High-speed range and velocity measurement using frequency scanning interferometry with adaptive delay lines...

Area of Science:

• Optical Metrology
• Interferometry
• Laser Technology

Background:

• Accurate measurement of target range, displacement, and velocity is crucial in various scientific and industrial applications.
• Traditional interferometry methods face challenges in achieving high resolution and broad measurement ranges.

Purpose of the Study:

• To develop and demonstrate a frequency scanning interferometer for high-resolution, wide-range measurement of target motion.
• To improve measurement accuracy and reduce modulation frequencies using an adaptive delay line.

Main Methods:

• Utilized a frequency scanning interferometer with a vertical-cavity surface-emitting laser (100 nm tuning range, 100,000 scans/s).
• Incorporated an adaptive delay line in the reference beam to reduce modulation frequencies to sub-gigahertz levels.
• Determined range, displacement, and velocity from the interference signal's phase, with fine alignment from a reference interferometer.

Main Results:

• Achieved sub-nanometer displacement resolution.
• Demonstrated sub-100-nm range resolution.
• Obtained velocity resolution of 12µms⁻¹ over a 300 mm depth measurement range.

Conclusions:

• The developed frequency scanning interferometer offers high precision for measuring target motion.
• The adaptive delay line effectively reduces modulation frequencies, enhancing system performance.
• This technology has potential applications in precision engineering, scientific research, and industrial inspection.