Extended Phase Shifting Interferometry (ePSI) is an optical metrology technique that integrates the strengths of Coherence Scanning Interferometry (CSI) and Phase Shift Interferometry (PSI) to enable high-precision surface topography measurements across an extended vertical range.

The ePSI technology overcomes the limitations of PSI and CSI by combining their strengths:

  Hybrid acquisition: Combines phase-shifting interferometry with controlled vertical scanning or coherence-based height localization.
  Extended range: Expands the measurable vertical range to values such as CSI while retaining PSI’s vertical sensitivity.
  Nanometric precision: Maintains sub-nanometric vertical resolution under controlled conditions.

The ePSI is particularly effective for surfaces that combine ultra-smooth regions with significant height variations, making it highly suitable for semiconductors, optics, and precision engineering.

Extended Phase Shifting Interferometry (ePSI) is instrumental in scenarios where both ultra-high precision and extended vertical range are required. It is widely applied in:

  Semiconductor inspection: Measurement of wafers, multilayer structures, and silicon carbide surfaces with stepped features.

  Optics manufacturing: Characterization of polished lenses, mirrors, and thin-film coatings with sub-nanometric accuracy.

  Precision engineering: Quality control of critical components that combine fine surface details with larger height variations.

  Materials science: Analysis of surfaces where both nanometer-scale features and micro-scale steps must be accurately captured.

  Research and development: Flexible metrology for advanced studies on smooth, complex, or hybrid surfaces.