At SMA, we have been designing telecentric lenses for more than a decade. Most often a hybrid lens (a lens that incorporates both glass and molded plastic aspheric elements) provides excellent control of aberrations while providing the telecentricity required.
A telecentric lens is one in which the Chief Ray from each of the object points in the field strikes the imaging surface perpendicular to the sensor. This is becoming increasingly important as smaller sensor pixels are each covered with a micro lens on the imager surface to enhance their sensitivity. A secondary advantage of a telecentric lens is that refocusing does not change the field of view at all.