The amount of usefully captured light in an optical system may be increased by concentrating light in a region where it can be collected by the optical system. Sense amplifiers of the IMD are calibrated to correlate the signals to reference sagittal, horizontal and frontal planes of the body. A multilayer system including the HMPSA, an adjacent printable support layer, made of paper or a polymer film, and a protective layer adjacent is also provided. Each side arm for that hinge comprises an elongate side that terminates in a region fitting over the wearer’s ear; and an arcuate region for fitting into the gap between the hinge back wall and connector pin when: positioned at an angle between about 20 and 75 degrees relative to the main frame body; slid into the gap; and rotated about the connector pin away from the main frame. Users to actually receive data can be selected from among active users in a multi-antenna system, and a corresponding precoding matrix and a weighting matrix can be obtained.