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.
|Number of pages||5|
|Journal||Journal of the Optical Society of America A: Optics and Image Science, and Vision|
|Publication status||Published - 1 Jun 2016|
- Optics at surfaces
- Fourier optics and signal processing
- Diffraction theory
- Electromagnetic optics