Method of polishing a surface of a waveguide

A method of polishing a target surface of a waveguide to achieve accurate perpendicularity of the target surface relative to two non-parallel surfaces of the waveguide, the method comprising:

• providing a polishing apparatus comprising a polishing plate having a flat surface parallel to a polishing plane and defining a reference plane, and an adjustable mounting apparatus configured to hold the waveguide during polishing at any of a plurality of angular orientations relative to the reference plane;
• positioning a first optical alignment sensor configured to emit one or more collimated light beams and to receive reflections therefrom, and a first light reflecting apparatus configured to reflect a collimated light beam exactly 90 degrees, such that a first collimated light beam of the first optical alignment sensor is reflected off of a surface parallel to the reference plane, and a second collimated light beam of the first optical alignment sensor, perpendicular to the first collimated light beam, is reflected off of the first non-parallel surface;
• positioning a second optical alignment sensor configured to emit one or more collimated light beams and to receive reflections therefrom, and a second light reflecting apparatus configured to reflect a collimated light beam exactly 90 degrees, such that a first collimated light beam of the second optical alignment sensor is reflected off of a surface parallel to the reference plane, and a second collimated light beam of the second optical alignment sensor, perpendicular to the first collimated light beam of said second optical alignment sensor, is reflected off of the second non-parallel surface;
• by use of the mounting apparatus, aligning the waveguide within said polishing apparatus by adjusting the angular orientation of the waveguide such that the reflections received by the first optical alignment sensor align within said first optical alignment sensor and the reflections received by the second optical alignment sensor align within said second optical alignment sensor, thereby being indicative of perpendicularity between the reference plane and each of the first and second non-parallel surfaces;
• and
• by use of the polishing apparatus, polishing the target surface of the aligned waveguide.