Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Section 4, Taipei, Taiwan.
Sensors (Basel). 2011;11(11):10293-307. doi: 10.3390/s111110293. Epub 2011 Oct 31.
In order to determine light aberrations, Shack-Hartmann optical wavefront sensors make use of microlens arrays (MLA) to divide the incident light into small parts and focus them onto image planes. In this paper, we present the design and fabrication of long focal length MLA with various shapes and arrangements based on a double layer structure for optical wavefront sensing applications. A longer focal length MLA could provide high sensitivity in determining the average slope across each microlens under a given wavefront, and spatial resolution of a wavefront sensor is increased by numbers of microlenses across a detector. In order to extend focal length, we used polydimethysiloxane (PDMS) above MLA on a glass substrate. Because of small refractive index difference between PDMS and MLA interface (UV-resin), the incident light is less refracted and focused in further distance. Other specific focal lengths could also be realized by modifying the refractive index difference without changing the MLA size. Thus, the wavefront sensor could be improved with better sensitivity and higher spatial resolution.
为了确定光像差，夏克-哈特曼光学波前传感器利用微透镜阵列（MLA）将入射光分成小部分，并将它们聚焦到像平面上。在本文中，我们提出了一种基于双层结构的用于光学波前传感应用的具有各种形状和排列的长焦距 MLA 的设计和制造。长焦距 MLA 可以在给定波前下确定每个微透镜的平均斜率时提供高灵敏度，并且通过探测器上的微透镜数量增加了波前传感器的空间分辨率。为了延长焦距，我们在玻璃基板上的 MLA 上方使用了聚二甲基硅氧烷（PDMS）。由于 PDMS 和 MLA 界面（UV 树脂）之间的折射率差较小，因此入射光的折射和聚焦距离更远。通过不改变 MLA 尺寸来改变折射率差，还可以实现其他特定的焦距。因此，波前传感器可以通过提高灵敏度和更高的空间分辨率得到改善。
