Projection of arbitrary far-field patterns using tailored microlens apertures

Usual micro-optical multi-aperture projectors image an absorbing slide-mask array buried in a tandem microlens array (MLA). The slide array fill-factor limits transmission. Additionally, realization of such devices involves precise alignment of three micro-optical layers. We propose a maskless approach by tailoring the entrance microlens apertures into simple primitives and arranging them in space-filling arrays. The entrance microlens apertures are then projected to infinity and superposed to the intended overall image. For simple symmetric final patterns, the primitive is identical to intended shape. Complex far-field patterns are generated by optically ‘jigsawing’ the primitives’ far-fields. This is done by introducing decentered lenslet segments at either or both sides of the MLA. The lens arrays have been mastered using grayscale photolithography and replicated as polymer-on-glass elements. Residual regions of the entrance lenslet array are covered by refractive diffusor structures, to scatter away incoming light. This leads to lenslets with ‘transmissive-diffusive’ apertures. We present realized maskless projectors together with preliminary characterization results.