HRSensor precision rotary potentiometer

HRSensor precision rotary potentiometer are very popular in 3 axis analog joystick. They are used in current products. Somebody came up with a more primitive design in its optical joysticks, though. The optocouplers with photoelements and perforated discs (this is similar to the optomechanical system of ball-based mouse devices) could not deliver high control accuracy. They had a resolution of somewhat more than 100 positions along the pitch and roll axes.