On-line surface inspection using cylindrical lens-based spectral domain low-coherence interferometry.

Area of Science:

• Optical Metrology
• Surface Metrology
• Interferometry

Background:

• Traditional surface inspection methods often lack the speed and resolution required for real-time, large-scale applications.
• Existing spectral interferometry techniques may be limited in measuring extended surface profiles.

Purpose of the Study:

• To introduce and validate a spectral domain low-coherence interferometry (SD-LCI) method for efficient online surface inspection.
• To demonstrate the capability of measuring long profiles and achieving real-time 3D surface mapping.

Main Methods:

• Implementation of a Michelson interferometric configuration using cylindrical lenses as objective lenses.
• Integration of high-speed CCD camera, GPU, and multicore processors for fast data acquisition and processing.
• Utilizing a fast Fourier transform algorithm for interferogram analysis and employing sample translation for real-time inspection.

Main Results:

• Successful measurement of two step height surfaces with high accuracy.
• Generation of 2D profile results and 3D surface maps that closely match manufacturer specifications.
• Demonstration of large-scale 3D surface measurement and real-time surface inspection capabilities.

Conclusions:

• The presented SD-LCI method offers a powerful and efficient solution for online surface inspection tasks.
• The system's ability to perform single-shot measurements and real-time 3D mapping makes it suitable for industrial applications.
• The use of cylindrical lenses and advanced computing technology enhances measurement range and speed.