Which component would most directly convert angular position to a digital count?

• A. Optical encoder
• B. Tachometer
• C. Controller
• D. Servo motor

Answer: (A)

Converting angular position into a digital count is what an optical encoder does. It attaches to a shaft and uses a light source and sensors to read a patterned disk. As the shaft turns, the pattern creates a stream of digital pulses that can be counted to determine the angle, and in many designs these pulses can also indicate direction. In an absolute encoder, that pattern encodes the exact position directly as a digital value, so you get a position readout without needing to count pulses.

The other components don’t perform this direct angular-to-digital conversion: a tachometer is used to measure rotational speed, not position; a controller processes signals but doesn’t itself convert angle into a digital count; a servo motor is the actuator that moves the load (it may include an encoder, but the conversion is done by the encoder itself).