Optical detector system with multiple path lengths

A system comprising:

• a first lens that directs incoming light onto a first surface of a polarized beam splitter (PBS);
• the PBS that directs:
• a first portion of the incoming light having a first polarization from the first surface of the PBS to a detector array, wherein a first path of the first portion of the incoming light from the first lens to the detector array has a first length, and
• a second portion of the incoming light having a second polarization through the first surface of the PBS to a first quarter wave retarder (QWR);
• the first QWR that:
• changes a polarization of the second portion of the incoming light from the second polarization to a first intermediate polarization, and
• directs the second portion of the incoming light having the first intermediate polarization to a convex mirror;
• the convex mirror that reflects the second portion of the incoming light having the first intermediate polarization back to the first QWR;
• the first QWR that:
• changes a polarization of the second portion of the incoming light from the first intermediate polarization to the first polarization, and
• directs the second portion of the incoming light having the first polarization onto a second surface of the PBS;
• the PBS that directs the second portion of the incoming light having the first polarization from the second surface of the PBS to a second QWR;
• the second QWR that:
• changes a polarization of the second portion of the incoming light from the first polarization to a second intermediate polarization, and
• directs the second portion of the incoming light having the second intermediate polarization to a flat mirror;
• the flat mirror that reflects the second portion of the incoming light having the second intermediate polarization back to the second QWR;
• the second QWR that:
• changes a polarization of the second portion of the incoming light from the second intermediate polarization to the second polarization, and
• directs the second portion of the incoming light having the second polarization onto the second surface of the PBS;
• the PBS that directs the second portion of the incoming light having the second polarization through the second surface of the PBS onto the detector array, wherein a second path of the second portion of the incoming light from the first lens to the detector array has a second length that is greater than the first length;
• and
• the detector array comprising a plurality of photodetectors.

A method comprising:

• directing, using a first lens, incoming light onto a first surface of a polarized beam splitter (PBS);
• directing, using the PBS:
• a first portion of the incoming light having a first polarization from the first surface of the PBS to a detector array, wherein a first path of the first portion of the incoming light from the first lens to the detector array has a first length, and
• a second portion of the incoming light having a second polarization through the first surface of the PBS to a first quarter wave retarder (QWR);
• changing, at the first QWR, a polarization of the second portion of the incoming light from the second polarization to a first intermediate polarization;
• directing, using the first QWR, the second portion of the incoming light having the first intermediate polarization to a convex mirror;
• reflecting, at the convex mirror, the second portion of the incoming light having the first intermediate polarization back to the first QWR;
• changing, at the first QWR, a polarization of the second portion of the incoming light from the first intermediate polarization to the first polarization;
• directing, using the first QWR, the second portion of the incoming light having the first polarization onto a second surface of the PBS;
• directing, using the PBS, the second portion of the incoming light having the first polarization from the second surface of the PBS to a second QWR;
• changing, at the second QWR, a polarization of the second portion of the incoming light from the first polarization to a second intermediate polarization;
• directing, using the second QWR, the second portion of the incoming light having the second intermediate polarization to a flat mirror;
• reflecting, using the flat mirror, the second portion of the incoming light having the second intermediate polarization back to the second QWR;
• changing, at the second QWR, a polarization of the second portion of the incoming light from the second intermediate polarization to the second polarization;
• directing, using the second QWR, the second portion of the incoming light having the second polarization onto the second surface of the PBS;
• directing, using the PBS, the second portion of the incoming light having the second polarization through the second surface of the PBS onto the detector array, wherein a second path of the second portion of the incoming light from the first lens to the detector array has a second length that is greater than the first length;
• determining first output of the detector array;
• and
• determining, based on the first output, first data indicative of a direction of incoming light relative to a predetermined point on the detector array.