scope:

The present guideline VDI/VDE 2655 Part 1.1 applies to interference microscopes used for measuring the topography of industrial surfaces. The calibration procedures described are comparable to the methods which have already proved themselves in the guidelines dealing with the traceability of contact stylus instruments (see Figure 1) (DKD-R 4-2; EAL-G20). Accordingly, the standards examined there (optical flat, optical grating, depth measurement standard, roughness measurement standard) have also been used where this is possible.

The present part of the guideline series is confined to the basic calibration of the interference microscope. This includes traceability to the unit of length via measurement at traceable depth measurement standards. This corresponds to the right-hand vertical path in Figure 1. From these measurement procedures comes the derivation for calculating the measurement uncertainty in the instrument calibration and the derivation for measurement at depth measurement standards.

The corresponding procedures for surface roughness parameters will be described in VDI/VDE 2655 Part 2.1.

Application of this guideline pursues the following aims:

• Improved comparability of surface measurements using different microscopes as well as between microscopes and contact stylus instruments with the standards (documents) and the standards for contact stylus instruments

• Definition of conditions for traceability to the unit of length as shown in Figure 1

• Determination of suitability for calibration and definition of the scope of validity of a calibration

Definition of minimum requirements for the calibration process and for acceptance conditions

• Provision of a GUM-conforming model for calculating the measurement uncertainty of the measuring method using an interference microscope

• Definition of the requirements for a report of results