Advantages and disadvantages of LDA | Laser Doppler Aneamometer
This page covers advantages and disadvantages of LDA (Laser Doppler Aneamometer). It mentions LDA advantages or benefits and LDA disadvantages or drawbacks.
Introduction:
In this instrument, laser beam is focused at a point where velocity is to be measured.
The light is scattered by tracer particles which are present in the fluid.
The scattered light is observed by photodetector used in the circuit design.
In LDA, velocity of tracer particles is equal to fluid velocity. This causes doppler shift of scattered light frequency. This produces photodetector signal proportional to fluid velocity.
The velocity of flow can be expressed using following equation.
➨ f = (2*V*sin(θ/2))/λ
Where,
λ = Wavelength of laser beam in the fluid
V = Velocity of fluid flow
Benefits or advantages of LDA (Laser Doppler Aneamometer)
Following are the benefits or advantages of LDA (Laser Doppler Aneamometer) :
➨It has high frequency response which is in the order of MHz.
➨It can be used to measure flow of liquids and gases both.
➨It can be used to measure blood flows in biomedical domain.
Drawbacks or disadvantages of LDA (Laser Doppler Aneamometer)
Following are the disadvantages of LDA (Laser Doppler Aneamometer) :
➨The method can not be employed for clean flow measurement.
The insertion of tracer particles is necessary.
➨Error may occur if velocity of beam scattering particles is
not equal to flow velocity of fluid.
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