The focusing properties of partially coherent Bessel–Gaussian beams passing through a high-numerical-aperture objective are studied based on vectorial Debye theory. Expressions for the intensity distribution, degree of coherence , and degree of polarization P are derived near the focus. Numerical calculations are performed to analyze the influences of varying corresponding parameters on the intensity distribution, , and P in the focal region. It is shown that the intensity, , and P in the focal region are all influenced by varying the effective coherent length of incident beams and maximal angle α determined by the numerical aperture of the objective. Also, the linearly polarized incident field is found to be depolarized after it is focused by a high-numerical-aperture objective.
© 2008 Optical Society of America
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