We find that a microcylindrical axilens with a closed boundary and with an <i>f</i>-number less than 1 still can achieve the properties of long focal depth and high transverse resolution, unlike a microcylindrical axilens with an open boundary, which fails to maintain those properties for low <i>f</i>-numbers. The focusing characteristics of the closed-boundary axilens and the open-boundary axilens are numerically investigated based on the boundary integral method. The numerical results show that the ratio of the extended focal depth of the closed-boundary axilens to the focal depth of the conventional microlens can reach up to 1.26 and 2.12 for the preset focal depths 3 and 5 μm, respectively, even though the <i>f</i>-number is reduced to 1/3.
© 2002 Optical Society of America
(050.0050) Diffraction and gratings : Diffraction and gratings
(050.1970) Diffraction and gratings : Diffractive optics
(220.0220) Optical design and fabrication : Optical design and fabrication
Jia-Sheng Ye, Bi-Zhen Dong, Ben-Yuan Gu, Guo-Zhen Yang, and Shu-Tian Liu, "Analysis of a closed-boundary axilens with long focal depth and high transverse resolution based on rigorous electromagnetic theory," J. Opt. Soc. Am. A 19, 2030-2035 (2002)