Micro-optical artificial compound eyes

Abstract

Natural compound eyes combine small eye volumes with a large field of view at the cost of comparatively low spatial resolution. For small invertebrates such as flies or moths, compound eyes are the perfectly adapted solution to obtaining sufficient visual information about their environment without overloading their brains with the necessary image processing. However, to date little effort has been made to adopt this principle in optics. Classical imaging always had its archetype in natural single aperture eyes which, for example, human vision is based on. But a high-resolution image is not always required. Often the focus is on very compact, robust and cheap vision systems. The main question is consequently: what is the better approach for extremely miniaturized imaging systems—just scaling of classical lens designs or being inspired by alternative imaging principles evolved by nature in the case of small insects? In this paper, it is shown that such optical systems can be achieved using state-of-the-art micro-optics technology. This enables the generation of highly precise and uniform microlens arrays and their accurate alignment to the subsequent optics-, spacing- and optoelectronics structures. The results are thin, simple and monolithic imaging devices with a high accuracy of photolithography. Two different artificial compound eye concepts for compact vision systems have been investigated in detail: the artificial apposition compound eye and the cluster eye. Novel optical design methods and characterization tools were developed to allow the layout and experimental testing of the planar micro-optical imaging systems, which were fabricated for the first time by micro-optics technology. The artificial apposition compound eye can be considered as a simple imaging optical sensor while the cluster eye is capable of becoming a valid alternative to classical bulk objectives but is much more complex than the first system.

Wafer-Level Hybrid Integration of Complex Micro-Optical Modules

“…Multi-aperture imaging concepts implementing microlens arrays are currently investigated to be used as the optics of compact vision sensors for automotive, machine vision, or measurement applications [28]. A main technological difficulty in all multi-aperture systems is the fabrication of features, which serve as channel isolation in order to suppress scattering and optical cross talk which would lead to ghost images.…”

Region-of-Interest Estimation for Adaptive Resource Allocation in Multi-Aperture Imaging Systems

“…Such methods would be used within an adaptive procedure to allocate additional imaging resources within the multi-aperture optical system. A straightforward implementation of GillesD saliency model to region-of-interest estimation is the entropy map (1) where is the normalized intensity histogram taken in a region about pixel in the image. As an example, an aerial image of an airport is shown in Fig.…”

“…In these systems, multi-aperture optical imaging systems built using state-of-the-art microoptics technology are used for data collection [1] , and multiple low-resolution images are combined using signal processing techniques to produce a "nal image with both a high angular resolution and a large "eld-of-view. Because the systems use small aperture lenses, the depth-of-"eld of such devices is increased over traditional imaging systems, mitigating the need for adjustible lens focus.…”

Design strategies to simplify and miniaturize imaging systems

“…We can quote, for example, systems involving curved detectors [1], multichannel systems inspired by the compound eyes of insects [2][3][4][5][6][7], multichannel systems based on the TOMBO principle [8], lenseless imagery [9][10][11][12][13][14][15][16][17], and folded imaging systems [18,19]. Therefore, choosing the suitable system for a given application among all these concepts is often not obvious for an optical designer.…”