Fabrication of frequency-selective surfaces using microlens projection photolithography

This letter describes the use of microlens projection photolithography (μLPL) for the fabrication of repetitive metallic micropatterns, and the application of these patterns as frequency-selective surfaces. Microlens projection photolithography uses an array of microlenses (diameter $\text{d=1–1000}$ micrometers) to project an array of images of an illuminated mask into photoresist. We converted these arrays into patterns in metals by electron beam evaporation and lift off. This technique can produce arrays over areas $\text{>10\hspace{0.17em}}{\mathrm{cm}}^2$ with submicrometer feature sizes in a single exposure. We fabricated arrays of metallic micropatterns on substrates transparent to infrared radiation, and demonstrated that appropriate patterns acted as frequency-selective filters.