Microlenses and their Applications in Microcameras

The use of microcameras has increased significantly in a variety of applications in many fields including medical, automotive, surveillance, and astronomy. This miniaturized imaging system, while introducing innovative applications also introduced several limitations in imaging at the microscale. Among those limitations are limited field of view and limited maneuverability. One approach to overcome these limitations is to utilize the versatility of microlenses as an integral part of the microcamera.;Here, possible solutions to the microcamera's limited maneuverability and limited field of view are introduced by employing microlenses in different techniques. A multiple viewpoint imaging microcamera is introduced to address the issue of maneuverability. The microcamera is based on lightfield photography and provides the capability of multiple viewpoints from a single image capture. The microcamera includes a microlens array fabricated using the conventional method of photoresist thermal reflow. The design, fabrication, and testing of the microcamera are discussed.;A novel microlens fabrication process is also introduced. This fabrication process can be used to produce optical devices with a large field of view. The microlenses utilize the natural shrinkage of hydrogels to produce the microlens mold. Polydimethylsiloxane (PDMS) is employed as the final microlens material. The design, fabrication, and testing of microlenses are discussed. A compound eye based on the fabrication process above is also introduced. The fabrication and capabilities of the compound eye are discussed.;In addition, bio-inspired PDMS microlens arrays on curved surfaces are also introduced. The microlens arrays are connected by thin PDMS bridge-like structures. When placed on a curved surface, most of the stress will be localized on the bridge structure and not the microlens arrays. The design, fabrication and testing of the microlenses are discussed. The stress on the microlens arrays and bridge structure is also simulated and analyzed.;Furthermore, a flexible camera array inspired by both apposition compound eyes and mammalian eyes is also introduced. The cameras are connected by a very flexible polymer allowing for instantaneous reconfigurability to achieve a wide field of view. Images from each camera can be stitched providing a panoramic view. The fabrication and assembly of the camera array are discussed.