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The photoelectric sensing unit in a large-space measurement system primarily determines the measurement accuracy of the system. Aiming to resolve the problem whereby existing sensing units have difficulty accurately measuring the hidden points and free-form surfaces in large components, in this study, we designed a multi-node fusion of a combined sensor. Firstly, a multi-node fusion hidden-point measurement model and a solution model are established, and the measurement results converge after the number of nodes is simulated to be nine. Secondly, an adaptive front-end photoelectric conditioning circuit, including signal amplification, filtering, and adjustable level is designed, and the accuracy of the circuit function is verified. Then, a nonlinear least-squares calibration method is proposed by combining the constraints of the multi-position vector cones, and the internal parameters of the probe, in relation to the various detection nodes, are calibrated. Finally, a distributed system and laser tracking system are introduced to establish a fusion experimental validation platform, and the results show that the standard deviation and accuracy of the three-axis measurement of the test point of the combined sensor in the measurement area of 7000 mm × 7000 mm × 3000 mm are better than 0.026 mm and 0.24 mm, respectively, and the accuracy of the length measurement is within 0.28 mm. Further, the measurement accuracy of the hidden point of the aircraft hood and the free-form surface is better than 0.26 mm, which can meet most of the industrial measurement needs and expand the application field of large-space measurement systems. [ABSTRACT FROM AUTHOR]

Mode matching has proven effective in suppressing the mode hopping in external cavity diode lasers (ECDLs) without antireflection coating. However, prolonged operation of ECDLs is susceptible to mode hopping induced by fluctuations in the equivalent internal cavity length. In this study, we introduce a rapid mode hopping identification method by monitoring the first derivative of the frequency scanning interference signal. Subsequently, an adaptive mode hopping suppression method, based on the acquisition of a priori knowledge for the initial current traversal optimization range, is applied to ECDLs. The experimental results demonstrate a significant extension in the stable operation time of the ECDL by a factor of 17, surpassing 7 h using the proposed rapid adaptive mode hopping suppression method. [ABSTRACT FROM AUTHOR]