Patent ID: 8552429

Claim:
A non-contact charge sensor comprising: a semiconductor detector having a first surface and an opposing second surface, the detector comprising: a substrate having the first surface and the opposing second surface; a high resistivity first surface electrode layer disposed on the first surface; a low resistivity first surface electrode disposed on the high resistivity first surface electrode layer, wherein an area portion of the low resistivity first surface electrode is removed to expose a portion of the high resistivity electrode layer; a low resistivity second surface electrode layer disposed on the second surface of the semiconductor detector, wherein a voltage applied between the first surface low resistivity electrode and the second surface low resistivity electrode causes a free charge to drift toward the high resistivity electrode on the first surface or the low resistivity electrode on the second surface according to a polarity of the free charge and the polarity of the applied voltage; at least one non-contact electrode disposed at a selected distance apart from the exposed portion of the high resistivity first surface electrode layer, the at least one non-contact electrode configured to have a signal induced in it in response to the movement of the free charge within the semiconductor detector, in which the high resistivity first surface electrode layer induces the signal on the non-contact electrode; and a charge sensitive preamplifier coupled to the non-contact electrode to output a signal in response to the movement of the free charge within the detector.