Optical device and method for measuring velocity

摘要

In the field of non-intrusive velocity measurement, a device and a method for measuring the velocity of objects, particles or fluid flow is provided. The device comprises transmitter means (1) comprising at least one linear array (101) of surface emitting light sources (102x), said light sources (102) being arranged in a linear configuration spaced apart by a predetermined separation distance (d), an optical system (103-105) including at least one imaging lens directing the substantially coherent electromagnetic radiation (10) emitted from the light sources (102) into a measurement region in a predetermined manner producing an array of fringes or spots (4) spaced apart with a predetermined fringe distance ( LAMBDA ) corresponding to the separation distance (d) between the light sources (102), receiver means (2) comprising light manipulating means (202, 203) directing the electromagnetic radiation (20) scattered from the measurement region to detection means including at least one detector (201, 204, 205) detecting the scattered electromagnetic radiation (20) from the measurement region as an object (3) passes through the measurement region, detector processing means processing the detected signals from the detector means corresponding to the particle(s) and surface (3) passing the fringes (4) in the measurement region. According to the invention, the surface emitting light sources are Vertical Cavity Surface Emitting Laserdiodes (VCSEL). Hereby, a low power consumption is achieved just as a reliable and simple light source is provided resulting in a robust non-intrusive velocity measurement system.