Phase Detected Triangulation: A New Twist On An Old Technology

A new approach to measuring range using triangulation is presented. In this approach, the triangulation angle is determined by spatially modulating the intensity of light in front of a single channel photodetector and then measuring the phase of the detector output signal. Using a single detector instead of the commonly used linear array or lateral effect photodivide, allows an increased signal to noise ratio and the possibility of faster measurement rates. Two possible application areas discussed are long range measurement (greater than one meter) and measurement of mirror like surfaces.