Filtering the results of measuring the three-dimensional geometry of objects via the phase triangulation method under non-stationary lighting conditions

The article considers issues of improving the metrological characteristics of the phase triangulation method for measuring the three-dimensional geometry of objects. The stability of measurement results is shown to be affected by the nonstationarity of ambient lighting. A method is proposed for filtering data collected by a photodetector during measurements via the phase triangulation method under non-stationary lighting conditions. This method relies on the frequency analysis of collected data and their filtering according to the first harmonic amplitude in the frequency decomposition of the signal. The proposed method in the form of a filtering algorithm was experimentally tested in a measurement system implementing the phase triangulation method. The filtering results obtained via the developed method using the frequency analysis of collected data were compared with those obtained via the filtering method relying on the amplitude modulation analysis of signal intensity recorded by the photodetector. The comparative analysis of filtering results obtained using the two methods showed the higher effectiveness (by more than eight times) of the proposed filtering method. The study results can be useful in processing and analyzing experimental results, as well as contributing to the development of optical methods for measuring the three-dimensional geometry of objects.