For the purpose of realizing the dynamic angle measurement and calibration of the inertial equipment (such as rotary table), a dynamic angle measurement system based on the autocollimator and the fiber optic gyroscope (FOG), which can be used as an angle standard device, is designed in this paper. In this system, the scale factor of the FOG can be calibrated in the field application based on the autocollimator with the precision of 1 ^'' in the range of ±0.05°. Furthermore, the angle measurement deviation between the FOG and the rotary table can be limited in ±3 ^'' when the scale factor of the FOG is calibrated by the autocollimator when necessary. This research can guarantee the long-term accuracy of the scale factor of the FOG in the field application and it will greatly promote the applications of the FOG as an angle standard device in the field of dynamic angle measurement.

This paper proposes a 3D point cloud segmentation algorithm based on a depth camera for large-scale model point cloud unsupervised class segmentation. The algorithm utilizes depth information obtained from a depth camera and a voxelization technique to reduce the size of the point cloud, and then uses clustering methods to segment the voxels based on their density and distance to the camera. Experimental results show that the proposed algorithm achieves high segmentation accuracy and fast segmentation speed on various large-scale model point clouds. Compared with recent similar works, the algorithm demonstrates superior performance in terms of accuracy metrics, with an average Intersection over Union (IoU) of 90.2% on our own benchmark dataset.

Research on the transfer and traceability of a dynamic angle has great value in the field of measurement. The fiber optic gyroscope (FOG), as a high-precision angular velocity sensor, has broad prospects in this application. The focus of this article is the evaluation of angle measurement uncertainty of the FOG based on the Monte Carlo method (MCM). The angle measurement uncertainty evaluation model is established based on the principle of the FOG, and the simulation is carried out in detail based on the model and MCM. Finally, the angle measurement experiments of the FOG are carried out in the National Institute of Metrology, China. The experimental results show that the angle measurement uncertainty within the range of 360° is about 0.96 ^'' in a relatively stable environment when the confidence probability is 95%. It is highly consistent with the simulation, which confirms the accuracy of the evaluation model and the effectiveness of MCM.

The multifunction integrated optical chip (MIOC) is one of the most critical parts of the interferometric fiber optic gyroscope (IFOG), and research on the halfwave voltage of the MIOC is meaningful for a high-precision IFOG. In this paper, the correlation between the frequency and halfwave voltage, which affects the interference light intensity of IFOG, is presented theoretically. A widespread measurement method for frequency dependence of the halfwave voltage, based on lock-in amplification and sinusoidal modulation, is proposed. Further, the measurement result and the oscillation of interference light intensity in the Sagnac interferometer are presented, which are in great agreement with the theory. This paper proposes the frequency dependence of the halfwave voltage and provides a new error research direction for the improvement of the MIOC in a high-precision IFOG.

Primary angular vibration calibration devices based on laser interferometers play a crucial role in evaluating the dynamic performance of inertial sensing devices. Here, we propose a sinusoidal phase-modulated angle interferometer (SPMAI) to realize angular vibration measurements over a frequency range of 1–1000 Hz, in which the sinusoidal measurement retro-reflector (SMR) and the phase generation carrier (PGC) demodulation algorithm are adopted to track the dynamic angle variation. A comprehensive theoretical analysis is presented to reveal the relationship between demodulation performance of the SPMAI and several factors, such as phase modulation depth, carrier phase delay and sampling frequency. Both the simulated and experimental results demonstrate that the proposed SPMAI can achieve an angular vibration measurement with amplitude of sub-arcsecond under given parameters. Using the proposed SPMAI, the frequency bandwidth of an interferometric fiber-optic gyroscope (IFOG) is successfully determined to be 848 Hz.

A novel fiber-optic magnetic field sensor, based on a Sagnac structure, is proposed with the approach of polarization interference detection. The sensor takes advantage of common path interference, combining with a high magnetic field sensitivity sensing unit, composed of magneto-optical crystal, and magnetic field concentrators, to achieve high resolution, high stability, and large dynamic measurement of DC magnetic field signals. In this paper, the theoretical model is established and the related theory is derived in detail. The key technologies in the system are thoroughly investigated and verified. Experimental research on the proposed system is demonstrated and the results show that a DC magnetic field resolution of 5.6 nT and a dynamic range of larger than 70 dB is achieved. Furthermore, the linearity of the system is greater than 99.8% and the instability is less than 0.5%.