Stylus contact method

In contact methods, a sharp object is contacted with the sample and the variation in height position of this stylus is recorded as it is scans the jc- and/or y-directions of the surface. Contact methods are available both for 2D and three-dimensional (3D) measurements. From a 3D z x, y) map it is possible to calculate all relevant topography measures. However, since the method relies on the contact between the surface and a sharp object... 

One of two basic principles is employed in most commercial optical non-contact methods. The first is the laser-focusing technique, which works according to the same basic principle as a CD-player, and can best be described as an optical equivalent of the stylus... 

The contact profilometer consists of a fine stylus that is drawn across the surface and is supposed to follow the contours. Optical profilometers do not involve contact with the surface. In some instruments, a very small spot from a bright light source is focussed on the surface. As the spot is moved across the surface, a servo system alters the height of the source so as to maintain a sharp focus. Various types of optical profilometer are discussed by Whitehouse" and by Bennett, and are compared with contact methods. 

ISO 3274 1996 Geometrical Product Specifications (GPS) — Surface texture Profile method — Nominal characteristics of contact stylus instruments. 

DIN EN ISO 3274 1998-04 (1998) Geometrical product specification (GPS). Surface texture Profile method Nominal characteristics of contact (stylus) instruments. 

A variation of the LORIA test uses new technology to evaluate the surface quality of Class A automotive body panels, eliminating subjective visual methods. It uses a low-intensity visible laser to detect surface deviations and imperfections. The beam is projected and scanned across the area, reflected on screen and captured by a high-resolution video camera. There is no contact with the surface, no stylus and no damage. 

The most common mechanical method of estimating curvature involves a stylus which scans the surface along the radial direction by making physical contact with it. The resulting record of the out-of-plane displacement w(r) versus distance r from some reference point is converted to the radius of curvature p, or curvature k, using the relation... 

As the name suggests, this method records the crater depth by scanning a stylus over the surface of the substrate analyzed, i.e. in much the same way that contact mode AFM is carried out (AFM is covered in Appendix A. 11.4). Stylus profilometry is applied in contact mode after the removal of the sample from the SIMS instrument. Although stylus profilometry only provides a line scan, it is capable of a depth resolution precision approaching 1 nm. An example of a typical stylus profilometry scan output is portrayed along with a top-down image of the three craters measured in Figure 5.24. Note Only one crater would typically be measured at a time. 

In past years, a contacting-stylus instrument similar to a phonograph needle has been the standard method for surface-profile measurements. A fine diamond stylus coupled to a transducer scans the surface, providing closely spaced profiles that can be displayed on an x-y recorder. The elevation sensitivity is excellent but unfortunately the stylus sometimes obliterates the original surface features. The diameter of the stylus point determines the width and depth of the crevices it will measure. Table 2 compares the vertical and horizontal resolving powers of several microtopography techniques. The other electron techniques mentioned in Table 2 will be discussed in later sections. 

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