Abstract: A circuit (10) for driving a laser diode (12) includes a fixed current source (14), a programmable current source (16), a differential output driver (18), a phase splitter (20), and a ring oscillator (22). The fixed current source (16) is always coupled to the laser diode (12) and supplies a few milliamperes (well below the current required to make the diode lase) in order to maintain forward voltage on the laser (12). The programmable current source (16) is alternately coupled to the anode (12a) and the cathode (12b) of the laser diode (12) by the differential output driver (18) in response to signals from the phase splitter (20). The phase splitter (20) changes phase at a frequency controlled by the ring oscillator (22). According to a presently preferred embodiment, a 25% duty cycle in the ring oscillator (22) keeps the laser diode (12) ON for 75% of the time. The frequency of the laser diode (12) is nominally 300-500 Mhz.

Abstract: A position sensor and a method of creating the same which sensor has an incoherent light source, multiple light detectors and a sinusoidal pattern that can be directly installed to the sensor. The light source and detectors are positioned along the axis of motion of the element whose position is to be determined. In a device containing such a movable target element, light from the sensor is directed through the sinusoidal pattern to and reflected from a periodic reflection profile to create detectable sinusoid signals that can be used for positioning purposes.