Aspheric lens to increase the depth of focus.

For high-resolution optical systems, a long depth of focus is desirable. Unfortunately, resolution and depth of focus are inversely related. In this work, a novel lens is presented to produce long depth of focus beams, keeping the same resolution. The equations to perform the optical design of this kind of lenses and results are shown for a simple lens that can produce beams with a spot size of 2.9 μm over a range of 1.5 mm and for an achromatic doublet with a focus depth of 10 mm.