Differential-Type Encoder

The key components of an incremental encoder are a glass disk, LED (light emitting diode), and a photo detector. The transparent disk contains opaque sections which are equally spaced to deflect light while the transparent sections allow light to be passed through shown in Figure 2 below. An optical encoder utilizes a light emitting diode which shines light through the transparent portions of the disk. The light that shines through is received by the photo detector which produces an electrical signal output.