version of the output beam 16 the amount of phase shift being equivalent to the round trip distance between the transmitter and the receiver in this implementation the return signal 18 is converted to a modulated electron stream 36 by action of a photocathode 34 the electron stream 36 impinges on a thin conductive sheet 38 accelerated by a periodic voltage from a source 40 which is added to a dc voltage v2 the result is that the amplitude of the electron stream 36 is determined by the amount of light striking the photocathode whereas the kinetic energy of the electrons making up said electron stream is determined by the sum of v2 and the periodic voltage obtained from source 40 the kinetic energy of the electrons making up the electron stream 36 will determine the gain of the multichannel plate 44 which through secondary emission of electrons amplifies the electron stream 36 when said amplified electron stream emerges from the multichannel plate it impinges on a phosphor plate 46 which converts the electron stream back into a photon image the modulation of this photon image is the result of beating the received light 18 by the voltage controlled gain of the multichannel plate and hence contains information concerning the phase shift of the signal this photon image is detected by a ccd detector array 50 these detectors integrate the magnitude of the photon image for a given period of time most simply an integral period of the modulation frequency and this intensity information is then read out to range processor 32 for range determination the problem of obtaining range information from a scannerless system comprising.