Fiber optic and endoscopic LDA systems

The feasibility of fiber optic links between the laser, optical system and photomultiplier of a laser Doppler anemometer system was studied using a conventional backscatter system, a 'Selfoc' coherent fiber between the laser and the optical system, and an ordinary fiber waveguide between the optical system and the photomultiplier. The problem of coupling at the end of the fiber was solved by using an intermediate immersion oil for the coherent fiber, and direct coupling after the field aperture for the waveguide. A three-component backscattering LDA system was then developed using three wavelengths.