Filtering Out Contrast Reversals for Microscopy Autofocus
Applied Optics, Vol. 38, Issue 4, pp. 638-646 (1999)
http://dx.doi.org/10.1364/AO.38.000638
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Abstract
Autofocus functions based on measurement of image resolution appear to be precise and robust for biological microscopy. However, the through-focus response of these functions previously exhibited unwanted local maxima, or side peaks. Here we report theoretical and experimental studies showing that side peaks are mainly a result of contrast reversals inherent in optical systems at mid-range frequencies. These contrast reversals are not present in frequencies near optical cutoff. Contrast reversals thus limit the lower cutoff for resolution measurement filters, whereas signal-to-noise limits the upper cutoff. These improved bandpass design criteria led to sharp, unimodal autofocus responses for all tested microscopy specimens.
© 1999 Optical Society of America
OCIS Codes
(070.2590) Fourier optics and signal processing : ABCD transforms
(110.4850) Imaging systems : Optical transfer functions
(170.5810) Medical optics and biotechnology : Scanning microscopy
Citation
Michael A. Oliva, Miguel Bravo-Zanoguera, and Jeffrey H. Price, "Filtering Out Contrast Reversals for Microscopy Autofocus," Appl. Opt. 38, 638-646 (1999)
http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-38-4-638
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