Microphotography of shocks in crystals

摘要

Recent advances in high-speed photographic capabilities of Micro Detonics Facility ((mu)DF) and miniature electric gun drivers have allowed real-time stop motion examination of shock waves passing through single crystals. Examination of defects and growth of dislocations from >5 GPa shocks, requires temporal resolutions of a nanosecond or better and spatial resolutions better than 10 (mu)m. As the defects and dislocations are highly inhomogeneous, simultaneous frame and streak records of the same location within the crystal are also required. Cameras and laser illuminators, discussed previously, have been upgraded and combined into a coaxial streak and frame system. Both laser beams are tailored and aimed separately. The dye laser is spatially: filtered and focused to cover the frame. The argon laser is focused to a line on the target which is then imaged to the streak camera slit. The ability to see the focal line of the argon laser on the frame camera allows precise collocation of the fields of view of the two cameras. The focused argon laser and the slit are confocal resulting in the ability to obtain good streak data for crystals of poor optical quality.