High-precision absolute distance and vibration measurement with frequency scanned interferometry

Abstract

In this paper, we report high-precision absolute distance and vibration measurements performed with frequency scanned interferometry using a pair of single-mode optical fibers. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. A high-finesse Fabry-Perot interferometer(F-P) was used to determine frequency changes during scanning. Two multiple-distance-measurement analysis techniques were developed to improve distance precision and to extract the amplitude and frequency of vibrations. Under laboratory conditions, measurement precision of ∼ 50 nm was achieved for absolute distances ranging from 0.1 meters to 0.7 meters by using the first multiple-distance-measurement technique. The second analysis technique has the capability to measure vibration frequencies ranging from 0.1 Hz to 100 Hz with amplitude as small as a few nanometers, without a priori knowledge.

High-precision absolute coordinate measurement using frequency scanned interferometry

“…Here we report frequency scanned interferometry (FSI) measurements carried out as part of an R&D program aimed at aligning the tracking system and embedded accelerator components of the proposed Si detector [4]. These measurements follow previously reported FSI work [1,2].…”

“…In order to ensure transverse misalignments of tracking elements to better than 10 m [8], we aim at longitudinal line-of-sight distance accuracies of 1 m or better. Previous work demonstrated such precision for single-laser, single-channel distance measurements under highly controlled conditions [1] and for dual-laser, single-channel distance measurements under poorly controlled environmental conditions [2].…”

“…The FSI method was pioneered for high-energy detector alignment by the Oxford ATLAS group [5][6][7]. More detail on the principles of the FSI method and on the FSI analysis techniques used here can be found in [1], along with a discussion of systematic uncertainties in single-laser, single-channel distance measurements. Discussion of the advantages of a dual-laser FSI method used here and a summary of measurements can be found in [2], but we focus here on consistency checks of a single-laser configuration in a closed, stable environment.…”

“…We reported previously on measurements of absolute distance with the FSI method [1,2]. Absolute position is determined by several related absolute distances measured simultaneously.…”

Dimensional Metrology and Frequency Sweeping Interferometry

“…The most important are based only upon a tunable laser and a frequency measurement sub-system, systems built around both a reference and a measurement interferometer, or based on the use of an additional stabilized laser, some developed for high accuracy under special controlled laboratory conditions, others driven by robustness in uncontrolled environments (Kinder & Salewski, 2002;Cabral & Rebordão, 2005;Swinkels et al, 2005;Yang et al, 2005). An example is the Dual FSI concept, conceived to overcome the decrease in accuracy as the measurement range increases, as a consequence of the uncertainty propagation in the synthetic wavelength measurement.…”