From Light to Displacement: A Design Framework for Optimising Spectral-Domain Low-Coherence Interferometric Sensors for In Situ Measurement

Abstract

Growing requirements for in situ metrology during manufacturing have led to an increased interest in optical coherence tomography (OCT) configurations of low coherence interferometry (LCI) for industrial domains. This paper investigates the optimisation of spectral domain OCT hardware and signal processing for such implementations. A collation of the underlying theory of OCT configured LCI systems from disparate sources linking the journey of the light reflected from the object surface to the definition of the measurand is presented. This is portrayed in an applicable, comprehensible design framework through its application to profilometry measurements for optimising system performance.

Pragmatic Micrometre to Millimetre Calibration Using Multiple Methods for Low-Coherence Interferometer in Embedded Metrology Applications

“…A fibre clamp was used to hold the end of the single-mode fibre (780HP with FC/PC connector) perpendicular to the object target. The theory and data processing behind the LCI sensor measurements are covered in previous works [2,4]. To perform scanning measurements, a set of 3-axis stepper motor driven translation stages (MFA-PPD, Newport) in an XYZ configuration were used.…”

“…Implementation of in-situ dimensional sensing into the machining environment has been historically difficult due to the hostile operating conditions. However, low coherence interferometry (LCI) is a proven measurement technique that has shown promise for operating in dynamic environments, with a small footprint due to straight forward integration into fibre optic systems and has been shown to effectively work in various media [2][3][4].…”

Special Issue on Manufacturing Metrology

“…It achieved a Z-directional measurement range of approximately 46 µm as well as a measurement resolution of 20 nm [13]. For the purpose of in situ measurement, a design framework for optimizing spectral-domain low-coherence interferometric sensors was proposed for profilometry measurements to optimize system performance [14]. Another in situ measurement system dealing with the on-machine precision form truing of resin-bonded spherical diamond wheels was also proposed [15].…”

Thermo-Optical Measurements and Simulation in a Fibre-Optic Circuit Using an Extrinsic Fabry–Pérot Interferometer under Pulsed Laser Heating

“…Accordingly, there is a demand for the development of methods for the remote control of thermal processes by fibre-optic means [7][8][9]. By configuring low-coherence interferometry with fibre optics, sensors can be miniaturised and placed at some distance from the electronics [7,12]. Chemically inert, compact and durable optical fibre integrated in the process of production is affordable due to the relatively inexpensive optical components.…”