Insect-Mimetic Imaging System Based on a Microlens Array Fabricated by a Patterned-Layer Integrating Soft Lithography Process

Fabrication of a light screen-aperture integrated flexible thin film micro-lens array for a biomimetic superposition compound eye

Micro-lens array, an artificial compound eye vision system, provides a wide field of view and multi-perspective view. However, it has not been adopted as a computer vision application due to its limited visible range and high optical interference. In this research, a novel fabrication method for the flexible polydimethylsiloxane micro-lens array with a polytetrafluoroethylene light screen-aperture integrated layer was established by the simple protrusion method. The integrated layer provided longer visible range by one meter while maintaining the wide field-of-view of 100 °. The resulting images were used for obtaining depth information of a target as an example and for analyzing the rectangular and hexagonal arrangements of the micro-lenses for the future applications. With the improved visual range, wide field-of-view and flexibility, the fabricated micro-lens array can be applied to the small and curved CMOS image sensors in the future.

Low-cost, thermoplastic micro-lens array with a carbon black light screen for bio-mimetic vision

Micro-lens array is a great example of bio-mimetic technology which was inspired by compound eyes found in insects and is used in lasers, optical communication, and 3D imaging. In this study, a micro-lens array was fabricated from cyclic olefin copolymer using a cost-effective method: compression molding and thermal reflow. Also, a light screen was installed between lenses to reduce the optical interference for clearer individual images. Cyclic olefin copolymer-based micro-lens array showed good optical results under a standard optical microscope. By placing the fabricated micro-lens array directly on an image sensor, it was observed that the light screen shows significant improvement in image quality. Also, the point spread function was analyzed to confirm the optical performance and the effectiveness of the micro-lens array with the light screen installed.

Artificial Compound Eye Systems and Their Application: A Review

The natural compound eye system has many outstanding properties, such as a more compact size, wider-angle view, better capacity to detect moving objects, and higher sensitivity to light intensity, compared to that of a single-aperture vision system. Thanks to the development of micro- and nano-fabrication techniques, many artificial compound eye imaging systems have been studied and fabricated to inherit fascinating optical features of the natural compound eye. This paper provides a review of artificial compound eye imaging systems. This review begins by introducing the principle of the natural compound eye, and then, the analysis of two types of artificial compound eye systems. We equally present the applications of the artificial compound eye imaging systems. Finally, we suggest our outlooks about the artificial compound eye imaging system.

Depth-of-Field-Extended Plenoptic Camera Based on Tunable Multi-Focus Liquid-Crystal Microlens Array

Plenoptic cameras have received a wide range of research interest because it can record the 4D plenoptic function or radiance including the radiation power and ray direction. One of its important applications is digital refocusing, which can obtain 2D images focused at different depths. To achieve digital refocusing in a wide range, a large depth of field (DOF) is needed, but there are fundamental optical limitations to this. In this paper, we proposed a plenoptic camera with an extended DOF by integrating a main lens, a tunable multi-focus liquid-crystal microlens array (TMF-LCMLA), and a complementary metal oxide semiconductor (CMOS) sensor together. The TMF-LCMLA was fabricated by traditional photolithography and standard microelectronic techniques, and its optical characteristics including interference patterns, focal lengths, and point spread functions (PSFs) were experimentally analyzed. Experiments demonstrated that the proposed plenoptic camera has a wider range of digital refocusing compared to the plenoptic camera based on a conventional liquid-crystal microlens array (LCMLA) with only one corresponding focal length at a certain voltage, which is equivalent to the extension of DOF. In addition, it also has a 2D/3D switchable function, which is not available with conventional plenoptic cameras.