Apparatus for measuring the refractive index of liquids or gases

Claim 1

Apparatus for measuring the refractive index of fluids contained in a fluid retainer, comprising: a means forming radiation transmitting region; a means forming radiation receiving region; a source of radiation coupled to said radiation transmitting region; a radiation sensitive means coupled to said radiation receiving region; a light conductor having a surface generated by rotation of a curve having a progressively decreasing radius of curvature about an axis of rotation, whereby said surface merges into a substantially-rounded, vertex-tip, measuring, surface area without the radius of surface curvature becoming zero at said vertex-tip, measuring, surface area, said surface defining a single radiation input and output window at an intersection of said surface with a plane normal to said axis of rotation, said vertex-tip, measuring, surface area having the function of contacting said fluids in said retainer to have its light transmitting properties modified thereby; and said radiation transmitting region and said radiation receiving region being located on the opposite side of said window from said vertex-tip measuring-point surface area, and on substantially diametrically opposite sides of a center of said window, said radiation transmitting region radiating light through said window toward said vertex-tip measuring-point surface area and said radiation receiving region receiving light passing through said window from said vertex-tip measuring-point surface area, such that said radiation transmitting region and said radiation receiving region thereby being arranged that said radiation sensitive means receives predominantly light which is reflected from said vertex-tip measuring-point surface area.