Abstract: The present invention concerns a method and system for in vivo spatial measurement of density and relative proportions of retinal visual pigments. The method involves the steps of illuminating a retina with light of a given intensity and wavelength, acquiring the residual light coming from the retina using a photosensing device having an array of pixels, attributing a residual intensity to each pixel thereby producing a corresponding spatial image of the retina, and posing an equation relating the residual intensity to a number of unknown variables of interest. The above steps are repeated using light of a different wavelength but same intensity to acquire a set of spatial images and a set of corresponding equations for each pixel of each image. For each pixel of each image, the set of equations is solved for the unknown variables obtaining the spatial measurement of density and relative proportions of retinal visual pigments.

Abstract: A circuit and a method for compensating the floating differential capacitance appearing between two recording microelectrodes is presented. It is shown how this floating capacitance can be neutralized so that current in any microelectrode can be injected without any significant cross-talk picked up by the other. It is a fully symmetrical compensation.