This paper proposes a calibration method for angular positioning deviation of a high-precision rotary table based on the laser tracer multi-station measurement system. The algorithm error of the calibration method for angular positioning deviation of a high-precision rotary table based on the laser tracer multi-station measurement system was mainly discussed. During the experiments, the laser tracer was fixed on the work surface of the rotary table, and the rotary was fixed on the work surface of the coordinate measurement machine (CMM). The rotary table was rotated with the same angular interval. In this case, an optimization method for calculating the coordinates of a laser tracer station by using Levenberg–Marquardt algorithm and singular value decomposition transform was proposed. Then, the angular positioning deviation of the rotary table was calibrated by an established geometric relationship model between the coordinates of laser tracer stations and the rotation angle of the rotary table. The angular positioning deviation of the high-precision rotary table was as low as ±0.9″, and the error of the calibration method was ±0.4″. The experimental results proved the feasibility of the proposed calibration method. The calibration method proposed in this paper is suitable for the case that the rotary table is not linked with the CMM, especially for large high-precision rotary tables.

Ring laser gyroscope is one of the most important equipment in high-precision strapdown inertial navigation systems, and has been widely used in the field of navigation. At present, there is little research on the application of ring laser gyroscope on the angle error measurement of sub-arc-second in the metrology field, and it has not been officially used as the metrology standard instrument. Aiming at the inaccurate measurement of ring laser gyroscope in metrology due to zero position drift and non-coplanar installation, a non-contact high-precision angle measurement error measurement method is proposed in this paper. Firstly, the original scale factor is calculated on the standard rotating device to avoid re-calculated on the measured device and solve the traceability problem. Secondly, the influence of the installation error between the turntable and the laser gyroscope goniometer on the angle measurement error is analyzed, and the compensation method of angle measurement error in the online measurement of the laser gyroscope is proposed. Finally, the feasibility of online metrology of ring laser gyroscope is verified by experiments, and the measurement uncertainty is estimated. The online measurement results show that compared with the photoelectric autocollimator (measurement uncertainty is U = 0.07ʺ ( k = 2), the angle measurement error of the ring laser gyroscope goniometer in multi-axis turntable is ±0.4ʺ, and the measurement uncertainty is U = 0.36ʺ ( k = 2).

This paper gives a new application of laser gyro in the field of metrology, that is, the perpendicularity measurement method between two axes of multi-axis turntables based on single-axis laser gyro goniometer. This method skillfully establishes different coordinate frames on the turntable and uses the projection variation of the sensitive axis of the laser gyro in the coordinate frame to solve the perpendicularity. This method can also accurately solve the misalignment angle of the laser gyro goniometer at the same time. It is suitable for online measurement of perpendicularity between the axes of multi-axis turntables in fields such as CNC machine tools, robots, flight simulation, and inertial testing. This method has simple equipment installation, convenient measurement operation, high measurement accuracy (the measurement uncertainty is U = 0.23′′ (k = 2), and fully utilizes the dynamic characteristics of the laser gyro goniometer.

Rationale: Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is a rare autosomal recessive renal tubular disorder caused by mutations in the CLDN16 or CLDN19 genes. This case demonstrates the critical role of whole-exome sequencing (WES) in diagnosing FHHNC, particularly when novel mutations, such as the homozygous CLDN16 variant (c.351G > T, p.W117C) found in this patient, are identified, which expands the genetic understanding of this condition. Patient concerns: A 17-year-old female presented with an 8-month history of persistent neck, shoulder, and upper limb pain that had worsened over the past month. Despite initial treatment for cervical degenerative disease at local hospitals, her symptoms showed minimal improvement. She also exhibited growth retardation, with a height of 145 cm (−2 SD), and experienced recurrent urinary tract infections, although she reported no visual disturbances or neurological symptoms. Diagnoses: Laboratory tests revealed hypomagnesemia and elevated parathyroid hormone levels. Imaging studies confirmed bilateral nephrocalcinosis and a medullary sponge kidney. Genetic testing using WES identified a homozygous pathogenic mutation in CLDN16 (c.351G > T), which was further validated by Sanger sequencing in the patient and her heterozygous parents. Interventions: During hospitalization, the patient received intravenous magnesium sulfate (2.5 g/day), oral calcium carbonate with vitamin D3 supplementation, and levofloxacin for urinary tract infection management. Upon discharge, she was maintained on oral magnesium oxide (500 mg twice daily) with regular monitoring of electrolyte levels and renal function. Outcomes: At the 2-year follow-up, the patient’s serum magnesium levels improved but remained below the normal range. Hypercalciuria persisted, although her renal function was stable. Notably, there was no progression to end-stage renal disease, and her symptoms were better managed with ongoing treatment. Lessons: This case underscores the importance of WES in the diagnosis of rare tubular disorders, especially when the clinical presentations are nonspecific. This finding highlights that CLDN16-related FHHNC can occur without ocular involvement, and this information may aid in differential diagnosis. Early and consistent magnesium supplementation appears to mitigate renal deterioration, emphasizing the need for prompt intervention. Additionally, this case reinforces the value of genetic counseling for families affected by autosomal recessive conditions.