Dot distribution type of grayscale mask and colorscale photomask for fabrication diffractive and refractive microlens arrays
The fundamental relations of the ultraviolet (UV) light transmittance of the soft polymer film filled by a large number of basic micro-pattern-structures composed of micro-squares, are acquired experimentally. The polymer films with different distribution density of basic color-micro-pattern-structure in the visible range, are also constructed easily, so as to perform single photomask photolithography for fabrication microlenses with very fine surface profile. The patterned polymer films demonstrate a modulated UV-light penetrating property. Models for describing the penetrating behaviors of UV-light over polymer films covered by a large number of basic grayscale or colorscale micro-patternstructures constructed, for instance, typical micro-square and other micro-pattern-structures shaped by partially overlapping several micro-squares, are set up. Several key factors, which influence the penetrating behavior of UV-light, and then the surface character, and also the quality of correspondent functioned micro-structures in photoresist and further substrate, such as diffractive or refractive microlens, are discussed carefully. The UV-light transmitting measurements demonstrate a desired UV-light intensity variance trend, which is basically consistent with theoretical prediction.