Design of two-dimensional zero reference codes with a genetic algorithm

In mask-alignment systems a reference signal is needed to align the mask with the silicon wafers. The optical reference signal is the autocorrelation of two two-dimensional (2D) codes with binary transmittance. For a long time, one-dimensional codes have been used in grating-measurement systems to o...

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Bibliographic Details
Published in:Optics letters 2006-06, Vol.31 (11), p.1648-1650
Main Authors: SAEZ-LANDETE, José, SALCEDO-SANZ, Sancho, ZURERA, Manuel Rosa, ALONSO, José, BERNABEU, Eusebio
Format: Article
Language:English
Subjects:
Exact sciences and technology
Fundamental areas of phenomenology (including applications)
Gratings
Measurements common to several branches of physics and astronomy
Metrology, measurements and laboratory procedures
Optical elements, devices, and systems
Optics
Physics
Spatial dimensions (e.g.: position, lengths, volume, angles, displacements, including nanometer-scale displacements)
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Summary:In mask-alignment systems a reference signal is needed to align the mask with the silicon wafers. The optical reference signal is the autocorrelation of two two-dimensional (2D) codes with binary transmittance. For a long time, one-dimensional codes have been used in grating-measurement systems to obtain a reference signal. The design of this type of code has needed a great computational effort, which limits the size of the code to about 100 elements. Recently, we have applied genetic algorithms to design codes with arbitrary length. We propose the application of these algorithms to design 2D codes to generate 2D optical signals used in mask-alignment systems.
ISSN:0146-9592
1539-4794
DOI:10.1364/OL.31.001648