High-Performance Continuous Aspheric Microlenses Array For Shack-Hartmann Sensor

Micro lens array (MLA) is the critical element for Shack-Hartmann wave front sensor. But conventional MLA based on diffractive optics shows strong chromatic aberration, which cause the MLA only works for narrow band. The broad band MLA requires continuous profile, which can not be fabricated using binary optics fabrication technique. In this presentation, we present the fabrication for continuous aspheric MLA by employing gray scale mask with one-step moving photolithography and one-step etching process. The fabricated MLA exhibits small surface roughness (rms < 5 nm), high uniformity of focal length (< 0.6%), nearly 100% filling factor and good focal spots quality approaching diffraction limit. The working wavelength shows wide band (0.45 ~ 0.7 mum), promising the MLA can be successfully employed in Shack-Hartmann systems with white light or multiple laser wavelengths.