Polarization Imaging with a waveplate array of femtosecond laser written nanogratings inside silica glass

Nanograting formation inside silica glass by femtosecond (fs) laser writing has attracted much attention [1], because micro birefringent optics can be fabricated by local generation of nanogratings [2,3]. One application of the micro birefringent optics is a waveplate array for polarization imaging [3]. In a polarization imaging camera, the incident light is detected by an imaging sensor after passing through a waveplate array and polarizer (Fig. 1 (a)). Because four intensities through waveplates of different slow axis are detected by four adjacent detectors in the imaging sensor (Fig. 1 (b)), polarization state can be analyzed only by a single acquisition of the light intensity distribution.