1. A camera, comprising: a first substrate having first and second opposing surfaces, the first and second surfaces having first and second planar regions in a periphery thereof; a convex refractive element on one of the first and second surfaces of the first substrate; a second substrate having third and fourth opposing surfaces, the third and fourth surfaces having third and fourth planar regions in a periphery thereof; a concave refractive element on one of the third and fourth surfaces of the second substrate; a separation between the first to second substrates, the separation including an air gap between the convex refractive element and the concave refractive element; a third substrate having fifth and sixth opposing surfaces, the fifth and sixth surfaces having fifth and sixth planar regions in a periphery thereof; and a detector array on the third substrate, the concave refractive element being closer to the detector array than the convex refractive element, the first to third substrates being stacked along a z-axis, wherein the z axis is perpendicular to a plane of the detector array, and secured along the z-axis at respective opposing planar regions.