Applications of a streak-camera-based imager with simultaneous high space and time resolution

摘要

Abstract: speed imaging device has been built that iscapable of recording several hundred images over a timespan of 25 to 400 ns. The imager is based on a streakcamera, which provides both spatial and temporalresolution. The system's current angular resolution is16 $MUL 16 pixels, with a time resolution of 250 ps. Itwas initially employed to provide 3-D images ofobjects, in conjunction with a short-pulse(approximately 100 ps) laser. For the 3-D(angle-angle-range) laser radar, the 250 ps timeresolution corresponds to a range resolution of 4 cm.In the 3-D system, light from a short-pulse laser (afrequency-doubled, Q- switched, mode-locked Nd:YAGlaser operating at a wavelength of 532 nm)flood-illuminates a target of linear dimensionapproximately 1 m. The returning light from the targetis imaged, and the image is dissected by a 16 $MUL 16array of optical fibers. At the other end of the fiberoptic image converter, the 256 fibers form a verticalline array, which is input to the slit of a streakcamera. The streak camera sweeps the input line acrossthe output phosphor screen so that horizontal positionis directly proportional to time. The resulting 2-Dimage (fiber location vs. time) at the phosphor is readby an intensified (SIT) vidicon TV tube, and the imageis digitized and stored. A computer subsequentlydecodes the image, unscrambling the linear pixels intoan angle-angle image at each time or range bin. We areleft with a series of snapshots, each one depicting theportion of target surface in a given range bin. Thepictures can be combined to form a 3-D realization ofthe target. Continuous recording of many images over ashort time span is of use in imaging other transientphenomena. These applications share a need for multipleimages from a nonrepeatable transient event of timeduration on the order of nanoseconds. Applicationsdiscussed for the imager include (1) pulsed laser beamdiagnostics - measuring laser beam spatial and temporalstructure, (2) reflectivity monitoring during pulsedlaser annealing of microelectronics, and (3) detonicsor shock wave research, especially microscopic studiesof shocks produced by laser pulses. !33