Patent ID: 8399909

Claim:
A position sensing detector comprising a photodiode having an active area and having a first corner, a second corner, a third corner, and a fourth corner, said photodiode comprising a. A semi insulating substrate layer; b. A buffered layer, wherein said buffered layer is formed directly atop the semi-insulating substrate layer; c. An absorption layer, wherein said absorption layer is formed directly atop the buffered layer; d. A cap layer, wherein said cap layer is formed directly atop the absorption layer; e. Four cathode electrodes electrically coupled to said buffered layer, wherein a first of said four cathode electrodes is positioned in the first corner, a second of said four cathode electrodes is positioned in the second corner, a third of said four cathode electrodes is positioned in the third corner, and a fourth of said four cathode electrodes is positioned in the fourth corner; and f. At least one anode electrode electrically coupled to a p-type region in said cap layer, wherein said detector is capable of detecting eye-safe wavelengths and wherein said p-type region is doped with an effective amount of metal such that a position detection error, in both the X and Y direction is on the order of 100 μm across the active area.