Abstract

Laser Doppler velocimeter (LDV) that is proposed firstly by Y. Yeh and H. Z. Cumminsis¹ is a well established technique in many fields such as fluid mechanics and thermal engineering.² It provides remote, absolute and non-invasive measurement of the velocity distribution within a probe volume, with high spatial resolution. However, there are still some problems in the LDV system; its large body, large probe, and high price. In order to solve these problems, the versatility of the technique has been extended by the availity of optical fibers and related components.³ Fiber LDV system have been also developed to enhance the potential of the conventional fixed-type LDV.⁴ In this paper, we have proposed the possibility of the small, light and remote fiber-optic LDV system with a variable directional fiber coupler (DC) in order to measure the velocity of fluids in a quartz dye cell of the dye laser on working and to produce a sufficiently small instrument.

© 1995 IEEE