Dual-wavelength digital holography with a single low-coherence light source

Area of Science:

• Optical Metrology
• Surface Characterization
• Nanotechnology

Background:

• Accurate measurement of micro- and nanostructures is crucial for advanced manufacturing and scientific research.
• Existing surface topography measurement systems often face limitations in axial range, image quality, and cost.

Purpose of the Study:

• To develop an advanced measurement system for micro- and nanostructure surface heights.
• To improve axial step-measurement range and image quality.
• To enable cost-effective and compact surface topography analysis.

Main Methods:

• Utilizing dual-wavelength digital holography and low-coherence interferometry.
• Employing a single light-emitting diode (LED) to generate two distinct wavelengths via filtering.
• Implementing a simplified system configuration with single-source lighting.

Main Results:

• Demonstrated capability to measure surface profiles with higher step heights.
• Achieved reduced speckle noise for improved image quality.
• Verified system performance using experimental results on a standard step sample.

Conclusions:

• The proposed system offers an extended axial measurement range and superior image quality.
• The dual-wavelength approach enables compact, lower-cost surface topography measurement solutions.
• The system is applicable across various scientific and industrial fields requiring precise surface analysis.