Measurements of inclination angle and distance of curved mirror using LED light sources

There is a demand for measuring the inclination angle of a convex mirror or a concave mirror (curved mirror) used for a door mirror of a vehicle and a virtual screen display, etc. with non-contact method using an optical system. Therefore in this study, we aim to develop the device that has a simple structure using four infrared LEDs as light sources and a two-dimensional PSD (position sensitive detector). This sensor can measure the inclination angle and distance of the convex mirror or the concave mirror with a high degree of accuracy by utilizing a curvature coefficient depending on the curvature radius of a curved mirror. As the result of experiments, the measurement accuracy of the angle is within ±0.5 degrees and the distance L from the sensor to the mirror can be measured with ±5 percent accuracy that indicates a sufficient accuracy.