Surface Profile Height Research Articles

Measurement of Transparent Film Using Vertical Scanning White-Light Interferometry

White-light interferometry has a good performance to measure opaque surface profile and step height; While a transparent film is measured, because two beam of lights came from transparent film surface and substrate interfere with the reference light, interference fringe appears twice at the same point and two coherence-peaks be found in the correlogram. The location algorithm of single coherence peak is computed near the maximal intensity and do not judge which interference fringe is come from film surface, so it is not sure to extract the film surface and to know the thickness of film. In this paper, the characteristic of correlogram came from transparent film is utilized to analyze the peak separation algorithms of envelope, and these algorithms are compared through results. Theoretical analysis and experiment result show that the surface and thickness of transparent film measured by white-light interference microscope have high precision when the two coherence peaks at film surface and film substrate are efficiently separated by separation algorithms.

Improved sol-gel thin film for fabrication of multilevel structures using a high-energy beam-sensitive gray-scale mask

A new photosensitive negative-tone inorganic-organic hybrid SiO 2 /TiO 2 glass with improved linear UV response property is investigated for fabrication of multilevel structures. The UV response of the sol-gel material is studied as a function of optical densities (ODs) of a high-energy beam-sensitive (HEBS) gray-scale mask. It is shown that the sol-gel material exhibits a good linear response to the OD values, which is ultimately used to define the surface profile height for a specific design. The linearity is especially useful for fabrication of diffractive optical elements with linear phase distributions. As an example, we apply the sol-gel process and the gray-scale mask to the fabrication of a blazed grating.

Frequency analyses of a signal of IR radiation from the cutting front and surface profile height in laser cutting of austenitic stainless steel

Efficient control of laser cutting processes is closely related to knowledge of heat effects in the cutting front and its surroundings. Similar to other machining processes using high power densities, in laser cutting processes it is very important to monitor the heating phenomena in the specimen material due to heat input. The processes in the laser cutting front were monitored in three ways, i.e., by a voltage signal of infrared (IR) radiation from the cutting front by measuring surface profiles of laser cuts, and by macrographs of laser cut surfaces. In the paper it is shown that an analysis of macrographs showing surface-profile corrugation of the laser cut at austenitic stainless steel as well as at low-carbon steel can be used to confirm and analyse thermal phenomena in the cutting front. A comparison is given between the power spectra of the voltage signal of the IR radiation and those of the surface-corrugation profile for different steel grades, different specimen thicknesses, and various input e...

Autocorrelation Function and Roughness Spectrum of a Growing Film Surface

AbstractRecently we developed a method that allows to derive a height-height autocorrelation function (ACF) for a randomly rough surface of a thin – film growing by the 3D island mechanism. In this paper, the ACF and roughness spectrum for several versions of the island growth model deduced by this method are presented and discussed. In the model dimension d=1+1 the ACFs are deduced in exact analytical form, and for d=2+1 the ACF' s are calculated numerically. In both model dimensions for the rms roughness the universal analytical expression connecting its with physical deposition parameters is derived. The impact of the growth hillock shape and the hillock space distribution are studied. It is shown that the ACF form is determined by the hillock space distribution and in the cases of an ideally random Poisson distribution and slightly ordered distribution the ACF is nearly gaussian although the surface profile height distribution is non-gaussian. The rms roughness is strongly dependent on the hillock shape while the autocorrelation length is determined by the hillock number density. The theoretical predictions are compared with published TEM and STM-data and the scaling behaviour of the rms roughness is analysed.

Modification of a surface profile's height parameters during strip drawing

Tactile profilometry is used to quantify surface damage resulting from single-pass strip drawing of deep-drawing-quality steel sheets. Roughness and asymmetry parameters are followed as a function of normal load. Damage is shown to correspond essentially to a truncation of the surface asperities with only minor changes for the valleys. A simple method is presented to allow the penetration depth of the dies into the surface profile to be quantified. A formula relating the skewness S k and the asymmetry ratio R vm / R pm is derived. It is shown that these parameters can be used to classify steel sheets with respect to deep drawing.

On the relationships between surface profile height parameters

It is shown that reliable estimates of the currently measured “general” surface profile height parameters can be made given a knowledge of the r.m.s. roughness, skewness and kurtosis of the profile since these three statistical parameters collectively define the distribution of surface heights to an adequate degree. “Extreme value” parameters (such as R t and R p ) are also discussed and it is shown that they can also be estimated if information about the correlation structure of the profile is available.

Rms skew and kurtosis of surface profile height distributions: some aspects of sample variation

The unit of scale of a surface profile height distribution may be described by its rms value. To describe the shape of that distribution the use of its moment coefficients of skewness and kurtosis has been proposed. This paper discusses the sample variation of these parameters. The effects of sampling from highly non-normal populations, such as those found with worn surfaces, and the influence of correlation between profile ordinates are considered with a view to establishing suitable sample sizes for required parameter confidence limits