A spatio-temporally incremental fiber sweep source comprising: a light pulse generator for generating light pulses; a fiber array (24, 30) of individual optical fibers having an input end (21, 32) and an output end (23, 34), the optical fibers at the input end (21, 32) being packaged in a round shape with a random order and being arranged to receive the light pulses substantially simultaneously, the optical fibers at the output end (23, 34) being packaged in a rectangular raster scan pattern wherein the optical delay in each optical fiber is controlled by controlling the fiber lengths and is greater than in the previous optical fiber in the scan pattern direction whereby light exits the array (24, 30) in the raster scan pattern as a sweep source; and a fiber collimator and a free-space telescope comprising two optical lenses arranged to expand the beam size of the fiber collimator to match an input aperture of the fiber array (24, 30), wherein the fiber collimator receives the light pulses from the light pulse generator and passes them to the free-space telescope, which in turn directs them to the input of the fiber array (24, 30); wherein the light pulse generator comprises: a fiber ring cavity arranged to perform polarization rotation mode-locking; a laser diode arranged to pump light pulses into the fiber ring cavity; a mode-locker inside the fiber ring cavity to ensure the delivery of ultra-short pulses; a fiber-based optical integrated module arranged to provide wavelength-division multiplexing for pump and signal combining, and optical coupling for signal extraction, said integrated module providing an output pulse from said fiber ring cavity; and a pre-chirp unit arranged to receive the output pulse from the integrated module and chirp ahead the output pulse to compensate for dispersion to be experienced during passage of the light through the fiber array (24, 30), wherein the pre-chirped pulse is launched into the free-space telescope through the fiber collimator. a light pulse generator for generating light pulses; a fiber array (24, 30) of individual optical fibers having an input end (21, 32) and an output end (23, 34), the optical fibers at the input end (21, 32) being packaged in a round shape with a random order and being arranged to receive the light pulses substantially simultaneously, the optical fibers at the output end (23, 34) being packaged in a rectangular raster scan pattern wherein the optical delay in each optical fiber is controlled by controlling the fiber lengths and is greater than in the previous optical fiber in the scan pattern direction whereby light exits the array (24, 30) in the raster scan pattern as a sweep source; and a fiber collimator and a free-space telescope comprising two optical lenses arranged to expand the beam size of the fiber collimator to match an input aperture of the fiber array (24, 30), wherein the fiber collimator receives the light pulses from the light pulse generator and passes them to the free-space telescope, which in turn directs them to the input of the fiber array (24, 30); wherein the light pulse generator comprises: a fiber ring cavity arranged to perform polarization rotation mode-locking; a laser diode arranged to pump light pulses into the fiber ring cavity; a mode-locker inside the fiber ring cavity to ensure the delivery of ultra-short pulses; a fiber-based optical integrated module arranged to provide wavelength-division multiplexing for pump and signal combining, and optical coupling for signal extraction, said integrated module providing an output pulse from said fiber ring cavity; and a pre-chirp unit arranged to receive the output pulse from the integrated module and chirp ahead the output pulse to compensate for dispersion to be experienced during passage of the light through the fiber array (24, 30), wherein the pre-chirped pulse is launched into the free-space telescope through the fiber collimator. a fiber ring cavity arranged to perform polarization rotation mode-locking; a laser diode arranged to pump light pulses into the fiber ring cavity; a mode-locker inside the fiber ring cavity to ensure the delivery of ultra-short pulses; a fiber-based optical integrated module arranged to provide wavelength-division multiplexing for pump and signal combining, and optical coupling for signal extraction, said integrated module providing an output pulse from said fiber ring cavity; and a pre-chirp unit arranged to receive the output pulse from the integrated module and chirp ahead the output pulse to compensate for dispersion to be experienced during passage of the light through the fiber array (24, 30), wherein the pre-chirped pulse is launched into the free-space telescope through the fiber collimator.