Abstract: A gradient-index lens for directing incident electromagnetic radiation comprises at least one substrate having a plurality of micro-features (e.g., trenches or holes) that may be arranged in a pattern of varied size and/or spacing. Each of the micro-features has at least one dimension that is less than a wavelength of the electromagnetic radiation. The spacing between adjacent micro-features is less than the wavelength of the electromagnetic radiation, and the size and spacing of the micro-features are sufficient to produce an effective refractive index profile of the lens that is graded. A thermal imaging device incorporating a gradient-index lens is also provided.

Abstract: A gradient-index lens for focusing incident electromagnetic radiation comprises at least first and second substrates. Each of the substrates has a plurality of trenches or holes formed therein. The first substrate is stacked on the second substrate such that trenches or holes in the first substrate are substantially aligned with corresponding trenches or holes in the second substrate to form combined trenches or holes. Each of the combined trenches or holes has a width or diameter that is less than a wavelength of the electromagnetic radiation, and the spacing between adjacent ones of the combined trenches or holes is less than the wavelength of the electromagnetic radiation. The size and spacing of the combined trenches or holes in the stacked substrates are sufficient to produce an effective refractive index profile of the lens element that is graded. A method for producing the lens is also provided.