Jacques Duparré

Novel optics/micro-optics for miniature imaging systems

The visual revolution triggered by the commercial application of digital image capturing devices generates the need for new miniaturized and cheap optical imaging systems and cameras. However, in imaging we can observe only a permanent miniaturization of elements but always similar optical principles are applied which are known to the optical designers for many decades. With the newly gained spectrum of technological capabilities it is the time to ask: Which vision principle should be used at which level of miniaturization and which technology has to be applied in order to achieve the perfectly adapted imaging system? In this paper we present an overview of two insect inspired artificial compound eye concepts for compact vision systems fabricated by lithographic technologies, one classical miniaturized objective and its wafer-scale fabrication and the use of variable focal length liquid lenses for miniaturized autofocus- and zoom objectives without moving parts.

Microoptical artificial compound eyes - from design to experimental verification of two different concepts

Two novel objective types on the basis of artificial compound eyes are examined. Both imaging systems are well suited for fabrication using microoptics technology due to the small required lens sags. In the apposition optics a microlens array (MLA) and a photo detector array of different pitch in its focal plane are applied. The image reconstruction is based on moire magnification. Several generations of demonstrators of this objective type are manufactured by photo lithographic processes. This includes a system with opaque walls between adjacent channels and an objective which is directly applied onto a CMOS detector array. The cluster eye approach, which is based on a mixture of superposition compound eyes and the vision system of jumping spiders, produces a regular image. Here, three microlens arrays of different pitch form arrays of Keplerian microtelescopes with tilted optical axes, including a field lens. The microlens arrays of this demonstrator are also fabricated using microoptics technology, aperture arrays are applied. Subsequently the lens arrays are stacked to the overall microoptical system on wafer scale. Both fabricated types of artificial compound eye imaging systems are experimentally characterized with respect to resolution, sensitivity and cross talk between adjacent channels. Captured images are presented.