SonTek / YSI
SonTek/YSI makes 2D and 3D ADCP/ADP Acoustic Doppler Current Profilers, ADV velocimeters, DVL speed logs, and Argonaut currentmeter water velocity sensors
http://www.sontek.com/

Signal Processing SA (Switzerland)
With our ultrasonic velocimeter you could measure velocity profile in real time in almost all liquid
http://www.signal-processing.com/index.htm

Polytec
vibration measurement, vibrometry, non-contact measurement, nondestructive testing, quality control, machine vision, radiation measurement, sensors, distributor, representative, optical spectroscopy, lifescience, semiconductor, MEMS, automotive
http://www.polytec.com/