This is a thirteen-track absolute position grey-code encoder.
Thirteen bits of code gives resolution of (360 degrees)/(213) = 0.044 degrees.
It is no wonder that the camera used to take this photograph did not have enough
resolution to accurately represent the outer two tracks.
The zero position (code in binary is "0 0000 0000 0000") is between "noon" and 1 o'clock. (The dark "V" shape pointing outward.)
The "1 1111 1111 1111" code is between 8 and 9 o'clock. (Why not right next to the "0 0000 0000 0000" code?)
There is some damage to the track from disassembling the product. The damage is near the bottom of the image.
This image is 1135 by 1124 pixels. For a clear view you need to view it at full resolution.
Full resolution means the outer diameter of the body of this encoder is typically shown on-screen at about 9 or 10 inches across.
If your screen is not large enough to show a full 9 or 10 inches of diameter, zoom in and pan the image to view part of it at full resolution.
The link below to Wikimedia Commons will give you a full-color version of this photo.
Image source: Wikimedia Commons, then Gimped and cropped to highlight the track detail.
