Incremental optical encoders track position by counting what?

• A. Dots counted as pulses
• B. Colors on the disk
• C. Frequency of light
• D. Magnetic poles

Answer: (A)

Incremental optical encoders convert rotation into a series of pulses by using a disk that has a regular pattern of openings (dots) or slots. A light source shines through the disk and a photodetector senses when light passes through these openings. Each opening creates one pulse, so counting the pulses tells you how far the shaft has rotated. The more openings per revolution, the higher the resolution.

In practice, you often get direction information by using a second detector placed in quadrature with the first, but the basic idea remains that position is determined from the number of light interruptions or dots observed. Colors on the disk wouldn’t produce a clean, discrete pulse pattern the way openings do, and the frequency of light is a property of the source, not a count of discrete rotation steps. Magnetic poles relate to a different, magnetic-style encoder rather than optical.