Absolute distance measurement with extended range and rate based on frequency scanning interferometry with a...

Area of Science:

• Optical Metrology
• Precision Engineering

Background:

• Conventional frequency scanning interferometry (FSI) faces bandwidth limitations for high-speed, long-range distance measurements.
• Existing FSI systems often require high acquisition rates and complex active switching mechanisms.

Purpose of the Study:

• To introduce a novel FSI system integrated with a passive Fabry-Pérot (FP) delay line.
• To overcome bandwidth limitations in high-speed, long-range distance metrology.
• To enable precise range estimation using low-bandwidth detectors and signal processing.

Main Methods:

• The system utilizes multiple optical delays within a single FP cavity to generate a comb of modulation frequencies.
• A dual-cavity configuration resolves delay order ambiguity.
• A swept VCSEL laser with a 100 kHz repetition rate and 100 nm bandwidth was employed.

Main Results:

• Demonstrated absolute range measurements up to 1.4 meters with sub-3 ppm precision.
• Achieved a maximum sampling rate over 67 times lower than conventional FSI systems for the same range and repetition rate.
• Showcased a significant reduction in computational effort compared to traditional FSI.

Conclusions:

• The developed FSI system effectively overcomes bandwidth limitations for distance metrology.
• The system offers a cost-effective, compact, and scalable solution for dynamic industrial environments.
• It is compatible with standard fiber components, paving the way for real-time metrology applications.