Non-contact measurement technique for dimensional metrology using optical comb

• Experiments on absolute-length measurement for dimensional applications have been conducted using an optical-comb pulsed interferometer.
• The measurement accuracy mainly involves the quality of the envelope interference fringes, which is influenced by air-flow fluctuations and mechanical vibrations.
• The proposed technique can provide sufficient accuracy for non-contact measurement in applications.

This paper proposes a non-contact pulsed interferometer for dimensional metrology using the repetition frequency of an optical frequency comb. A compact absolute-length measuring system is established for practical non-contact measurement based on a single-mode fiber interferometer. The stability and accuracy of the measurements are compared with those from a commercial incremental laser interferometer. The drifts of both systems have the same tendency and a maximum difference is approximately 0.1 μm. Subsequently, preliminary absolute-length measurements up to 1.5 m were measured. The signal-to-noise ratios of the small signals are improved by a frequency-selective amplifier. It is apparent that the noise is rejected, and the intensity of the interference fringes is amplified, achieving a maximum standard deviation of measurement approximately 1 μm. The proposed technique can provide sufficient accuracy for non-contact measurement in applications such as a simple laser-pulse tracking system.