The
system images the volume of a turbid medium and detects the contents. The medium can be water or air, or living tissue, or almost any other material which is at least partially light-transmissive. The
system includes a
light source for producing a series of discrete fan-shaped pulse beams that are substantially uniform in intensity or have been peaked at the edges of the fan to illuminate sections of the medium, a streak tube with a large, thin-slit-shaped
photocathode for collecting the maximum amount of light from weak returns, a field-limiting slit disposed in front of the
cathode for removing multiply
scattered light, a large-aperture optical element for collecting and focusing the reflected portions of the
pulse beam on the field-limiting slit and the
cathode, and an array of detectors. A volume display of the medium is generated by translating the
transmitter and
receiver normal to the longitudinal axis of the
pulse beam, to illuminate adjacent sections of the medium, and combining the sections to provide a volume display. All, or substantially all, of the light returned from each
pulse beam is used. Vehicle motion can be used to provide the scan of the beam. Applications range from foggy
sky surveillance at multiple-kilometer scale to location of fractional-
millimeter tumors in a
human breast.