Preshaping photoresist for refractive microlens fabrication

Refractive microlenses are fabricated by the preshaped photoresist refractive optics by melting (P²ROM) process. A polar coordinate HeCd laser beam lithography system (laser writer) is used to directly expose a continuous spheroidal profile into photoresist to fabricate 200-μm-diam microlenses with speeds between f/1.5 and f/5. Interferometric surlace measurements, used to determine the optical quality of the preshaped microlenses, indicate reduced spherical aberration in slow lenses fabricated by the P²ROM method.