Inverse fringe projection can be seen as an improvement to the classical fringe projection method to significantly speed
up the measurement of geometry defects of optical cooperative workpieces requiring no hardware changes to the
classical setup. The CAD model of an ideal specimen is used in a virtual fringe projection system to generate a single
sophisticated inverse fringe projection pattern which is, then, projected onto the surface of the real workpiece.
Subsequently, 3D-geometry defects can be extracted directly and very quickly from a single image captured by the real
camera using elaborate 2D-algorithms. This allows for verification of allowed geometry tolerances with a significantly
reduced latency time.
KEYWORDS: Sensors, Signal detection, Scanning electron microscopy, Electron microscopes, Optical spheres, Reconstruction algorithms, Mathematical modeling, Finite element methods, Scintillators, Absorption
Due to the emerging degree of miniaturization in microstructures, Scanning-Electron-Microscopes (SEM) have become
important instruments in the quality assurance of chip manufacturing. With a two- or multiple detector system for
secondary electrons, a SEM can be used for the reconstruction of three dimensional surface profiles. Although there are
several projects dealing with the reconstruction of three dimensional surfaces using electron microscopes with multiple
Everhart-Thornley detectors (ETD), there is no profound knowledge of the behaviour of emitted electrons. Hence,
several values, which are used for reconstruction algorithms, such as the photometric method, are only estimates; for
instance, the exact collection efficiency of the ETD, which is still unknown. This paper deals with the simulation of
electron trajectories in a one-, two- and four-detector system with varying working distances and varying grid currents.
For each detector, the collection efficiency is determined by taking the working distance and grid current into account.
Based on the gathered information, a new collection grid, which provides a homogenous emission signal for each
detector of a multiple detector system, is developed. Finally, the results of the preceding tests are utilized for a
reconstruction of a three dimensional surface using the photometric method with a non-lambert intensity distribution.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.