Method For Fabrication Of Microlens Arrays Research Articles

Novel fabrication method of microlens arrays with High OLED outcoupling efficiency

We presented a novel fabrication method of pyramidal and hemispherical polymethylmethacrylate (PMMA) microlens arrays to improve the outcoupling efficiency. Pyramidal microlens arrays were fabricated by replica molding processes using concave-pyramidal silicon molds prepared by the wet etching method. Concave-hemispherical PMMA thin film was used as a template for fabrication of the hemispherical microlens array. The concave-hemispherical PMMA template was prepared by blowing a N2 gas stream onto the thin PMMA film suspended on a silicon pedestal. A PMMA microlens arrays with hemispherical structure were fabricated by a replica molding process. The outcoupling efficiency of the hemispherical microlens array was greater than that of the pyramidal microlens array. The outcoupling efficiency of hemispherical microlens arrays with a higher contact angle was larger than that of those with lower contact angle. This indicates that, for the hemispherical microlens with larger contact angle, more light can be extracted from the OLEDs due to the decrease in the incident angle of the light at the interface between an air and a hemispherical microlens arrays. After attaching a hemispherical microlens array with contact angle of 50.4° onto the OLEDs, the luminance was enhanced by approximately 117%.

Fabrication of high numerical aperture micro-lens array based on drop-on-demand generating of water-based molds

Abstract This letter presented a simple fabrication method of micro-lens arrays with high numerical aperture based on a new drop-on-demand generating of water-based mold. The micro-droplet array which acted as the water-based mold was generated on the polypropylene substrate using a drop-on-demand generator, and then a replication process was followed for fabricating the micro-lens arrays with high numerical aperture. A spherical-like micro-lens array with the numerical aperture of 0.62 was fabricated. The surface of the formed micro-lens was demonstrated super smooth (Ra~0.5 nm, Rq~0.7 nm, Rmax~13.2 nm, 2×2 μm2 scanned area) by the atomic force microscope, which can reduce the optical noise. The qualities of imaging and light gathering characteristics of the MLAs were evaluated by the optical microscope.