| Surface relief refractive microlens arrays are designed and fabricated using two methods. In the first method lithographically patterned circular cylinders of photoresist are melted to form the spherical lens shape. In the second method the lens shapes are sculpted lithographically from photoresist using a variable transmission (grey-scale) mask made from high-energy-beam-sensitive (HEBS) glass.; The microlenses were characterised interferometrically. It was found that close to diffraction limited performance was achieved in the f/0.9 to f/2 range using the photoresist melting process, whereas diffraction limited performance was achieved using the grey-scale method in the f/1 to f/7 range using aspherical elements.; The grey-scale method was also used to fabricate a 64 level computer generated hologram of the logo of the Institut national d'optique (INO) in a single step. |
