A graduated microlens array is presented in this paper. The proposed device has the same aperture microlens with a gradually increasing sag in the substrate. The design produces gradual decrease in the focal length and intensity when the light passes through the graduated microlens array. This paper presents a new graduated microlens array fabrication method that uses a variable printing gap in the UV lithography process. This method can precisely control the geometric profile of each microlens array without using the thermal reflow process. The angles between the mask and photoresist were placed at 5°, 8°, 10°, 15°, and 20° using a fixture designed in this study. The mask patterns were ellipses with an isosceles triangle arrangement to compensate for the partial geometry.
Microlens array UV proximity printing Gradual sag height Micro-optics
This work was supported by the National Science Council (series no. NSC92-2212-E-005-005) of Taiwan, R.O.C. Thanks are due to G. Marso Electronics Inc. (GME) for their cell phone panel module knowledge input to generate research interests.