Abstract: An optical control in the form of a rotary optical encoder includes a Gray code generating disk (9), a light source (3), a series of three light detectors (4), and an apertured cover (5) arranged over the light detectors (4). The control further includes a reflector (12) which redirects the light from the light source (3) to the detectors (4). The reflector (12) comprises a first parabolic reflective surface (14) which reflects the incident light from the light source (3) into a number of parabolic secondary reflective surfaces (15), each of which reflects and concentrates the light through the apertured cover (5) towards a particular light detector (4).