Rapid fabrication of thermoplastic polymer refractive microlens array using contactless hot embossing technology

Abstract

A thermoplastic polymer refractive microlens array has been rapidly fabricated by contactless hot embossing technology through the stainless steel template with micro through-holes array, which has a diameter of 150 µm and a pitch of 185 µm. By optimizing the technical parameters including heating and demoulding temperature, loading pressure, loading and pressure holding time, a series of high quality microlenses arrays of different sags could be obtained. In addition, the sag and the radius of curvature of the microlens are controllable. The geometrical and optical properties of the microlenses are measured and the influence of temperature and pressure duration on the optical properties of the microlenses are analysed. The results show good surface features and optical performances. Unlike previous contactless hot embossing, a low cost and durable stainless steel template was utilized instead of silicon or nickel mold to avoid valuable equipments and complicated fabrication procedure. Besides, the whole contactless hot embossing process was absence of vacuum equipment. We think that the technology could be an attractive high flexibility method for enhancing efficiency and reducing cost.

A novel thermal reflow method for the fabrication of microlenses with an ultrahigh focal number

“…[1][2][3][4][5][6][7][8] The geometry of the microlens will be different for different application purposes. [1][2][3][4][5][6][7][8] The geometry of the microlens will be different for different application purposes.…”

Fabrication and Characterization of Curved Compound Eyes Based on Multifocal Microlenses

“…However, there are concerns about the volume loss during the photoresist melting process, the surface profile quality of the molds [ 36 ], and the consistency of microdroplets when printing a dense array one by one. Contactless hot embossing is considered to be a versatile one-step technique to prepare MLAs regardless of the quality of the molds’ inner relief, applied in mass production of microlens arrays [ 37 , 38 ], and the radius of the curvature can also be precisely controlled by process parameters. This method demonstrates the potential of making microlenses with multiple focal lengths.…”

Microlens arrays with adjustable aspect ratio fabricated by electrowetting and their application to correlated color temperature tunable light-emitting diodes

“…The increasing demand for micro-optoelectronic devices has prompted the development of MLA fabrication methods including direct laser writing [24][25][26], reactive ion etching [27,28], cylindrical micropillars photoresist reflow [29][30][31], hot embossing [32][33][34] and inkjet printing [35,36]. Direct laser writing enables fabrication of MLA with different shapes.…”