Paradigm shifts in surface metrology. Part II. The current shift

Abstract

This is the second part of the paper 'Paradigm shifts in surface metrology'. In part I, the three historical paradigm shifts in surface metrology were brought together, and the subsequent evolution resulting from the shifts discussed. The historical philosophy highlighted the fact that the paradigm shifts must be robust and flexible, meaning that surface metrology must allow for full control of surface manufacture and provide an understanding of the surface functional performance. Part II presents the current paradigm shift as a 'stepping stone', building on the above historical context. Aspects of surface geometry will also have to cater for surfaces derived from disruptive application, i.e. structured and freeform surfaces are identified candidates. The current shift is presented in three aspects: from profile to areal characterization; from stochastic to structured surfaces; and from simple geometries to complex freeform geometries, all spanning the millimetre to sub-nanometre scales. In this paradigm shift, the scale of surface texture is beginning to approach some of the geometrical features in micro/nano electro-mechanical systems devices and is becoming one of the most important functionality indicators. Part II will contextualize the current shifts in the discipline of surface metrology, and cement surface metrology in place in the ultra precision and nanotechnology age.

Multi-scale freeform surface texture filtering using a mesh relaxation scheme

“…The concept of scale-limited surfaces was introduced by Jiang et al for areal surface texture [5,11,43]. Scale-limited surfaces provides a flexible way to identify various different scales of surface texture.…”

“…Many research papers and industrial standards have been published describing the measurement and characterisation of such simple surfaces [4][5][6][7][8][9][10][11]. However, with the development of science and technology, more and more complex surfaces are being produced which, unlike the conventional surfaces, have no axes of rotation and no translational symmetry and could have any shape or design; such complex surfaces have been termed "freeform surfaces".…”

“…Measuring and characterising ordinary simple surfaces such as planes, spheres and cylinders is mature and has been intensively studied and developed [1][2][3][4][5][6]. Many research papers and industrial standards have been published describing the measurement and characterisation of such simple surfaces [4][5][6][7][8][9][10][11].…”

Intelligent sampling for the measurement of structured surfaces

“…Traditional surface geometry descriptors and the traditional statistical parameters such as Sa, Sq or Ssk [37] have been reported to have a lack of efficiency when used to characterize structured surfaces [4]. In a new feature-based characterisation system [17,38], surfaces are treated as a composition of diverse geometric features.…”

“…Uniform sampling is widely accepted as the most natural sampling method due to its good numerical operability and the maturity of its theoretical foundations [1,2]. However, the emergence of structured surfaces [3,4] has forced surface metrologists to consider the drawbacks of uniform sampling. The main drawbacks include coherent spectral aliasing [5] (see figure 1) and a lack of efficiency in terms of measuring time and data storage [6].…”