the optical system comprises a mirror having a curved surface.  
     
     
         19 . The spectroscope of  claim 13 , wherein the optical system comprises a lens.  
     
     
         20 . A spectroscope comprising: 
 a catheter;    an optical fiber extending through the catheter;    a diffracting element in optical communication with the fiber, the diffracting element being configured to form a selected field-of-view.    
     
     
         21 . The spectroscope of  claim 20 , wherein the diffracting element comprises a transmissive diffracting element.  
     
     
         22 . The spectroscope of  claim 20 , wherein the diffracting element comprises a reflective diffracting element.  
     
     
         23 . The spectroscope of  claim 20 , wherein the diffracting element comprises a diffraction grating.  
     
     
         24 . The spectroscope of  claim 20 , wherein the diffracting element comprises an amplitude grating.  
     
     
         25 . The spectroscope of  claim 20 , wherein the diffracting element comprises a phase grating.  
     
     
         26 . The spectroscope of  claim 20 , wherein the diffracting element comprises a holographic grating.