Single Track Optical Encoder

A method of determining a position of a first mechanical component with respect to a second mechanical component, comprising:

• imaging, with an optical read head attached to the second mechanical component, a portion of an encoder track disposed on the first mechanical component, the encoder track having a first encoder scale extending along the encoder track and a second encoder scale extending along the encoder track, and the imaged portion of the encoder track including a first portion of the first encoder scale and a second portion of the second encoder scale;
• transforming the imaged portion of the encoder track to a spatial frequency domain;
• identifying a pair of frequency bins in the spatial frequency domain;
• determining a phase difference between a first frequency bin and a second frequency bin in the pair of frequency bins;
• and
• mapping the phase difference to a positional relationship between the first mechanical component and the second mechanical component.

An electronic device, comprising:

• a first mechanical component;
• a second mechanical component, movably coupled to the first mechanical component;
• an encoder track on the first mechanical component, the encoder track including an encoder scale comprising a set of two-dimensional (2D) sinusoids extending along a length of the encoder track;
• and
• an optical read head attached to the second mechanical component;
• wherein,
• the optical read head has a field of view including a portion of the encoder scale;
• and
• relative movement between the first and second mechanical components causes relative movement of the field of view of the optical read head along the encoder track.