Optical EngineeringEfficient f/1 binary-optics microlenses in fused silica designed using vector diffraction theory
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The diffraction efficiencies of binary-optics lenses with low f/#'s deviate from predictions of scalar diffraction theory. To increase the diffraction efficiencies for low f/#'s, vector diffraction theory is necessary. In this paper, we describe the design and fabrication of a 30 x 50 array of f/1 binary-optics microlenses using direct-write electron-beam lithography and reactive-ion etching. The diameter of each lens is 160 μm, and the focal length is 165 μm. The center-to-center spacing between the lenses is 300 μm, and they are fabricated in fused silica. The measured diffraction efficiency for an elliptical Gaussian beam is 80% for lenses designed using vector diffraction theory and 63% for lenses designed using scalar diffraction theory.