Dispersion turning point enhanced Fizeau interferometer for micro-displacement sensing.

Area of Science:

• Optical Metrology
• Interferometry
• Precision Measurement

Background:

• Fizeau interferometers offer robustness and stability but suffer from decaying sensitivity with increased cavity length in micro-displacement detection.
• Existing Fizeau interferometer designs face limitations in sensitivity for precise micro-displacement measurements as cavity length increases.

Purpose of the Study:

• To enhance the sensitivity of Fizeau interferometers for micro-displacement detection.
• To develop a Fizeau interferometer with improved and adjustable sensitivity and dynamic range.

Main Methods:

• Proposed a dispersion turning point (DTP) enhanced Fizeau interferometer utilizing a quartz plate as a beam splitter.
• Achieved DTP by adjusting the cavity length between the beam splitter's reflective coating and the test surface.
• Leveraged the zero-dispersion point of quartz for sensitivity attenuation when deviating from DTP.

Main Results:

• Realized ultra-high sensitivity to micro-displacement when operating near the DTP.
• Achieved a high constant sensitivity of 0.333 nm/nm over a 56 nm wavelength range.
• Demonstrated adjustable dynamic range by tuning the DTP position.

Conclusions:

• The DTP-enhanced Fizeau interferometer significantly improves sensitivity for micro-displacement detection.
• The proposed method provides a stable, polarization-independent, and tunable solution for high-precision measurements.
• This enhanced Fizeau interferometer offers a versatile platform for various micro-displacement sensing applications.