Early diagnosis of glaucoma, which is a leading cause for visual impairment, is critical for successful treatment. It has been shown that Imaging polarimetry has advantages in early detection of structural changes in the retina. Here, we theoretically and experimentally present a snapshot Mueller Matrix Polarimeter fundus camera, which has the potential to record the polarization-altering characteristics of retina with a single snapshot. It is made by incorporating polarization gratings into a fundus camera design. Complete Mueller Matrix data sets can be obtained by analyzing the polarization fringes projected onto the image plane. In this paper, we describe the experimental implementation of the snapshot retinal imaging Mueller matrix polarimeter (SRIMMP), highlight issues related to calibration, and provide preliminary images acquired from the camera.
Phase error is common in reflective interferometers, such as the Michelson. This yields highly asymmetric interferograms that complicate the post-processing of single-sided interference data. Common methods of compensating for phase errors include the Mertz, Forman, and Cannes phase correction techniques. However, birefringent interferometers often have highly symmetric interferograms; thus, compensating for phase errors may represent an unnecessary and/or detrimental step in post processing. In this paper, an analysis of the phase error generated by the Infrared Hyperspectral Imaging Polarimeter (IHIP) is conducted. First, a model of the IHIP is presented that quantifies the phase error in the system. The error associated with calculating spectra from single-sided interferograms, using Mertz phase correction and simple singlesided to double-sided mirroring, is then investigated and compared to "true" double-sided Cannes phase corrected spectra. These error calculations are set within the context of measurements taken from a Michelson interferometer-based Fourier transform spectrometer. Results demonstrate that the phase error of the IHIP is comparatively small and that Mertz phase correction may not be necessary to minimize error in the spectral calculation.