Simple method to determine linearity deviations of topography measuring instruments with a large range axial scanning system

Abstract

The use of areal characterization of surface texture with high accuracy in a quality control process requires reliability. Therefore, regular inspection of the measurement systems is needed. Important metrological features of a measurement system in dimensional metrology are the amplification factor and linearity. This paper presents a simple method for characterizing the axial scanning system of areal topography measuring instruments with little expense and effort, well suited for industrial routine calibration in the field. The method is based on employing a single material measure with a range of step heights. It is shown that the amplification factor and linearity deviations can be determined and adjusted for large axial measurement ranges.

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

“…Hence, for the measurements performed here the impact of sensor drift was considered negligible on the calibration measurement. The calibration dataset was formed following an existing method [15]; this reduces the need for accurate positioning stages, creating an absolute scale through self comparison against a single calibrated material measure as shown in the following procedure:…”

“…The calibration of sensor operating characteristics should be completed at regular intervals as determined by the measurement context, hence such a calibration regime should be efficient, robust, inexpensive and simple to implement. The literature has shown that such a regime can potentially be achieved through the use of multiple step heights [14] and across a user defined measurement volume [15]. However, the introduction of an additional scanning axis into the calibration procedure increases the impact of the mechanical system on the measurement and increases the time required for calibration.…”

“…The work presented here investigates the calibration of a spectral domain fibre deployed LCI sensor via three distinct methodologies: the use of a laser interferometer (Renishaw XL-80) as a traceable reference versus the creation of an absolute scale reference through the use of calibrated reference materials, either a step height or a glass coverslip. We demonstrate the use of slip gauges to create a step height calibrated by measurement on a Bruker NPFLEX, a reference scale is created using the calibrated step as a traceable two point measurement at discrete locations across the operating range of the LCI sensor [15]. We also demonstrate the use of a glass coverslip as a reference material, taking advantage of LCI tomographic measurement ability, removing the requirement for a lateral scanning procedure as required with the step height.…”

Why you should pay attention to international standards in optical metrology

“…The measured groove depth using the standardized procedure is largely independent of noise and optical effects near the edges. The definition was taken as a basis for extension to 3D topographies by extending the line segments to areas in the calibration standard ISO 25178-700 6.7.4., based on research reported in the scientific literature [13,14].…”

Metrological characteristics for the calibration of surface topography measuring instruments: a review

“…A relatively simple procedure to determine the amplification coefficient and linearity deviation for long z-axis range instruments has been recently reported and will likely be included in ISO 25178 part 700 [56]. The procedure employs a material measure containing a number of step heights (positive or negative) and stitches together segments of the response function.…”