Tilt metrology on rough dielectric surfaces using low coherence scanning interferometry.
Optics Express
|December 28, 2019
Summary
This study introduces a new low coherence scanning interferometry (LCSI) method for precise surface profiling and tilt measurement of rough dielectric surfaces. The technique offers improved precision over conventional methods, crucial for applications like smartphone camera manufacturing.
Area of Science:
- Optical Metrology
- Surface Science
- Interferometry
Background:
- Accurate surface characterization is vital in precision manufacturing, especially for dielectric materials.
- Existing methods for measuring surface topography and tilt can lack precision for micro-scale roughness.
- The demand for high-resolution dimensional and tilt information is increasing in industries like optics and semiconductor manufacturing.
Purpose of the Study:
- To develop and validate a novel technique for simultaneously measuring the dimensional surface profile and tilt of rough dielectric surfaces.
- To enhance measurement precision for micro-scale roughness and tilt angles.
- To assess the applicability of the proposed method in practical manufacturing scenarios, such as smartphone camera module production.
Main Methods:
- Utilizing low coherence scanning interferometry (LCSI) with a compound light source (superluminescent light-emitting diode and ytterbium-doped fiber amplifier).
- Employing principal component analysis (PCA) and a centroid peak detection algorithm for extracting tilt angle and direction from surface data.
- Validating the method using standard angle gauge blocks and certified step height samples.
Main Results:
- The proposed LCSI technique successfully obtains both dimensional surface profile and tilt information for rough dielectric surfaces.
- Measurement precision for tilt was approximately three times superior to conventional auto-collimators in smartphone camera module manufacturing.
- The method demonstrated potential for dynamic tilt evaluation of moving objects.
Conclusions:
- The developed LCSI technique provides a highly precise and effective solution for characterizing surface topography and tilt of rough dielectric materials.
- This advancement offers significant improvements over existing methods, particularly for high-precision manufacturing applications.
- The technique shows promise for future applications, including real-time monitoring of dynamic processes.
