Eye-safe Squeezed-Light-Enhanced Scanning Heterodyne Mach-Zehnder LDV

Eye-safe Squeezed-Light-Enhanced Scanning Heterodyne Mach-Zehnder LDV

in the DFG project ”Eye-safe Sensitivity Enhancement of Laser-Doppler-Vibrometry based on Squeezed Light”

State of the art / Motivation

  • A laser Doppler vibrometer (LDV) is a well-established industrial instrument that is used to make non-contact vibration measurements of a surface and path length changes through media.
  • Industrial LDV can used to measure the sound field in gas, liquid or transparent solid by refractive tomography.
  • According to the DIN / IEC 60825 laser safety norm, laser radiation with a wavelength greater than 1.4 μm and below 10 mW is classified as “Class 1”, which means eye safety.
  • Although the industrial LDV of laser safety class I avoids the cost of laser safety personnel, the measurement resolution is also limited due to the limitation of laser intensity and power.
  • Due to the new systematic measurement errors caused by the thermal deformation of optical components and samples, there is still an upper limit to the resolution improved by increasing the optical power.
  • The team of Professor Dr. Roman Schnabel at the University of Hamburg as the project partner realized the first squeeze light source for gravitational waves (GW) detector (Michelson interferometers) and increased its sensitivity level.


  • Proof of the concept of squeezed-light-enhanced LDVy
  • Breaking the resolution limit of modern industrial eye-safe LDV with the help of squeezed-light technology
  • Exploration of the potential of the laser interferometric refractive tomography with a significantly improved resolution for the research on currents and sound fields in fluids and solids


  • Development of a new heterodyne LDV suitable for integration with squeezed-light sources (the portable light source for squeezed vacuum states at 1550 nm will be built by the team of Professor Roman Schnabel)
  • Realization of a robust demonstrator for refractive tomography of sound waves using squeezed-light heterodyne LDV
  • Development of software for the tomographic reconstruction of the 3D distribution of the refractive index
  • Determination of the sensitivity of the squeezed-light-enhanced scanning heterodyne Mach-Zehnder LDV

Mengwei Yu, M.Sc.

Scientific Assistant

E-Mail: yu@iei.tu-clausthal.de