Synthetic-wavelength-based dual-comb interferometry for fast and precise absolute distance measurement

Abstract

We present an absolute distance measurement system using a phase-stable dual-comb system with 56.09 MHz repetition rate and 2 kHz repetition rate difference. A relative phase stability of 0.1 rad in 0.5 ms between two combs is achieved using a mutual locking scheme. The dual-comb ranging system combines the time-of-flight (TOF) method, synthetic-wavelength interferometry (SWI), and carrier wave interferometry (CWI). Each method provides a particular ambiguity range and resolution, and they can be applied simultaneously and linked to enhance the precision and measurement rate of the ranging system. The experimental results demonstrate that a precision of 1.2 μm is obtained without time averaging, and the precision can be improved to 3 nm with only 10 ms averaging time using the SWI method described in this study. The precision reaches a sub-nanometer when the averaging time exceeds 0.1 s. A system with high accuracy and short averaging time would enhance fast measurement performance in various industrial applications. The ambiguity range is about 2.67 m in our system, we test the performance of the system with 1.5 mm range at 1.5 m distance.

Absolute Measurement of the Refractive Index of Water by a Mode-Locked Laser at 518 nm

“…Assuming that the phase of the wavelength λ is φ 0 for the reference mirror, and φ 1 for the measurement mirror, the length L p can be calculated as ( φ 1 − φ 0 )/(2 π ) × λ for the wavelength λ [ 38 , 39 ]. Please note that φ 1 and φ 0 are the unwrapped phases.…”

Lazerle Uzaklık Ölçümü ve Bu Alanda Kullanılan Ölçüm Yöntemlerinin Karşılaştırılması

“…Özellikle atmosferik çalışmalarla ilgili olarak rüzgarın hızı, yönü, hava kirliliği gibi konularda bu metod oldukça başarılı olup gelişmeye açık bir yöntemdir. Ancak bununla birlikte lazerle mesafe ölçümünün daha hızlı ve daha hassas sonuçları sağlaması açısından da önem çalışmaların yapıldığı görülmektedir [9].…”

Nanometer Precision Time-Stretch Femtosecond Laser Metrology Using Phase Delay Retrieval

“…To reach higher precision, combined approach based on TOF method and coherent detection is adopted. Cross-correlation-based TOF method [6], [7], synthetic wavelength interferometry [8]- [10], spatial dispersive interferometry [11], [12], and dual comb interferometry [13]- [15] can realize nanometer precision with averaging time of several milliseconds to seconds.…”