Optical element for focusing approximately collimated rays

An optical element, comprising:

• a single piece, monolithic lens having a entrance face receiving a light beam, a exit face opposite the entrance face, and an optical axis;
• wherein a central portion of the exit face forms a cone about the optical axis with a lateral conical surface,
• wherein the entrance face forms a truncated cone about the optical axis,
• wherein a central portion of the entrance face directly opposite the central portion of the exit face is planar and perpendicular to the optical axis,
• wherein the cone is formed as a complementary cone to the truncated cone,
• wherein the light beam is split by an internal surface of the lateral conical surface of the cone by reflection, the light beam reflecting away from the optical axis towards a peripheral portion of the entrance face,
• wherein the peripheral portion of the entrance face reflects the split light beam internally to be parallel to the optical axis, the peripheral portion of the entrance face forming a first aspheric boundary surface,
• wherein the split light beam is then refracted by a peripheral portion of the exit face towards a focal point, the peripheral portion of the exit face being a second aspheric boundary surface.