HGL Dynamics Laser Vibrometry – Selection Guide

Single Point Laser Doppler Vibrometer (LDV)



Overview of the Laser Vibrometry System

The laser beam of the Scanning Laser Doppler Vibrometer is deflected by two mirrors which are controlled by a computer. A built-in video camera delivers an image of the object under test. On this picture, the measurement points can be arranged with CAD software. After the initial setup of the points, the measurement is done automatically by the computer.

Nearly all components of a conventional Scanning Laser Doppler Vibrometer are built into a single optical unit that is structurally complex and therefore expensive. The Vibrolaser ScanSet now overcomes these restrictions and delivers a very high level of performance in measuring. What’s more, it simply upgrades an existing single-point laser vibrometer to a fully equipped scanning laser vibrometer system.

Simply fix your existing LDV (or a new one, if you have none) with the quick release clamps, adjust the mirror unit using the linear slides provided, and you are ready to start measuring. The Vibrolaser ScanSet is shipped with a data acquisition system with 4 analogue input channels to measure the laser signal and any other reference signals. The user-friendly measurement and analysis software quickly processes the vibration data, giving graphical display of the values and animation of the mode shapes.

Benefits of the Laser Vibrometry System

· It is a non-intrusive vibration measuring method

· Overcomes the effect of mass loading of the test structure or object, which is important for lightweight structures/objects.

· Very sensitive – can detect tiny velocity vibrations down to 2.5 nm/s (i.e., 2.5 x 10-6 mm/s = 0.0000025 mm/s)

· High velocity bandwidth – can typically measure from 1 mm/s to 2,000 mm/s velocity bandwidth

· High displacement bandwidth – can typically measure from 1 μm to 100 mm displacement bandwidth

· Has a large maximum frequency of 1 MHz

· Can have a large physical “standoff” from the surface of the object under test – i.e. typically up to distances of 200 metres

· Good spatial resolution (i.e., how well lines can be resolved in an image)

·  Can measure the velocity of any kind of structure – rotating of ‘static’.

·  Utilising ‘Electron Speckle Patterns, can be used as strain gauge work (with twin lasers)

·  Reduced testing time, no time wasted on instrumentation hardware installation, as well as a reduction in manpower required and therefore cost

·  Normally measures in velocity, but can be ‘converted’ to either acceleration or displacement.

·  Carrying out Operational Deflection Shapes (ODS) studies of the scanned surface

·  Mode shapes can be analysed.

·  Torsional vibration can be measured (requires two lasers for this)

·  No physical sensors required to carry out measurements – this is done by the laser beam and system without physical contact with the object under test.

Technical Specifications of HGL’s Leading Laser Vibrometry Products

  • Single Point Laser Doppler Vibrometer … Learn More
  • Scanning Laser Doppler Vibrometer (SLDV) … Learn More