Fiber-optic Doppler Velocimeter Research Articles

Interferometric fiber-optic Doppler velocimeter with high-dynamic range

We describe and demonstrate a fiber-optic laser Doppler velocity sensor which is based on interferometric processing of a wavelength encoded signal. The range of the fiber-optic velocimeter is scalable from less than 1 mm/s up to 1000 m/s through changes in the optical path imbalance in the fiber-optic interferometer. A dynamic velocity resolution of <80 /spl mu/m/s//spl radic/Hz is demonstrated.

Fiber-optic Doppler velocimeter that incorporates active optical feedback from a diode laser

A fiber-optic Doppler velocimeter that incorporates the effect of self-mixing in a diode laser is described. A theoretical model, based on self-mixing interference theory, is presented, and a simple experimental arrangement is constructed. The results of the experimental research are found to be in good agreement with the theoretical analysis. A Doppler velocity of as much as 3 m/s was measured directly, and a good linear relationship between the Doppler velocity and the Doppler-shifted frequency was obtained, which can be used to determine the speed of a moving object.

Probing a fluid through a distorting interface using a monostatic fiber-optic Doppler velocimeter

A theoretical and experimental study is presented of a Doppler velocimeter that uses a single-mode optical fiber to transmit the probe beam and collect the signal light. The performance is discussed in two cases: (i) for negligible and (ii) for strong probe beam distortion caused by surface scattering. The results suggest that in medical use the assessment of blood velocity is possible for thin superficial vessels.

New monostatic balanced Doppler velocimeter using a high birefringence fiber

A novel fiber-optic Doppler velocimeter is presented. By suitably controlling the polarization state of the local oscillator, illuminating beam, and signal light, balanced mixing with a noise reduction of 30 dB as compared to unbalanced mixing can be realized. The remaining noise level is predominantly due to shot noise. Allowing for losses in the receiving optics and for nonperfect mixing efficiency, the minimum detectable signal power is estimated to be 10/sup -18/ W-Hz/sup -1/. The high sensitivity of the system is demonstrated by the detection of light scattered from a distant moving object.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>