Abstract: A plurality of electrodes are mounted within a hood positionable over a subject's hed to form an array of concentric electrically conductive electrode rings. The rings can be applied to an outer surface of an electrically insulating liner insertable within the hood. The array preferably comprises five rings mounted within the hood to subtend a 90° arc on both sides of a central perpendicular axis of the hood. The four upper electrodes each subtend an arc of about 15° and the fifth (lower) electrode subtends an arc of about 6°, with 6° arc gaps between each pair of electrodes on either side of the central perpendicular axis. A voltage pulse signal generator's output signal is connected across the two upper electrode pairs, with alternate electrodes being connected to one of the two output terminals of the voltage pulse generator. A voltage divider applies a reduced voltage signal to the lower electrode.

Abstract: A plurality of electrodes are mounted within a hood positionable over a subject's head to form an array of concentric electrically conductive electrode rings. The rings can be applied to an outer surface of an electrically insulating liner insertable within the hood. The array preferably comprises five rings mounted within the hood to subtend a 90.degree. arc on both sides of a central perpendicular axis of the hood. The four upper electrodes each subtend an arc of about 15.degree. and the fifth (lower) electrode subtends an arc of about 6.degree., with 6.degree. arc gaps between each pair of electrodes on either side of the central perpendicular axis. A voltage pulse signal generator's output signal is connected across the two upper electrode pairs, with alternate electrodes being connected to one of the two output terminals of the voltage pulse generator. A voltage divider applies a reduced voltage signal to the lower electrode.

Abstract: A system for establishing a base between a light projecting station and a light receiving station of a triangulating coordinate finder incorporates a target on the light transmitting station and a reflector appropriately positioned relative to a photo sensitive receiving array in the light receiving station. A beam of light is directed through a peep hole through the target onto the reflector and is reflected back onto the target. By adjusting the relative orientation of the two stations so that the light beam is reflected back from the reflecting surface in a direction substantially co-axial with the beam of light projecting through the peep hole the bases of the two stations are arranged to be substantially in the same plane and on a base line. The base length between the two stations is measured and the orientation of the projected beam and the focal axis of the receiving station are established relative to the base line to provide coordinates for the triangulating coordinate finder.