A cross-capacitance liquid level sensor is based on the principle of cross capacitance. This study designed a new single-tube cross-capacitance fuel-level sensor. The fuel-level measurement model is established for a single-tube cross-capacitive sensor, and the relationship between the measured liquid level and sensor output capacitance is derived. The characteristics of the sensor were tested experimentally. The experimental results demonstrate that the linearity error of the liquid-level sensor of the single-tube calculation for the spacecraft is ±0.48%, the repeatability error is ±0.47%, and the hysteresis error is ±0.68%. The cross-capacitive fuel-level sensor developed in this study can be used in the fuel tank of spacecrafts owing to its low weight and high precision.

Cylindrical surfaces with complex parameters (CSCP), including off-axis, aspheric, and other properties, constitute fundamental components within complex optical systems. Two-dimensional pseudo lateral shearing interferometry (2DPLSI) is a non-null and generalized method for CSCP. It can eliminate wavefront error of components within systematic and retrace error, thereby achieving high-precision measurement. However, the accuracy of measurement is influenced by factors such as the parameters of the measurement system, rendering the analysis of measurement precision of 2DPLSI to be important. The sources of error in 2DPLSI are discussed in this paper; their effects are simulated using the Monte Carlo (MC) method. Furthermore, a wavefront construction method based on power spectral density (PSD) is proposed, which simulates actual wavefronts more effectively. In addition, experiments are conducted to validate the optimized measurement system parameters derived from the simulation results. Experimental results show that the optimized measurement system parameters effectively improve measurement accuracy, retain low-mid spatial frequency information of wavefront, and eliminate the influence of gridding artifacts.

As a key component in motion state sensing, the accuracy of accelerometers directly affect the performance and safety of their systems. However, their sensitivity can influenced due to various factors during operation, necessitating both pre-deployment and periodic calibration. Traditional primary calibration methods rely on laser interferometers, yet their trueness and stability are compromised by environmental disturbances affecting the laser wavelength, making on-site traceability challenging. Addressing these issues, this study combines a Cr self-traceable grating with a homodyne littrow grating interferometer and primary vibration calibration technique. Leveraging the high line density, stability, and traceability of the self-traceable grating, it achieves high accuracy and on-site traceable calibration. In experiments, the effectiveness of this calibration system was validated using commercial accelerometers, achieving a measurement uncertainty of 0.25%. This calibration technique not only enhances the accuracy and environmental adaptability of accelerometer calibration but also addresses the critical issue of on-site traceability, representing the future direction of in-field accelerometer calibration.