In this article, a kind of edge sensor based on the eddy current effect is proposed to realize accurate detection of the nano-level resolution in large temperature span. Compared with edge sensors with different principles used in optical telescope projects, eddy current edge sensor has the advantages of being insensitive to non-target direction and immune to non-ferromagnetic medium. The proposed dual-differential edge sensor(DDES) greatly simplifies its installation, and reduces the number of support components for sensors to half by replacing the complementary symmetrical installation method. By analyzing the detection principle, a kind of precise demodulation circuit and real-time temperature compensation method are also designed to guarantee the sensor ultra-high stability. The prototype of the sensor is manufactured and verified that the resolution can reach within 2nm in the range of 300μm, and the temperature drift performance is less than 6nm/°C under the large temperature span of -25°C-+25°C. The installation error measurement convinced that the current structure has an excellent installation error tolerance, which has the potential to applying in engineering application of astronomical telescope mirror splicing.

The current cofocus maintenance strategy of the primary mirror of the Large Sky Area Multi-Object Spectroscopic Telescope (Mb) using Shack–Hartmann Wavefront Sensor (SHWFS) interrupts the observation mission. This study proposed an Eddy current edge sensor with high precision and accuracy to achieve closed-loop cofocus control. Through structural design, interaction matrix deduction, installation parameter analysis, and performance calibration, the edge sensor was validated for use in detecting segment attitudes. The minimum cofocus maintenance system comprising three segments was separated from Mb and established to validate the effectiveness of the closed-loop cofocus control with the novel edge sensor. The closed-loop control system was effective within less than 1.5°C environmental temperature changes after 13 h, which is considerably longer than the maintenance time with the SHWFS. Moreover, continuous observation without interruption is possible during one observation night.

Polycrystalline gallium oxide thin film was prepared using electron-beam evaporation and a post-annealing treatment. Cathodoluminescent measurement show the gallium oxide thin film has emission peaks ranging from 300 to 650 nm. Using gallium oxide thin film anode, a flat panel UV light source was fabricated by using ZnO nanowires field emitter arrays.

This study introduces a novel method to increase the stability of the balance point in precision differential eddy current sensor (ECS) displacement sensors, which is crucial for achieving optimal performance and improving the interchangeability of sensor probes. The temperature drift coefficient at the electrical balance point (BTC), a common issue affecting the accuracy and reliability of measurements, is addressed through our approach. The BTC can be accurately adjusted by fine-tuning the length of the aluminum target, which aligns the zero-temperature drift position with the electrical balance position, thereby achieving a perfect balance point. The experimental results demonstrate that the proposed method significantly reduces the temperature drift near the balance point of the differential ECS. The BTC was effectively reduced from −7.21 nm/°C to 0.22 nm/°C. This substantial reduction in the BTC enhances the stability of the sensor, facilitating more reliable measurements in high-precision applications.

A method for the co-focus closed-loop control of segmented primary mirrors in astronomical telescopes is proposed based on pose detection. The pose changes of each segment relative to a reference segment are calculated by constructing a pose estimation matrix. Subsequently, the required actuation values for each segment are computed using the pose-to-actuation mapping matrix. The parameter analysis evaluates the noise characteristics of a system composed of four segmented mirrors. Experimental validation on a four-segment subsystem of the LAMOST primary mirror Mb demonstrates that the proposed co-focusing control method can converge the system focal spot to within 0.1 arcsec even under temperature variations exceeding 12°C, and thus enables the long-term confocal maintenance during continuous operation.