DIFFERENTIAL POLARIZATION INTERFEROMETER

摘要

A differential polarization interferometer is provided. An interferometer performs direct measurement of phase shift of a light wave passed under an arbitrary angle through a sample composed of a transparent substrate holding a thin deposited test film, for metamaterial testing. An example apparatus has a laser source and a first polarizer, and two optically connected arms. A first arm creates orthogonally polarized components of a single output beam for a broadband non-polarizing beam splitter. A second arm has a controllable phase retarder to introduce a phase shift into one polarization component of the reflected single output beam, and a second polarizer to equalize and mix the polarization components of the reflected single output beam. This transforms the reflected single output beam into a beam resulting from interference of polarization components of the reflected single output beam. A photodetector transforms an intensity of the beam into an electric signal for output.

主权项

1. A differential polarization interferometer, comprising:
a tunable laser source of coherent radiation generating an input beam; a first polarizer which allows to convert the input beam into a polarized beam with adjustable intensities of orthogonally polarized components; a broadband non-polarizing beam splitter forming two optically connected arms, a first one with a transmitted polarized beam; in a first branch formed with the transmitted polarized beam there are sequentially arranged:
a birefringent element configured to split the transmitted polarized beam into two separate, parallel, orthogonally polarized, a reference beam and an object beam, and mounted on a base with fine rotation; anda sample consisting of a transparent substrate, on the part of which a film under test is deposited, and mounted on the base with adjustable shift and rotation; anda chopper wheel with a system of holes that opens sequentially for some time the object beam and the reference beam separately, then simultaneously, providing interference of the object beam and the reference beam; anda broadband plane mirror reflecting an incident reference beam and an incident object beam in the opposite direction and providing double passing of the reference beam and the object beam through the sample and the birefringent element which converts the reference beam and the object beam into orthogonally polarized components of a single output beam falling on the broadband non-polarizing beam splitter; in a second arm of the interferometer formed with a reflected single output beam there are sequentially arranged:
a controllable phase retarder configured to introduce phase shift only into one polarization component of the reflected single output beam; anda second polarizer that equalizes and mixes the polarization components of the reflected single output beam and transforms the reflected single output beam into a beam which is the result of interference of polarization components of the reflected single output beam; and a photodetector configured to receive the beam as input and transform an intensity of the beam into an output electric signal which can be amplified and analyzed by various electronic devices.