Endoscope with a smoothly curved distal end face

Claim 1

An endoscope of the direct-viewing type comprising: a rigid elongated outer sheath having a distal end to be inserted into a body cavity, said distal end having a distal end face; an observation system longitudinally disposed inside said sheath for essentially the entire length of said sheath and having one end portion connected to a view window located in the distal end of said outer sheath, said view window having a smooth outer glass face disposed along the longitudinal centerline of said sheath in the center of the distal end face; a plurality of light conducting optical fibers longitudinally arranged inside said outer sheath, said fibers having distal ends concentrically surrounding said view window, said fiber distal ends forming a portion of said distal end face and being ground to form an annular convexedly spherical distal end portion which forms a single continuous surface with said view window, said fiber distal ends being ground so that said annular convexedly spherical distal end portion is shaped to have a curvature which directs light from said fiber distal ends towards said view window so that light directed through some of said fibers overlaps light directed through others of said fibers to illuminate the region of the body cavity observed through said view window.