E6F05

Which of the following describes an optical shaft encoder?

1. AA device that detects rotation by interrupting a light source with a patterned wheel
2. BA device that measures the strength of a beam of light using analog-to-digital conversion
3. CAn optical computing device in which light is coupled between devices by fiber optics
4. DA device for generating RTTY signals by means of a rotating light source

Pick an answer to check it.