Our work

Photo Thermo Acoustic Nano-imaging

Photo Thermal Acoustic nano-Imaging (PTAI) makes use of a pulsed optical pump beam (typically a femtosecond laser) to thermally heat a sample surface. This heating results in a propagating stress field inside the material. These waves are reflected depending on the sub surface characteristics (e.g. layer boundaries and inclusions). The resulting reflected stress field contains information about the sub-surface characteristics and is measured using a pulsed optical probe beam.
Principle of Photo Thermal Acoustic imaging
  • TNO is developing a subsurface nano-imagine concept, so-called Photo Thermal Acoustics for nano-Imaging (PTAI). We have shown that imaging 50 nm feature buried 100 nm below the surface is feasible (TNO IP).
  • Further analysis to determine the ultimate lateral and depth resolution is under study. With the use ofhigh-end Finite Element Models (FEM) and optical simulations.
  • A proof of principle test setup will be built to demonstrate the performance of the PTAI for subsurface nano-imaging.


Non-destructive, high resolution 3D imaging solution for semiconductor industry, which directly measures the mechanical properties of the object.


Semiconductor 3D metrology on the mechanical properties and as GHz excitation of samples in combination with AFM inspection.


we have shown the theoretical, simulated feasibility of resolving 50 nm features at  a depth of 100 nm.


Depth resolution of 10 nm with a lateral resolution below the optical diffraction limit of the pump and probe laser.


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