POLARIMETER FOR APPLICATION TO THE NON-DESTRUCTIVE EVALUATION (NDE) OF MATERIALS

THIS PROPOSAL DESCRIBES THE DESIGN AND FABRICATION OF A NEW TYPE OF POLARIMETER WHICH WE CALL A SINGLE APERTURE-FOUR CHANNEL OPTICAL POLARIMETER. IT IS DESIGNED TO MEASURE SIMULTANEOUSLY THE FOUR STOKES POLARIZATION PARAMETERS OF AN OPTICAL BEAM AND IS CAPABLE OF MEASURING THE STOKES PARAMETERS OF EITHER A CW OR PULSED OPTICAL BEAM. THE POLARIMETER IS READILY ADAPTED TO ELLIPSOMETRY AND IT IS TO THIS FIELD THAT WE APPLY THE POLARIMETER. WE SHOW THAT IF AN OPTICAL SURFACE (E.G., A DIELECTRIC FILM) IS ILLUMINATED WITH A SINGLE PULSE OF RIGHT OR LEFT CIRCULARLY POLARIZED LIGHT THEN THE ELLIPSOMETRIC PARAMETERS AND, CONSEQUENTLY, THE INDEX OF REFRACTION AND THE THICKNESS OF THE THIN-FILM CAN BE FOUND. THE TECHNICAL PORTION OF THE PROPOSED FIRST DISCUSSES THE CONCEPTUAL FOUNDATIONS FOR THE OPTICAL POLARIMETER FOR IT TO OPERATE AS AN ELLIPSOMETER. THIS IS FOLLOWED BY A DISCUSSION OF THE PROPOSED DESIGN AND ITS OPERATION. IN A FINAL SECTION WE PRESENT A DESCRIPTION OF THE REQUIRED SIGNAL PROCESSING OF THE FOUR CHANNELS.