Optical and Acoustic Systems for Fluids

Laser Doppler Anemometry

3D-MeasurementsDoppler effect(ive)
Laser Doppler Anemometry (LDA) is an optical technique for non-intrusive 1D, 2D and 3D point measurement of flow velocity, turbulence and other flow characteristics based on the Doppler effect causing the frequency shift of the scattered light. It allows for a clearer understanding of fluid mechanics, especially in the field of sediment flow. Furthermore, LDA can be used for the accurate calibration of flow measurements as a reference.

3D-LDA systems Flow Explorer from Dantec Dynamic.
Calibrated 2D Flow Explorer system with 2x continuous wave diode-pumped solid-state (DPSS) laser and a BSA processor F600

  • Laser power P0 = 2 x 500 mW
  • Laser wavelengths λ = 532 and 561 nm
  • Focal lengths f = 300, 500, 750 mm
  • Beam spacing 60 mm
  • Probe volume length/diameter 0.7/0.1 – 4.6/0.7 mm/mm
  • 12 bit FFT burst spectrum analyzer 120 MHz and 80 MHz Bragg-cell shift
  • Velocity range -150 – 650 m/s
  • Optical fiber probes for subaquatic use with f = 500 and 250 mm

3D-MeasurementsCalibrated 1D Flow Explorer system with DPSS laser and BSA processor F600

  • Laser power P0 = 35 mW
  • Laser wavelengths λ = 660 nm
  • Focal length f = 300 mm
  • Beam spacing 60 mm
  • Probe volume length/diameter 0.7/0.1 mm/mm
  • 12 bit FFT burst spectrum analyzer 120 MHz and 80 MHz Bragg-cell shift
  • Velocity range -90 – 220 m/s

BSA Flow Software v. 5.20

  • Control of LDA systems and other peripherals, data acquisition and processing, data post-processing and visualization

Automated 3D traversing system 1010 mm x 1010 mm x 1010 mm
Repeatability better than 0.017 mm, adjustable velocity of movement.


Acoustic Side-facing Doppler System

AcousticSide-LookingDopplerSystemFlow mechanics when it’s getting turbid.
The Acoustic Side Looking Doppler System is an excellent alternative for measuring flow velocities in turbid flows where light-based techniques reach their limitations. Using the Doppler effect, the system provides velocity profiles consisting of nine 2D velocity vectors.

OTT Side-facing Doppler probe

3x OTT SLD Sensor

  • Ultrasonic frequency 2MHz
  • Velocity range +/- 10 m/s
  • Profiling range max. 10 m
  • Measurement cell size 0.2 – 2 m
  • Measurement cell number max. 9
  • Water level sensor

OTT SLD EasyUse Software

  • Processing of stream-wise and span-wise velocities, computing of discharge

OTT netDL data logger

  • In-situ data acquisition, logging and transfer

4x pressure probe OTT PLS

  • Relative water level 0 – 4 m


Optical Turbidity Measurement System

16_Optical_TurbidityMore information on suspended material.
The Optical Turbidity Measurement System implements the light scattering method. The calibrated system gives accurate data in a wide range of FNU or gram per liter units. In general, turbidity represents an important variable relating to sediment flows and provides supplementary information about the quantity of suspended material.

HachLange Solitax system
4x turbidity probe Solitax ts-line sc with the IR-double light scattering method (ISO 7027)

Measurement range

  • 0.001 – 4000 FNU or 0.001 – 50 g/l
  • with automatic wiper

2x Controller sc200

  • For installed and field applications



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