This paper presents the firsts steps of the development of a new spectropolarimeter with a high potential for space applications. The instrument, designed on birefringent elements, avoids the need for rotating elements and may cover the entire Stokes vector on a large wavelength band. In addition, the architecture of the modulator enables a very high polarimetric efficiency, placing this concept above classical spectropolarimeters. A new proof for the solution uniqueness is presented, and base on that, a thorough analysis of the polarimetric efficiency.

An innovative model of a static spectropolarimeter able to cover the entire Stokes vector is discussed. The optical layout is based on a birefringent modulator formed by two antiparallel prisms stuck together with the help of an intermediary part of the same material. This optical model has the advantage of being extremely compact. It avoids any movable parts or rotating components. By its architecture, the device induces a complete modulation on the vertical direction of any incoming polarized light, facilitating the determination of the entire Stokes vector through a single measurement. Because the modulation is also wavelength-dependent, spectral dependencies of the polarization states can be derived. The behavior of the model was first investigated in noise-free conditions. The existence of a unique solution was proven in the absence of noise and for any Stokes vector configuration. Under noisy conditions, the uncertainty on the Stokes parameters and the efficiency of the modulation scheme were evaluated as a function of the analyzer’s angle and for two different configurations of the modulator. The simulations show that an almost ideal efficiency is reachable, qualifying the concept for the high-precision measurement of the polarization.