| 摘要 |
PURPOSE:To make it possible to measure the speed of matter with high accuracy, by converting coherent light to laser beam having a converging region, a waist region and a diffusion region by an optical system and arranging moving matter to the waist region to receive laser beam at a speckle boiling position. CONSTITUTION:A numeral 11 shows a laser beam source for emitting coherent laser beam and a numeral 12 shows an projection optical system for converting laser beam from the laser beam source 11 to laser beam having a converging region, a waist region and a diffusion region. A numeral 13 shows pervisous moving matter arranged at the waist position of laser beam. When the matter 13 to be measured moves at a speed V, a speckle is brough to a boiling state at the opening part 16 separated by a distance R from the matter 13. A variation signal is converted to an electric signal by a photoelectric converter element 14 and a speed is detected with high accuracy by a signal processing part 17.
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