Improved measurement dynamic range for point triangulation probes

Point triangulation probes have been in use in industry for half a century. In that time, there has not been any big changes in the mechanism by which they operate A point laser triangulation gage bought today has about the same ratio of standard deviation to measurement range, or measurement dynamic range, as one bought 30+ years ago. A significant limiting factor of the measurement dynamic range of such sensors is the noise seen by the sensor, which consists of both classic speckle noise, but also the effects of surface texture on the reflected beam. This paper will discuss four different methods, based upon advances applied in other optical metrology systems that improve the standard deviation to measurement range ratio for point laser triangulation gages by a factor of 20 on average. We will present the theory of how each of these methods provide this improved measurement dynamic range as well as the results of laboratory tests made on breadboard systems.