Coherent anti-Stokes Raman scattering (CARS) spectroscopy primarily was used in chemistry, physics and related fields. It is sensitive to the same vibrational signatures of molecules as seen in Raman spectroscopy, typically the nuclear vibrations of chemical bonds. Unlike Raman spectroscopy, CARS employs multiple photons to address the molecular vibrations, and produces a signal in which the emitted waves are coherent with one another. As a result, CARS is orders of magnitude stronger than spontaneous Raman emission. CARS is a third-order nonlinear optical process involving three laser beams: a pump beam of frequency ω pump , a Stokes beam of frequency ω Stokes and a probe beam at frequency ω probe. Read more. 

These beams interact with the sample and generate a coherent optical signal at the anti-Stokes frequency ω CARS = ω pump – ω Stokes + ω probe . The CARS signal ω CARS is resonantly enhanced when the difference between the pump ω pump and Stokes ω Stokes frequencies matches a vibrational transition ω vib of the molecule.

Combining of coherent anti-Stokes Raman scattering (CARS) spectroscopy with the microscopy opens up unique method for chemical imaging. CARS microscopy permits vibrational imaging with high-sensitivity, high speed, and three-dimensional nearly diffraction limited spatial resolution.

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Powerful and versatile tool for vibrational spectroscopy and chemically selective imaging:

  • Label-free optical imaging
  • Minimally invasive technique
  • Non-photobleaching signal
  • 3D sample imaging capability
  • NIR pump and Stokes wavelengths suitable for deep-tissue imaging
  • Picosecond pulse duration – good compromise between efficiency and spectral resolution
  • Sensitive to vibrational signatures of molecules
  • High spectral resolution.
  • Sub-wavelength spatial resolution
  • F-CARS, E-CARS, P-CARS detection geometries
  • Wide range of accessible (molecular) vibrations: 740-4000 cm⁻¹


  • Wide range of accessible vibrations: 740-4000 cm⁻¹
  • Minor fluorescence interference
  • High spectral resolution and sensitivity
  • Sub-wavelength spatial resolution
  • F-CARS, E-CARS, P-CARS detection geometries
  • Easy transformable to fluorescence, TPEF and SHG microscopes
  • Up to 1300 μm excitation for TPEF
  • Specially designed cost-effective picosecond tunable laser system


  • Species selective spectroscopy and microscopy
  • Multimodal nonlinear imaging
  • Deep tissue in vivo imaging
  • Long term live cell studies
  • Non-destructive research for the biological and material sciences
  • Your application is welcome…

cars principle

Coherent anti-Stokes Raman scattering Spectroscopy principle