What is an axicon (and what they can do for us)

In 1954 axicons were defined by John McLeod as rotationally symmetrical optical devices able to produce a line image lying along the axis from a point source of light. Nowadays we understood a“line image“ as a focal distribution with axial dimension significantly higher than conventional lenses do. Consequently an axicon have no definite focal point but a focal segment distribution. A typical example is a lens with a weak conical surface on one face. Before Laser devices spread, they were used for very different technical and metrological purposes as, for instance, optical alignment. On the other hand, we can combine axicons with other optical elements to confine energy inside a ring pattern. This reason caused that they were employed in corneal surgery for trephination and also refractive correction of hyperopia. Far from this last characteristic, we are more interested in the extreme depth of field that axicons can achieve to compensate accommodative lack and moderate presbyopia. The design of these elements to achieve good far, intermediate are near vision are presented. Moreover, by retinal image simulation, we have tested the performance of there elements for different eye pupil sizes. Axicons shows a good behaviour in front of other existent solutions.