| 摘要 |
PURPOSE:To obtain a laser Doppler velocimeter from which measurement errors derived from vibrations or stresses applied to an optical fiber or back scattered light, etc., produced in the optical fiber are eliminated. CONSTITUTION:The laser light emitted from a laser light source 10 is transformed to parallel rays 14 through a collimator lens 13 incorporated in a probe main body 2 after the light is propagated through a single-mode optical fiber 12 and split into a transmitted and reflected components by means of a half mirror 15. The light irradiating the surface of an object to be measured 4 is obtained by condensing the light transmitted through the half mirror 15 to the surface of the object 4 through a probe lens 7. The light reflected by the half mirror 15 receives twice frequency deviation by an angular frequency omegao from a frequency shifter 17 while the light makes a round trip between the mirrors 15 and 16 and becomes reference light 18. Scattered light 6 produced from the irradiating light 5 becomes parallel rays through the lens 7, heterodyne- interferes with the reference light 18 at the half mirror 15, and is converted into an electric signal by means of a photodetector 19. |
