Optical arrangement for analysis of refractive index

Claim 1

AN OPTICAL APPARATUS FOR THE ANALYSIS OF VARIATIONS IN REFRACTIVE INDEX OF A SOLUTION IN A CELL WHERE THE REFRACTIVE INDEX GRADIENT HAS EVERYWHERE THE SAME DIRECTION, SAID APPARATUS GIVING COMBINED RECORDS OF THE REFRACTIVE INDEX AND ITS DERIVATIVE WITH RESPECT TO THE POSITION ALONG THE DIRECTION OF SAID REFRACTIVE INDEX GRADIENT, COMPRISING AN ILLUMINATION DEVICE FOR THE PRODUCTION OF MONOCHROMATIC RADIATION, A SLIT ARRANGEMENT HAVING AT LEAST ONE NARROW SLIT ILLUMINATED BY SAID DEVICE, A LENS SYSTEM GIVING AN OPTICAL IMAGE OF SAID SLIT, A CELL FOR THE SOLUTION TO BE MEASURED PLACED IN RELATION TO SAID LENS SYSTEM SO AS TO BE COMPLETELY AND EVENLY ILLUMINATED, A BEAM-SPLITTING DEVICE FOR THE PRODUCTION OF TWO COHEREN BEAMS OF LIGHT OF EQUAL DIMENSIONS AND INTENSITIES, ONE OF THEM BEING DIRECTED THROUGH THE CELL AND THE OTHER BESIDE THE CELL THROUGH A MEDIUM OF CONSTANT REFRACTIVE INDEX, THE OPTICAL PATHS OF THE TWO BEAMS OF LIGHT BEING ESSENTIALLY OF THE SAME LENGHT, A BEAM-COLLECTING DEVICE FOR REUNION OF THE TWO BEAMS OF LIGHT, A PARTLY LIGHTOBSTRUCTING DEVICE SITUATED IN THE FIRST IMAGE PLANE OF THE LIGHT SOURCE SLIT AND HAVING AT LEAST ONE RECTILINEAR EDGE, A LENS SYSTEM GIVING AN OPTICAL IMAGE OF THE CELL AT LEAST IN THE SECTION PARALLEL WITH THE OPTICAL PROJECTION OF THE REFRACTIVE INDEX GRADIENT, A DEVICE FOR HOLDING A PHOTOGRAPHIC FILM OR PLATE IN THE PLANE OF SAID OPTICAL IMAGE, AND A DEVICE FOR TRANSFORMING THE LIGHT DEFLECTION AT SAID LIGHT-OBSTRUCTING DEVICE, SAID DEFLECTION GOING IN THE DIRECTION OF SAID GRADIENT PROJECTION, INTO A LIGHT DEFLECTION PERPENDICULAR THERETO IN THE IMAGE PLANE OF THE CELL.