Topographic optical profilometry of steep slope micro-optical transparent surfaces

Area of Science:

• Optical metrology
• Surface characterization
• Microscopy

Background:

• Reflective optical profilometers struggle with steep slopes and high curvature due to light reflection issues.
• Common techniques like confocal microscopy and interferometry can produce artifacts or blind spots on challenging surfaces.

Purpose of the Study:

• To introduce and validate a novel optical profilometry technique, TOPAF, for micro-optical surfaces.
• To develop a model for TOPAF under micro-optical observation with high numerical aperture objectives.

Main Methods:

• Utilizing an absorbing fluid to fill the gap between a reference and the sample surface.
• Comparing transmission images at two spectral bands to generate topographic data.
• Developing an analytical model for high numerical aperture micro-optical observation.

Main Results:

• TOPAF effectively overcomes limitations of reflective profilometry for steep and curved surfaces.
• The technique provides reliable topographic maps with nanometric height resolution.
• Analytical and experimental results validate the method's performance.

Conclusions:

• TOPAF offers a robust solution for accurate surface profiling of complex micro-optical components.
• The developed model enhances the applicability of TOPAF in micro-optical metrology.
• This technique enables high-resolution surface characterization where traditional methods fail.