Compensation of surface inclination for detecting in optical triangulation sensors

Optical Triangulation Displacement Sensors (OTDSs) are widely used for their simple structure, high resolution, and long operating range. However, errors originating from speckle, inclination of the object, source power fluctuation, ambient light, and noise of the detector limit their usability. In this paper, we propose new design criteria for an error-reduced OTDS. The light source module for the system consists of an incoherent light source and a multimode optical fiber for eliminating speckle and shaping a Gaussian beam intensity profile. A diffuse-reflective white copy paper, which is attached to the object, makes the light intensity distribution on the charge-coupled device (CCD). Since the peak position of the intensity distribution is not related to the various error sources, a sub-pixel resolution signal processing algorithm that can detect the peak position makes it possible to construct an error-reduced OTDS system