Interference microscope optical systems

Claim 1

AN INTERFERENCE MICROSCOPE COMPRISING IN COMBINATION A CONDENSER, SPECIMEN STAGE AND OBJECTIVE IN OPTICAL ALIGNMENT, SAID CONDENSER AND OBJECTIVE EACH HAVING OPTICALLY ALIGNED THEREWITH A BIREFRINGENT ELEMENT AND WITH SAID BIREFRINGENT ELEMENTS BEING DISPOSED AT OPPOSITE SIDES OF SAID STAGE, THE FIRST OF WHICH IS ADAPTED TO LINEARLY POLARIZE AND SEPARATE LIGHT INCIDENT ON SAID CONDENSER INTO TWO COHERENT ORTHOGONALLY POLARIXED ADJACENTLY SPACED BEAMS, BOTH OF SAID BEAMS BEING ADAPTED TO PASS THROUGH SAID SPECIMEN STAGE AND THE OTHER OF WHICH BIREFRINGENT ELEMENTS IS ADAPTED TO RE-COMBINE SAID COHERENT ORTHOGONALLY POLARIZED ADJACENT BEAMS FOR PASSAGE THROUGH SAID OBJECTIVE, SAID OBJECTIVE FUNCTIONING TO FOCUS SAID RE-COMBINED COHERENT ORTHOGONALLY POLARIZED BEAMS AT AN IMAGE PLANE, A ROTATABLE LINEAR POLARIZER IN OPTICAL ALIGNMENT WITH SAID CONDENSER AND BEING ADAPTED TO VARY THE RELATIVE AMPLITUDES OF SAID TWO COHERENT ORTHOGONALLY POLARIZED BEAMS, AND LIGHT PATH DIFFERENCE MEASURING MEANS IN OPTICAL ALIGNMENT WITH SAID OBJECTIVE FOR MEASURING THE RELATIVE PHASE DIFFERENCE BETWEEN SAID COMBINED COHERENT ORTHOGONALLY POLARIZED BEAMS.