An enhancement of contrast between healthy and neoplastic zones in Mueller matrix images of excised cervical tissue was demonstrated in our prior work for the visible wavelength range. In this paper we present the statistical analysis of Mueller polarimetric data for the diagnostics of high grade cervical intraepithelial neoplasia. The results of linear and non-linear post-processing compressions of the full Mueller matrix are discussed and compared in terms of diagnostic performance. The final goal of these studies is to estimate and compare the diagnostic usefulness of 16 polarimetric measurements required for the reconstruction of complete Mueller matrix of a sample, while looking for an optimal design of future imaging protocols.
We compare four passive polarization imaging configurations by quantitatively assessing their target detection performance for different kinds of noise. Through closed-form expressions we determine the gain of these configurations compared to intensity imaging in the case of target/backrgound discrimination. For three of these configurations we show that a minimum amount of polarimetric contrast between the target and the background is required to outperform intensity imaging. We show that the only configuration that has always better performance requires to use a polarizing beamsplitter and assumes that the main source of perturbation is the background shot noise. This work has interesting perspectives for imaging architecture design.
We describe an active polarimetric imager with laser illumination at 1.5 µm that can generate any illumination and analysis polarization state on the Poincar sphere. Thanks to its full polarization agility and to image analysis of the scene with an ultrafast active-contour based segmentation algorithm, it can perform adaptive polarimetric contrast optimization. We demonstrate the capacity of this imager to detect manufactured objects in diﬀerent types of environments for such applications as decamouﬂage and hazardous object detection. We compare two imaging modes having diﬀerent number of polarimetric degrees of freedom and underline the characteristics that a polarimetric imager aimed at this type of applications should possess.
For the sake of polarimetric accuracy, polarization imaging systems based on liquid crystal modulators often work at one given wavelength due to the strong chromatic properties of the liquid crystal retarders. This often requires the use of narrowband filters which reduces the amount of light in the system and thus the signal-to-noise ratio. For applications where the main parameter of interest is the target/background discriminability rather than polarimetric accuracy, spectral filtering may not be the best option. In this work, we investigate the impact of broadening the spectrum of the light entering the system on the discriminability performance of passive and active polarimetric systems. Through simulations, we show that broadening the bandwidth of the illumination can increase the contrast between two regions, as the increase of light flux compensates for the loss of polarimetric precision. Moreover, we show that taking into account the chromatic characteristics of the components of the imaging system can further enhance the contrast. We validate these findings through experiments in passive and active configurations, and demonstrate that the illumination bandwidth can be seen as an additional parameter to optimize polarimetric imaging set-ups.
We describe an experiment that allows distant users to perform a labwork using Erbium Doped Fiber Amplifier (EDFA) in order to understand the basics physics and engineering involved. The EDFA and the measurement instrumentation are specially designed so as to allow for remote control through the web. The purpose of the project can then be distant learning for students from developing countries which cannot afford this kind of high-cost equipment.