Optical system for producing a structured beam

The optical system of claim wherein the focusing element comprises at least one of:

• a focusing lens;
• a ball lens;
• or
• a spherical mirror.

An optical alignment system comprising:

• a convex ball lens comprising a spherical entry surface for imparting aberrations in an illuminating beam, the convex ball lens comprising a material having a refractive index of greater than 1.8;
• an electromagnetic radiation source configured to provide a substantially coherent beam of electromagnetic radiation,
• wherein the electromagnetic radiation source is arranged to produce the illuminating beam for illuminating the convex ball lens over a selected illumination fraction of the spherical entry surface and with a corresponding selected focus of the illuminating beam,
• wherein the selected illumination fraction is selected, at least in part, on the corresponding selected focus of the illuminating beam and the refractive index of the material of the convex ball lens, causing the illuminating beam to traverse a sufficient refractive volume of the convex ball lens to impart aberrations in the illuminating beam emerging from the convex ball lens such that the illuminating beam comprises a structured optical beam;
• and
• a focusing element arranged along an optical axis of the optical alignment system;
• wherein the aberrations imparted in the illuminating beam comprise spherical aberrations created by the convex ball lens, wherein the spherical aberrations create, at least in part, the structured optical beam;
• one or more objects to be aligned;
• and
• a detector for detecting a position of an object relative to the structured optical beam.

A method of producing a structured optical beam, the method comprising:

• providing a convex ball lens having a spherical entry surface, the convex ball lens comprising a material having a refractive index of greater than 1.8;
• providing an electromagnetic radiation source configured to provide a substantially coherent beam of electromagnetic radiation;
• providing a focusing element arranged along an optical axis;
• and
• arranging the electromagnetic radiation source so as to provide an illuminating beam which illuminates the convex ball lens over a selected illumination fraction of the spherical entry surface and with a corresponding selected focus of the illuminating beam,
• wherein the selected illumination fraction is selected, at least in part, on a selected focus of the illuminating beam and the refractive index of the material of the convex ball lens, causing the illuminating beam to traverse a sufficient refractive volume of the convex ball lens to produce aberrations in the illuminating beam emerging from the convex ball lens such that the illuminating beam comprises a structured optical beam,
• wherein the plurality of aberrations imparted in the illuminating beam comprises spherical aberrations created by the convex ball lens, wherein the spherical aberrations create, at least in part, the structured optical beam.