MICRO METROLOGY | ARTICLE
Part 1 2 3 4 5 6
Title Areal surface texture drawing indications
Terms, definitions and surface texture parameters Specification operators Comparison rules
Verification operators Classification of methods for measuring surface texture
70 Measurement standards for areal surface texture measurement instruments 71 72
Software measurement standards Software measurement standards – XML file format
600 601 602 603 604 605 606 607 700 701
Nominal characteristics of areal surface topography instruments Nominal characteristics of contact (stylus) instruments
Nominal characteristics of non-contact (confocal chromatic probe) instruments
Nominal characteristics of non-contact (phase shifting interferometric microscopy) instruments Nominal characteristics of non-contact (coherence scanning interferometry) instruments Nominal characteristics of non-contact (point autofocus) instruments Nominal characteristics of non-contact (variable focus) instruments Nominal characteristics of non-contact (imaging confocal) instruments Calibration of areal surface measuring instruments
Calibration and measurement standards for contact (stylus) instruments
Status Date CD PS PS
NS NS PS
FDIS PS
CD
WD PS PS PS PS
FDIS CD
WD WD PS
2013 2012 2012 - -
2010 2013 2013 2013 2013 2010 2010 2013 2013 2012 2013 2013 2013 2010
<< Table 1: Current status of ISO 25178 areal specification standards. Key: WD – working draft, CD – committee draft, NS – not started, DIS – draft international standard, FDIS – final draft international standard, PS – published standards. >>
which can be used to calibrate commercial instruments. Before discussing the transfer artefacts, it is advantageous to look at the current state of play with international specification standards for areal surface topography. In 2002, ISO technical committee 213 formed working group (WG) 16 to address standardisation of areal surface texture measurement methods. WG 16 is developing a number of draft standards encompassing definitions of terms and parameters, calibration methods, file formats and characteristics of instruments. Several of these standards have now been published and a number are at various stages in the review and approval process (readers are encouraged to comment on the public drafts). All the areal standards are part of ISO 25178, which will consist of at least the parts shown in table 1 (correct at the time of writing), under the general title Geometrical product specification (GPS) — Surface texture: Areal.
Only the standards relating to calibration will be discussed here. Part 70 of ISO 25178 describes the artefacts that are used to calibrate areal surface topography measuring instruments and includes the profile calibration artefacts from ISO 5436 part 1 (2000), but with new names. There are four part 60X standards that have been published: part 601 (stylus instruments), part 602 (confocal chromatic probes), part 603 (phase stepping interferometers) and part 604 (CSI). At the time of writing, parts 605, 606 and 607 are drafts at the working stage. The 60X standards currently contain common terminology, metrological characteristics (see below) and a
list of parameters that can influence the uncertainties when using the instrument. The standards also contain technical annexes that discuss the theory and operation of the instruments. However, as the 60X series developed, it was realised that there are a large number of sections in the various parts of the 60X series that are common to all instruments based on a microscope objective. For example, research has shown that a common set of metrological characteristics can be found that does not differ for each instrument type. Therefore, a new standard is under development (part 600), which will cover all the common aspects. Once part 600 is published, the 60X series will be withdrawn and re-issued with the common sections removed. Part 701 is concerned with the calibration of stylus instruments. Part 700, which is still under development, will cover the calibration of surface topography measuring instruments and is expected to be common across all instruments types. Once part 700 is published, part 701 will be withdrawn.
The philosophy being developed by the ISO committee to deal with the calibration of areal instruments is as follows. The calibration process for a surface topography measuring instrument should involve the determination of the characteristics of the scales of the instrument, and a determination of the instrument’s spatial frequency response, i.e. how the instrument will respond to complex surface features. Often the latter part of this process is overlooked and an instrument is considered ‘calibrated’ if only the characteristics of the scales have been determined. With this
22 | commercial micro manufacturing international Vol 7 No.1
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