Two-dimensional high-speed and long-range tomography and profilometry using liquid-crystal Fabry-Perot resonator

Area of Science:

• Optical Engineering
• Metrology
• Materials Science

Background:

• Low-coherence optical interferometry is crucial for high-resolution surface profiling and depth measurement.
• Expanding the measurement depth of interferometric techniques without sacrificing resolution remains a significant challenge.

Purpose of the Study:

• To develop a two-dimensional, high-speed, long-range tomography and profilometry system.
• To enhance the measurement depth of optical interferometry using a novel low-coherence optical frequency comb generator.

Main Methods:

• Fabrication of a liquid-crystal Fabry-Perot resonator as a low-coherence optical frequency comb generator.
• Real-time acquisition of interference fringes using a CCD camera.
• Calculation of fringe orders based on the tunable refractive index of the liquid crystal.

Main Results:

• Achieved a 9-fold expansion in measurement range (approximately 8 mm depth).
• Obtained a profilometry resolution of 3.7 μm and tomography resolution of 11 μm.
• Demonstrated real-time fringe order calculation for rapid depth information retrieval.

Conclusions:

• The developed system offers high-speed, long-range 2D measurement capabilities.
• The liquid-crystal Fabry-Perot resonator effectively expands the measurement depth of low-coherence interferometry.
• This technology has potential applications in fields requiring precise depth and surface analysis.