Miniaturized, focusing fan-out elements: design, fabrication and characterization

Abstract

Abstract.We present miniaturized, focusing fan-out elements. The new micro-optical elements were fabricated using different technologies: double-sided injection moulding in polycarbonate, double-sided photolithography with subsequent transfer in quartz and direct laser writing in photoresist. The fan-out elements were characterized by measuring their efficiency and uniformity, the surface profiles of the microlenses were measured with a Twyman-Green interferometer. The overall performance of the combined, hybrid elements is demonstrated with intensity distributions recorded in the focal planes.

Focus

“…Schilling et al presented different concepts for the realization of fan-out elements. 27 In one case, the fan-out grating was actually formed directly on top of a photoresist microlens by first spincoating a second layer of resist over the lens and then directly writing the grating pattern into this layer. It was possible to generate a 5 3 5 spot pattern in an area measuring only 200 mm by 200 mm, using a lens with a diameter of 990 mm and grating period of 51.2 mm.…”

Holographically recorded gratings on microlenses for a miniaturized spectrometer array

“…[3][4][5] For planoconvex microlenses, the diffractive elements can be realized on the planar as well as on the curved surface of large arrays. 6 We have fabricated refractive microlens arrays with the diffraction grating on the curved surface of the array, which combines focusing and dispersion essentially on one transmitting surface. The advantage of such an element lies in the reduction of the total number of optical surfaces within any optical system.…”

Replicated arrays of hybrid elements for application in a low-cost micro-spectrometer array

“…Micro-optics combined with replication technologies provide obvious solutions particularly for parallel processing with array systems [1]. Hybrid (refractive/diå ractive) elements [2,3] oå er the possibility to combine two functions in one element, and are therefore suitable for the application in miniaturized spectrometer systems [4]. Refractive microlenses with a diå raction grating on the curved surface combine the focusing and the dispersion necessary for any demultiplexing system essentially on one transmitting surface.…”