A monolithic multi-focal length miniature refractive element comprising a first surface region and a second surface region. The first surface region has a first characteristic radius of curvature. The second surface region has a second radius of curvature that is different from the first characteristic radius of curvature. The first and second surface regions are formed on a single optical element blank. The optical element blank can be a composite of two or more materials.

 
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< Imaging optical system

< Projection lens and projection image display apparatus

> Methods to make diffractive optical elements

> Fresnel lens sheet, process of producing Fresnel lens sheet, mold for use in the production process, and rear projection screen comprising the Fresnel lens sheet

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