Optical implementation of cubic-phase distribution lenses for passive infrared motion sensors

A cubic-phase distribution is applied in the design and fabrication of inexpensive lenses for passive infrared motion sensors. The resulting lenses produce a point spread function (PSF) capable to distinguish the presence of humans from pets by the employment of the so-called wavefront coding method. The cubic phase distribution used in the design can also reduce the optical aberrations present on the system. This aberration control allows a low tolerance in the fabrication of the lenses and in the alignment errors of the sensor. The lens was manufactured on amorphous hydrogenated carbon thin film, by employing well-known micro fabrication process steps. The optical results demonstrates that the optical power falling onto the detector surface is attenuated for targets that present a mass that is horizontally distributed in space (e.g. pets) while the optical power is enhanced for targets that present a mass vertically distributed in space (e.g. humans).