Patent ID: 8767219

Claim:
A method for sensing the position of an incident optical beam in a plane perpendicular to its traveling direction and converting the position to an electrical signal, the method comprising: a) providing a symmetric partioning element having a sharp edge which is able to spatially dissect said optical beam into a first dissected beam and a second dissected beam; b) providing a first photo detector which is able to convert the light signal of said first dissected beam into a first electrical signal; c) providing a second photo detector which is able to convert the light signal of said second dissected beam into a second electrical signal; d) providing a first voltage source which is able to apply a positive voltage to the cathode of said first photo detector with respect to the voltage of the anode of said first photo detector; e) providing a second voltage source which is able to apply a negative voltage on the anode of said second photo detector with respect to the voltage of the cathode of said second photo detector; f) providing an electrical connection between the anode of said first photo detector and the cathode of said second photo detector to obtain a difference signal from said electrical connection; whereby said difference signal provides a measure for the position of said optical beam in a plane perpendicular to its traveling direction with respect to the position of said symmetric partioning element, and the position of said optical beam can be measured with a minor delay caused by the applied reverse bias voltage on the junction capacitance of the photo detectors, and with a minor temperature drift caused by the symmetric shape of the partioning element, and with a minor dead gap caused by the sharp edge, and without having to obtain the difference signals using any active amplifier stage caused by the electrical connection between photo detectors.