Measurement of the fluid-velocity profile using a self-mixing superluminescent diode

A novel optical Doppler velocimeter using a self-mixing superluminescent diode is proposedand demonstrated. The operation mechanism uses the photodiode on the back-face of acommercial superluminescent diode to detect the Doppler signal from an interferometer.Thanks to the low coherence length of the optical source, the position of the measuring volumecan be easily moved into the sample under test by adjusting the reference arm length, thusallowing us to measure the velocity profile of the flowing scatterers even in turbid media. Theproposed velocimeter is expected to have several industrial as well as medical applications.