A hybrid microlens/aperture mask assembly is fabricated, aligned and mounted on a CCD imager for an application in an imaging polarimeter. The microlens array is produced by direct laser writing in photoresist followed by electroforming and replication onto a glass substrate in registration with a slit aperture array on the reverse side. An alignment of the combined arrays to the CCD imager of better than 0.7 μm in lateral position and 0.005 deg rotation is achieved. Stray light of less than 1% was measured for the hybrid module. The optical microsystem satisfied the challenging requirements of the imaging polarimeter and the technique has applications in other areas of optical sensing, metrology and processing. © 1997 Society of Photo-Optical Instrumentation Engineers.