@PhdThesis{dbt_mods_00008655,
  author = 	{Horvath, Balazs},
  title = 	{Entwicklung einer optischen Messmethode zur Analyse lateraler Mikrostrukturoberfl{\"a}chen},
  year = 	{2007},
  month = 	{Aug},
  day = 	{02},
  keywords = 	{Mikrostruktur; Oberfl{\"a}chenanalyse; Rauhigkeit; Laser Speckle; microstructure; surface analysis; roughness},
  abstract = 	{Abstract
The study describes an optical, coherent, parametrical technique for non-contact 
inspection of sidewalls of microstructures. The method is based on coherent 
scattering and evaluation of objective speckle patterns. The vertical areas are 
illuminated by a convergent laser beam and the reflected characteristic 
intensity structures are detected directly over the incident beam in a space 
range as wide as possible. It is typical of the speckle phenomenon that its 
spatial frequency is inversely related to the diameter of the incident beam. 
Thus, the primary reflection (measurement signal) and the secondary scattered 
disturbance are to be separated by means of a spatial band-pass filter. 
Roughness parameters of vertical areas can be derived from speckle-contrast, 
cross and auto-correlation models.
Experimentally determined characteristic curves of the speckle-contrast 
measurements follow the theoretical relation and its practical use can be 
extended up to an RMS roughness of 0.2-0.25 {\textmu}m. A new spatial correlation 
evaluation is proposed, in which the correlation-coefficient is calculated by a 
minor shift of the probe. It is demonstrated that the incident angle variation 
or the probe shift exert influence upon the gradient of characteristic curves. 
Thus, the application range and the precision of the measurement can be varied 
and the process can be adjusted to certain requirements. By means of the 
measurement models, vertical surfaces of micro-form tools or microstructures can 
be analysed in the range of RMS=0..0.5 {\textmu}m with a precision of 8-10 nm.
For analysis of the reliability, a likelihood-method is derived which allows for 
both systematic and statistical errors in order to calculate the confidence 
intervals.
In the last part of the study, a simulation software is developed on the basis 
of Kirchhoff's diffraction theory, by which the functions of speckle measurement 
methods can be modelized for optional illuminations, material properties and 
geometrical arrangements. Thus, a computative possibility is made available for 
the examination of technical feasibility of any speckle evaluations.},
  url = 	{https://www.db-thueringen.de/receive/dbt_mods_00008655},
  url = 	{http://uri.gbv.de/document/gvk:ppn:550647643},
  file = 	{:https://www.db-thueringen.de/servlets/MCRZipServlet/dbt_derivate_00012127:TYPE},
  language = 	{de}
}