text: Laser Doppler velocimetry is often chosen over other forms of flow measurement because the equipment can be outside of the flow being measured and therefore has no effect on the flow. Some typical applications include the following:
  *Wind tunnel velocity experiments for testing aerodynamics of aircraft, missiles, cars, trucks, trains, and buildings and other structures
  *Velocity measurements in water flows (research in general hydrodynamics, ship hull design, rotating machinery, pipe flows, channel flow, etc.)
  *Fuel injection and spray research where there is a need to measure velocities inside engines or through nozzles
  *Environmental research (combustion research, wave dynamics, coastal engineering, tidal modeling, river hydrology, etc.).
  One disadvantage has been that laser Doppler velocimetry sensors are range-dependent; they have to be calibrated minutely and the distances where they measure has to be precisely defined. This distance restriction has recently been at least partially overcome with a new sensor that is range independent.