Method of forming a lighting system

A method of forming an extractor optical element having extraction features, comprising:

• providing a substrate material having an upper surface having an array of grooves formed thereon;
• filling the grooves with a polymer;
• defining the polymer using a patterned radiation and etching process;
• electroforming the substrate material to form a replica of the patterned upper surface with selected portions of the grooves, where the sides of the grooves can have an angle of at least 45 degrees to the plane of the upper surface;
• and
• removing the substrate from the electroform.