Optical apparatus with sinusoidal mask for the observation of phase objects

Claim 1

IN APPARATUS FOR THE OBSERVATION OF PHASE OBJECTS BY INTERFERENTIAL CONTRAST, THE APPARATUS HAVING A LIGHT SOURCE COMPRISING AT LEAST ONE OPTICAL SLIT, A FIRST OBJECTIVE YIELDING AN IMAGE OF THE SOURCE, MEANS FOR HOLDING A PHASE OBJECT BEYOND THE FIRST OBJECTIVE, AND A MASK, THE FIRST OBJECTIVE YIELDING AN IMAGE OF THE LIGHT SOURCE LOCATED IN THE VICINITY OF THE MASK IN ALIGNMENT WITH A PHASE OBJECT MOUNTED ON THE HOLDER, AND A SECOND OBJECTIVE PRODUCING AN OBSERVABLE AND EXAMINABLE IMAGE OF THE PHASE OBJECT, THE LIGHT SOURCE, THE FIRST AND SECOND OBJECTIVES, AND THE PHASE OBJECT HOLDING MEANS, LYING GENERALLY ALONG THE OPTICAL AXIS OF THE APPARATUS, THE IMPROVED MASK WHICH COMPRISES A BODY HAVING A TRANSPARENT ZONE THERETHROUGH IN THE SHAPE OF ONE-HALF A SINUSOID, THE MASK BEING PLACED SO THAT THE OPTICAL AXIS OF THE APPARATUS INTERSECTS THE PERIODIC AXIS OF THE MASK AT A PREDETERMINED LOCATION OUT OF PHASE FROM THE ZONE OF MAXIMUM AMPLITUDE OF THE SINUSOID, THE AXIS OF SAID SLIT BEING SYMMETRICAL WITH, AND AT RIGHT ANGLES TO THE AXIS OF THE SINUSOID.