A multiple-beam triangulation-based range finder can direct multiple beams onto a sample from different orientations. The range finder can use a quadrant detector to detect light from the multiple beams that is reflected from the sample. The range finder generates a trigger signal when the target is a specified distance from the range finder. In some examples, two or more of the multiple beams are directed onto the sample simultaneously, where the beams are modulated at different frequencies and the signals from the quadrant detector are analyzed at the respective frequencies. In some examples, two or more of the multiple beams are directed onto the sample in succession, where the signals from the quadrant detector are analyzed in respective time windows. Using multiple beams with the quadrant detector can increase robustness against relative tilt of the sample with respect to the range finder.