Patent
Scanning interferometry with reference signal
Artur G. Olszak,Joanna Schmit +1 more
Reads0
Chats0
TLDR
In this article, a reference signal is used to track the actual behavior of the scanner (60) in an interferometer (40) to produce scanner-position data that can be used to correct errors introduced by scanner nonlinearities and other error sources.Abstract:
A reference signal is used to track the actual behavior of the scanner (60) in an interferometer (40) to produce scanner-position data that can be used to correct errors introduced by scanner nonlinearities and other error sources. A narrow-band light source (42) is advantageously utilized to cover the entire range of operation of the scanner (60). Because of the independent reference channel, the invention is suitable for implementation with all types of conventional interferometric techniques. The concept is preferably implemented by utilizing an additional light source (42) and the same scanner (60) used for the measurement, so that the OPD varies in synchronization of both the reference-signal and data-collection procedures. Alternatively, a high temporal-coherence filter (32) may be used with the same light source (12) and optical path used for the interferometric measurement.read more
Citations
More filters
Patent
Profiling complex surface structures using scanning interferometry
TL;DR: In this paper, a method including comparing information derived from a scanning interferometry signal for a first surface location of a test object to information corresponding to multiple models of the test object was proposed.
Patent
Interferometer and method for measuring characteristics of optically unresolved surface features
TL;DR: Disclosed is an interferometry analysis method that includes comparing information derivable from multiple inter-ferometry signals corresponding to different surface locations of a test object to information corresponding to multiple models of the test object, wherein the multiple models are parameterized by a series of characteristics that relate to one or more under-resolved lateral features of the object.
Patent
Interferometry method and system including spectral decomposition
TL;DR: In this paper, the authors propose a method that combines the reflected measurement light with reference light, where the measurement light and reference light are derived from a common source, and there is a non-zero optical path length difference between the measured light and the reference light that is greater than a coherence length of the measured measurement light.
Patent
Interferometry method for ellipsometry, reflectometry, and scatterometry measurements, including characterization of thin film structures
TL;DR: In this paper, a method for imaging test light emerging from a test object over a range of angles to interfere with reference light on a detector was proposed, where the test and reference light are derived from a common source.
Patent
Scanning interferometry for thin film thickness and surface measurements
TL;DR: In this paper, a method for providing a low coherence scanning interferometry data for at least one spatial location of a sample having multiple interfaces, where the data is collected using a low-coherence scanner having an illumination geometry and an illumination frequency spectrum, was proposed.
References
More filters
Journal ArticleDOI
Digital wave-front measuring interferometry: some systematic error sources.
TL;DR: To study the occurrence of wave-front irregularities caused by dust particles a model has been developed and countermeasures derived which assure sufficient regularity of contour line plots, and the repeatability of the present experimental setup was better than λ/200 within the 3σ limits.
Journal ArticleDOI
Efficient nonlinear algorithm for envelope detection in white light interferometry
TL;DR: The new algorithm is shown to be near optimal in terms of computational efficiency and can be represented as a second-order nonlinear filter and in combination with a carefully designed peak detection method the algorithm exhibits exceptionally good performance on simulated interferograms.
Journal ArticleDOI
Improved vertical-scanning interferometry
TL;DR: A method that combines phase-shifting and coherence-peak-sensing techniques to permit measurements with the height resolution ofphase-sh shifting interferometry without the interval-slope limitation of lambda/4 per data sample of phase- Shifting Interferometry is described.
Patent
Combination of white-light scanning and phase-shifting interferometry for surface profile measurements
Chiayu Ai,Paul J. Caber +1 more
TL;DR: In this article, the authors proposed a technique that combines white-light VSI and single-wavelength PSI capabilities to improve the accuracy of height measurements in steep regions and in areas with large inter-pixel steps on the test surface.
Patent
Method and apparatus for optical interferometric measurements with reduced sensitivity to vibration
TL;DR: In this paper, a phase shifter was used to change the phase difference between the beams in the interferometer while data from both cameras (10,11) was taken by a frame grabber and saved in a computer.