title: Focused fields of given power with maximum longitudinal electric field component inside a substrate.
abstract: Closed formulas are presented for the electromagnetic field of given power in the lens pupil, which maximizes the longitudinal electric field when focusing through an interface at arbitrary depth along the optical axis. The optimum pupil field is found to be a continuous, monotonously increasing function of the radial pupil coordinate, which differs considerably from the commonly used annular illumination. Several cases of pupil fields and focused fields are shown for different materials, NA, and focusing depth. Also, the effect of absorbing media is considered.
authors.forename: Q Y
authors.initials: QY
authors.lastname: van den Berg
authors.forename: S F
authors.initials: SF
authors.lastname: Pereira
authors.forename: H P
authors.initials: HP
authors.lastname: Urbach