Ccd based optical detector for a confocal microscope

Abstract

An optical detector includes a charge-coupled device (CCD). The CCD comprises an active cell for receiving a narrow beam of incident illumination and generating photoelectrons in response thereto, and a first stage readout register comprising a row of N transfer cells, where N>1. A first stage gate structure transfers charge packets consecutively from the active cell into the first stage readout register, whereby N successive charge packets are read into the N cells respectively of the first stage readout register. N second stage readout registers each comprise M transfer cells, where M>1, and a second stage gate structure transfers N charge packets from the N cells of the first stage readout register into respective first cells of the second stage readout registers and subsequently shifts the N charge packets from the respective first cells of the second stage readout registers to respective Mth cells thereof. A multiplexer has N inputs coupled respectively to the Mth cells of the second stage readout registers. The multiplexer is operative to connect a selected input to its output. The multiplexer provides an output signal that varies in accordance with variation in intensity of incident illumination on the active cell.