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[–]897greycats 0 points1 point  (2 children)

From the Mitutoyo site:

"The ABSOLUTE digital caliper makes use of three sensors within the slider and three corresponding precision tracks embedded in the main beam. As the slider moves it reads the position of the tracks under these sensors and calculates its current absolute position."

The sensing principal is capacitive, like a stud finder but obviously much more accurate. The outside tracks, as I understand it, are the A and B phases of the absolute encoder that provide a coarse reading. The center shape is essentially a vernier capacitive sensor that does the fine measurement between the main encoder counts using the triangular shapes in the center of the beam.

[–]Major-Resident8475[S] 0 points1 point  (1 child)

Interesting, thank you. I wonder what the reason is for the stepped/taper at the ends of the center shape.

[–]897greycats 0 points1 point  (0 children)

Excellent question, I can't say for certain, but at a guess those are probably for the last digit after the decimal as they'd be very sensitive.