Design, fabrication, and testing of a Shack–Hartmann sensor with an automatic registration feature

Abstract

In this research, design, construction, and testing of an innovative Shack–Hartmann sensor are described. As the most critical component, a polymer microlens array is injection molded and mounted on a board-level CMOS camera such that the focal plane of the microlens array is on the camera’s image plane. To allow for automatic registration of the spots of the measured area, a diffusing surface was created at the center of the lens array in the same diamond machining process in an uninterrupted operation. This unique diffusing surface does not generate an image spot. The no-spot feature functions as the reference in the measurement on the camera’s image plane. Using this unique feature, large global tip-tilt error can be detected and eliminated. In this research, both experiments and simulation have shown that the Shack–Hartmann sensor built using low cost components is capable of precision wavefront detection. This research also demonstrated that automatic registration based on the diffusing surface is simple and reliable.

Fabrication of spherical microlens array by combining lapping on silicon wafer and rapid surface molding

“…For the mold surface, the R a value is ~10 nm, which is considered to be adequate for most optical and photonics applications. To investigate the surface roughness change from mold to polymer, the surface roughness of a random microlens among the arrays was measured and is listed in table 4. This shows that the R a value for the mold surface before and after coating and the polymer surface has not experienced significant changes, indicating that the graphene coating process and molding process have not changed the surface roughness.…”

“…The microlens array is an important optical component that enables the miniaturization of photonics systems and imaging and sensing assemblies, and also enhances the integration of multi-functional optical devices [1][2][3][4]. For this purpose, different types of microlens arrays with various aperture sizes and pitches have been investigated, including Alvarez lens arrays [5], PDMS-based lenses [6][7][8], liquid lenses [9,10], fluidic lenses [11][12][13][14][15][16] and three-dimensional (3D) microlens arrays [17].…”