New experimental set-up based on LC technology for simultaneously achieving super-resolved and polarimetric images

A. LIZANA; A. PEINADO; C. IEMMI; J. CAMPOS

Santiago de Compostela

Congreso; ICO 23; 2014

International Comission for Optics

The resolution of an imaging system is limited by many factors, as the aperture size of the elements in the system, the imaging wavelength, misalignments and imperfections of the optical components, among others. Because of high resolution devices are required for many purposes, as for instance, in remote sensing applications or for medical purposes, different authors have propose divers approaches able to provide super-resolved images of objects [1,2]. In addition, modern imaging systems also include Charge-Coupled Devices (CCD) for performing the caption of the final image. This devices lead to an extra resolution reduction caused by the geometrical properties of pixel. In particular, sampling pixels size, shape and pitch arises as the main resolution limitations [3-5].The image information of an object is not the unique relevant feature for some applications, but also their polarimetric content may be important. For instance, in medical applications, the polarimetric images of a sample may provide extra information which is hidden in regular images [6,7]. To cover such necessity, image polarimeters, as those described in ref. [8,9], are the main devices used to perform polarimetric images of samples.In this work we present a new experimental set-up, based on the use of liquid crystal (LC) technology, which is able to provide at the same time super-resolved images and polarimetric images of a sample, combining in a single arrangement two a priori different systems. In particular, on the one hand, it helps to overcome, to certain extent, the image resolution limitation originated by the CCD pixels pitch. This attainment is achieved by properly addressing different linear phases to an accurately calibrated Liquid Crystal on Silicon (LCoS) display, generating in this way, different sub-pixel displacements of the image object at the CCD plane. By properly combining these different imagines, a final super-resolved image of the object is achieved. On the other hand, the set-up also includes a polarization state analyzer, formed by two ferroelectric LC panels followed by a linear polarizer. In this way, and by performing a proper optimization, a complete Stokes image polarimeter is also developed, allowing us to obtain polarimetric images of expanded beams, and so, to obtain important information of their ellipticity, azimuth or degree of polarization spatial dependence.