Characterization of a traceable profiler instrument for areal roughness measurement

Abstract

A two-dimensional profiler instrument was designed and realized at the PTB (Physikalisch-Technische Bundesanstalt). The main function of the instrument is to provide traceable results in the field of roughness measurement. It is equipped with a linear moving stylus which is guided by precision air bearings. The moving part of the stylus has weight around 1 g and is carried by a magnetic field. The contacting force of the tip onto the surface under test is controlled by a small voice coil actuator in a closed control loop. Vertical movements of the stylus are captured by two different, completely independent measurement systems, covering a range of 100 µm. The first one is an interferometer, which provides a traceable signal, and the second one is an inductive measurement system. The signal from the inductive measurement system is calibrated by the interferometer. The sample under test is carried within the x–y-plane by a linear guided table with low noise air bearings. These air bearings are preloaded by vacuum and a constant gap is achieved by gas pressure controllers. Both axes of the table are driven by linear voice coil actuators and their movement in the plane is measured by linear encoders. The sample carrier is equipped with two axes tilt compensation, by which the sample under test can be levelled automatically using the measurement system of the stylus. Real-time data acquisition, manual handling and automated procedures are managed by a programmable controller and proprietary software written in LabVIEW. After measurement, data from the system can be directly transferred into the smd- or sdf-format. Results of measurements on different samples to characterize the metrological behaviour of the instrument will be reported. To characterize the uncertainty of the instrument, a model is applied, which is in accordance with approved rules for contact stylus instruments.

Calibration and verification of areal surface texture measuring instruments

“…NPL and PTB have both developed primary stylus instruments, which use xy air-bearing slideways to move the object being measured, have laser interferometers which monitor the motion of the slideways, and use probes with air-bearing motion control and electromagnetic stylus force control [113,175]. Fig.…”

A Novel Measurement Standard for Surface Roughness on Involute Gears

“…It is traced back to the SI functioning as the reference profilometer. The HRTS is capable of providing roughness measurements with measurement uncertainties (MU) in the Nanometer range [25]. The HRTS profiler moves a stylus with diamond tip along a straight line.…”

Determination of the transfer function for optical surface topography measuring instruments—a review

“…since convolution with an infinite uniform function has no functional dependence and can be dropped. A common misconception is that whilst equations (22) and (23) express the image of a point object, equations (13) and (15) do not represent the sum of the intensity scattered from each point on an object for a coherent system. This issue will be further discussed in the following section.…”

“…Firstly, primary instrumentation that can measure areal surface topography is needed. A number of national measurement institutes (including the National Physical Laboratory (NPL) in the UK) have developed stylus instruments with displacement measuring laser interferometers that can determine the position of the stylus tip [14,15]. Knowledge of the laser source wavelength in the interferometers assures traceability to the definition of the metre.…”