Modeling of fiber-coupled confocal and interferometric confocal distance sensors
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In: Measurement Science and Technology Volume 33 / Number 7 (2022-04-06) , S. ; eissn:1361-6501
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Laser distance sensors are a widespread, fast and contactless approach for distance and surface topography measurements. Main characteristics of those sensors are given by resolution, measurement speed and sensor geometry. With decreasing sensor size, the alignment of the optical components in sensor setup becomes more challenging. The depth response of optical profilers is analyzed to obtain characteristic parameters and, thus, to value the alignment and the transfer behavior of those sensors. We present a novel miniaturized sensor setup comprising of confocal and interferometric confocal signals within one sensor in order to compare both principles simply by obscuring the reference arm by an absorber. Further, we introduce a theoretical signal modeling in order to analyze influences such as spatial coherence, Gaussian beam characteristics and tilted reflectors on depth response signals. In addition to this, we show that the coherent superposition significantly reduces the axial resolution due to the confocal effect in interferometric signals compared to simple confocal signals in measurement and simulation results. Finally, an appropriate fit function is presented, in order to figure out characteristic sensor parameters from the obtained depth response signal. In this context, a good agreement to simulated and measured signals is achieved.
@article{doi:10.17170/kobra-202205056137, author ={Siebert, Markus and Hagemeier, Sebastian and Pahl, Tobias and Serbes, Hüseyin and Lehmann, Peter}, title ={Modeling of fiber-coupled confocal and interferometric confocal distance sensors}, keywords ={600 and Hochgeschwindigkeit and Sensor and Signal and Optisches System and Mechanische Eigenschaft}, copyright ={http://creativecommons.org/licenses/by/4.0/}, language ={en}, journal ={Measurement Science and Technology}, year ={2022-04-06} }