Extended depth of field in an intrinsically wavefront-encoded biometric iris camera

This work describes a design process that greatly increases the depth of field of a simple three-element lens system intended for biometric iris recognition. The system is optimized to produce a point spread function that is insensitive to defocus so that recorded images may be deconvolved without the knowledge of the exact object distance. This is essentially a variation on the technique of wavefront encoding; however, the desired encoding effect is achieved by aberrations intrinsic to the lens system itself, without the need for a pupil phase mask.