Publication: A high speed autofocusing system for micro system applications
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Issued Date
2016
Resource Type
File Type
application/pdf
ISSN
1674862X
Other identifier(s)
2-s2.0-84975789836
Rights Holder(s)
มหาวิทยาลัยศรีนครินทรวิโรฒ
Bibliographic Citation
Journal of Electronic Science and Technology. Vol 14, No.1 (2016), p.73-79
Suggested Citation
Sripolsaen P., Mittrapiyanuruk P., Keawtrakulpong P. A high speed autofocusing system for micro system applications. Journal of Electronic Science and Technology. Vol 14, No.1 (2016), p.73-79. doi:10.11989/JEST.1674-862X.510051 Retrieved from: https://hdl.handle.net/20.500.14740/5940
Author(s)
Abstract
In this paper, we present a high speed autofocus system for micro system applications and design a look-up-table based autofocusing algorithm for applications when a target object is always visible, e.g., manufacturing parts with alignment fiducials. We perform an evaluation of 24 focus measures to verify that which focus measure is the best for the look-up-table based method. From the evaluation, we find that the Chebyshev moments-based focus measure (CHEB) is the most suitable. Furthermore, we also develop a look-up-table based autofocus system that uses CHEB as the focus measure. In training phase, we offline construct a table from training images of an object that are captured at several lens distances. Each entry of table consists of focus measure computed from image and lens distance. In working phase, given an input image, the algorithm first computes the focus measure and then finds the best match focus measure from the table and looks up the corresponding lens position for moving it into the in-focus position. Our algorithm can perform autofocusing within only 2 steps of lens moving. The experiment shows that the system can perform high speed autofocusing of micro objects.