Micro-optically fabricated artificial apposition compound eye

Abstract

An artificial apposition compound eye manufactured by micro-optics technology is demonstrated. The overall thickness of the imaging system is only 320 μm, the field of view is 21° on diagonal, the F/# is 2.6. The monolithic device consists of a microlens array on a thin silica-substrate with a pinhole array in a metal layer on the backside. The image formation can be explained by the moiré-effect or static sampling. The master structures for the microlens arrays are manufactured by lithographic patterning of photo-resist and a subsequent reflow process. These master structures are replicated by moulding into UV-curing polymer. The pitch of the pinholes differs from the lens array pitch to enable an individual viewing angle for each channel. The required precision is guaranteed by using a lithographic process also for the assembly. Thus, problems with accuracy of other attempts to develop similar systems using discrete components have been overcome. Imaging systems with different sizes of pinholes, numbers of channels and separation of the viewing direction of the channels are realized and tested. A method to generate nontransparent walls between the optical channels for prevention of crosstalk is proposed. Theoretical limitations of resolution and sensitivity are discussed. Imaged test patterns are presented and measurements of the angular sensitivity function are compared to calculations using commercial raytracing software. The resolution achievable with the fabricated artificial compound eye is analyzed.