Fabrication of ZnSe Microlens Array for a Wide Infrared Spectral Region

The infrared (IR) is a strategically important band for numerous applications from environment to biochemical imaging. Here a novel IR optical component integrates more than 2000 plano-concave microlenses on the zinc selenide (ZnSe) surface within a footprint of 5×5mm
²
is proposed by a combined method of femtosecond laser direct irradiation and chemical wet etching. Microlenses with diameter from 15 to 30 μm are realized by controlling the laser power and etching time. The uniform close-packed microlens arrays (MLAs) with minimized volume and high transparency at wavelengths of 0.76~22μm are realized. The MLAs have relatively good topography and surface quality. The modulation transfer function (MTF), imaging test and optical-focusing test confirm the outstanding IR imaging. Owing to the merits of micro-size, light weight, high integration and excellent IR imaging performance, the as-fabricated MLA is promising in cutting-edge mid-IR and far-IR application, such as IR sensing system, imaging system, and so on.