Abstract
A novel sensing system is proposed for measuring a 2-D position of a laser spot. The sensing system determines the position by calculating voltages of phototransistors behind a screen in a sensor box. There are several advantages of the system, such as a simple sensing box with four phototransistors and a screen, wide incidence angle up to 85°, high-speed measurement of 400Hz, undivided position detection, robustness against background light and large detecting area of 50×50mm2. Some experiments validated the accuracy and the robustness of the position measurement, in which the maximum error of the position was 2mm in various conditions of incidence angle, distance, and illuminance of background light.
