VECTORIAL PHYSICAL OPTICS MODELING OF HIGH NA LENS SYSTEM

A fully vectorial physical optics modeling of (both real and ideal) lens systems can be formulated via field tracing. The local plane interface approximation at the curved surface and the accurate free space propagation are combined smoothly. The polarization effect, which is very important for high NA focusing lenses, is fully included. An ideal lens can be modeled by a B-operator. It allows for the modelling of arbitrary beam incidence. Fig. 1 shows the tightly focused spots (magnitude shown is energy density) by an ideal lens with NA=0.95. For well-designed lenses, aberrations are minimized for perfect alignment, which is often not the case in practice. Therefore, to analyze the performance of a real lens, especially when tolerance of misalignment is of importance, is a fundamental exercise. Fig. 2 shows that the real lens performed very well with no misalignment compared with the ideal case. But it suffers from aberrations when inclined, which is agreed with the experimental results.

Pic-Vectorial Physical Optics Modeling of High NA Lens System1
Figure 1: The figures on the top row show the focal spot (energy density) when using a circular aperture on a plane wave with a wavelength of 532 nm. The figures on the bottom row show the focal spot when using an annular aperture on a plane wave with a wavelength of 532 nm. The polarization from left to right is linear, circular, radial and azimuthal, respectively. (rights at IAP)


Pic-Vectorial Physical Optics Modeling of High NA Lens System2
Figure 2: The figures on the top row show the focal spot (energy density) when using a circular aperture on a Gaussian wave polarized in the y direction with a wavelength of 632.8 nm. The figures on the bottom row show the focal spot when using an annular aperture with the same incident beam. The focal spots obtained by real and ideal lenses are compared with normal incidence. The focal spot by the real lens with inclined incidence is compared with experimental results from literature. (rights at IAP)