Scanning monochromatic spatial low-coherence interferometer

Area of Science:

• Optics
• Interferometry
• Materials Science

Background:

• Conventional temporal low-coherence interferometry (T-LCI) is limited in depth discrimination.
• Spatial low-coherence interferometry (S-LCI) offers enhanced capabilities.
• S-LCI utilizes an off-axis converging laser beam for probing.

Purpose of the Study:

• To demonstrate the capabilities of scanning spatial low-coherence interferometry (S-LCI).
• To measure angle-dependent phase shifts and material properties.
• To achieve simultaneous refractive index and thickness determination.

Main Methods:

• Employing a scanning spatial low-coherence interferometer (S-LCI).
• Utilizing an off-axis converging single wavelength laser beam.
• Processing signals and data similar to temporal low-coherence interferometry (T-LCI).
• Accurately scaling incident angles in the Fourier domain.

Main Results:

• Demonstrated angle resolving and depth discrimination capabilities of S-LCI.
• Successfully measured angle-dependent phase shifts from multiple reflections.
• Obtained simultaneous refractive index and geometric thickness of a glass plate.

Conclusions:

• S-LCI provides significant advantages over T-LCI.
• The developed S-LCI method enables efficient, one-step material characterization.
• S-LCI is a powerful tool for precise optical metrology.