Fabrication of micro-optical structures by applying negative tone hybrid glass materials and greyscale lithography

Direct lithographic patterning of lenslet arrays with lens sags up to 75 µm and opto-mechanical structures with thickness up to 118 µm is demonstrated, using negative tone hybrid glass materials and greyscale and binary photomasks. The hybrid glass material features a maximum extinction coefficient of 2.0×10−4 µm−1 between 450 and 1600 nm, a refractive index of 1.531 at 632.8 nm and an estimated Abbe number of 45. The patterned structures exhibit rms surface roughness between 10 to 45 nm.