Tunable interference contrast using a variable Wollaston prism

Abstract

A Fourier transform spectrometer (FTS) acquires interferogram data for spectral measurements. Conventional FTS instruments incorpo- rate Michelson interferometers. However, limitations of the Michelson for imaging applications have produced interest in alternative interferometer configurations. Common path interferometers, such as birefringent inter- ferometers, offer advantages for remote sensing applications. To ensure the best possible signal-to-noise ratio, the fringe contrast provided by the interferometer should be maximized. Unfortunately some birefringent interferometers, such as those that utilize Wollaston prisms (WPs), require stringent tolerances in order to ensure high fringe contrast across even a modest field of view (FOV). Fabricating an interferometer to meet these tolerances adds fabrication cost and time to the development of an instru- ment. We present how the introduction of additional birefringent elements into birefringent interferometer can be used to compensate for a decrease in fringe visibility due to manufacturing errors. These components form a variable angle WP (VWP), which can be used to vary the fringe visibility across the FOV. Experimental results confirming the ability of the VWP to vary the fringe visibility of a birefringent interferometer are included. These results are compared to polarization raytrace simulations for the system. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: