This PDF file contains the front matter associated with SPIE Proceedings Volume 12965, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

This paper delves into the investigation of morphing capabilities in a unimorph deformable mirror within the context of Active Optics applications, specifically when exposed to environmental factors in space. The study encompasses an array of factors that contribute to disturbances, encompassing intricate thermal and mechanical conditions that impact the ferroelectric properties of strain actuation. The study also focuses on the effects of stress-induced geometric stiffness on the mirror's structural rigidity. In addition, the paper envisions the potential utilization of these mirrors in lightweight satellite systems.

The Educational Adaptive-optics Solar Telescope is the most advanced solar telescope available for scientific education currently. However, in some situations, strong atmospheric turbulence or equipment failure cause the solar adaptive optics system to fail, resulting in high-resolution imaging systems only being able to record open loop solar images with low quality and a lack of detailed texture information. Traditional image interpolation algorithms have limited expressive capabilities, however deep-learning methods can be trained for generating high-quality images from paired data sets. Our research is based on Real-ESRGAN, a powerful deep neural network that is utilized to solve real-world single image super-resolution reconstruction problems. We select 130 close loop TiO band (7057Å) images recorded on 2022 August 4 and another 203 on 2022 September 22 as the training datasets. For two representative examples, we evaluate the effect of image reconstruction from open loop images, and the peak signal-to-noise ratio and the structural similarity index measurement values of the reconstructed images generated by Real-ESRGAN are higher than those obtained using open loop data. As a result, some reconstruction image generated by Real-ESRGAN from the open loop solar image can be used some supplementary data.

Horizontal atmosphere will obviously distort the light spot notably and attenuate the transmission efficiency of a laser eavesdropping. However, the contributions of ambient parameters to the transmission efficiency of laser eavesdropping are still unknown. Therefore, the influence of horizontal atmospheric fluctuation on the transmission efficiency of laser eavesdropping is investigated by carrying out theoretical analysis and validation. The mean and standard deviation of the fluctuation of the ambient variables are adopted to analyze the influence on the transmission efficiency and the statistical conclusions are attained, which can be used to predict the mean transmission efficiency. To improve the transmission efficiency, a new method based on Gerchberg-Saxton (GS) phase retrieval algorithm is proposed by integrating a Nicol grating into the optical system, hence the configuration is simple and the size is compact. The experimental results reveal that the transmission efficiency is notably improved after GS correction. The proposed method is proved to be feasible.

Aiming at a series of problems caused by the position sensor required by the salient pole permanent magnet synchronous motor (IPMSM) control system, a high-frequency square wave injection sensorless control algorithm suitable for IPMSM low-speed control system is realized in this paper. Compared with other sensorless control algorithms, its advantages are that it avoids the system delay caused by the filter by injecting high-frequency square wave signal, and has good stability and robustness at low speed. The feasibility and effectiveness of this method are verified by simulation. At the same time, it shows that the high-frequency square wave injection method has good accuracy of rotor position estimation, and can ensure the good stability and dynamic performance of the whole drive system. Through the simulation results, better injection voltage amplitude is selected to reduce the electromagnetic interference and electromagnetic noise caused by high-frequency square wave injection signal.

Parallel observation of a large number of astronomical spectra in the night sky has become an urgent need with the increasing development of astronomy. We are currently entering a new era of ultra-large-scale fiber optic spectroscopic telescopes. To improve observation quality, many major telescope projects around the world are making their focal planes smaller and smaller. At the same time, to ensure observation efficiency and parallel observation of more target celestial bodies, the spatial density of fiber positioners used to guide fiber optic reception of celestial spectra on multi-spectral telescope focal planes is also increasing. Multi-target fiber optic spectroscopic telescopes require the use of more numerous and smaller fiber positioners, which inevitably necessitates smaller mechanical structures, as well as the development of miniaturized motors used to drive rotational axis. To adapt to the trend of miniaturization and efficient driving of fiber positioner on the focal plane, many fiber positioner design schemes in focal plane systems are beginning to consider using smaller hollow cup Permanent Magnet Brushless motors as a replacement for the widely implemented Faulhaber micro stepper motors as a driving source for rotational movement. However, for a micro brushless motor with a Φ 4mm, there is a lack of original encoder solutions that are compatible with it and can be used for fiber positioner at the very small sizes needed, and motor suppliers have no corresponding plans in this field. Researchers have developed a micro magnetic encoder solution at the end of the sensorless Φ 4mm micro hollow cup motor to achieve closed-loop field-oriented control (FOC) of the motor. The solution uses a diametrically magnetized permanent magnet with a diameter of only 2mm and a height of 1.5 mm and a diameter 4mm miniature printed circuit board (PCB), which is equipped with a 2mm × 2mm magnetic encoder chip for detecting the phase of the airgap magnetic field of the magnet. When the rotor of the motor drives the magnet on the shaft to rotate, the magnetic encoder chip can detect the phase change of the magnetic field in real-time rotor angle position provided by the magnetic encoder chip and generates an excitation magnetic field that is 90° ahead of the rotor magnetic field in the motor stator coil in a timely manner. This measure can significantly improve the energy utilization efficiency of the motor in the fiber positioning process on the focal plane of a multi-spectral telescope and reduce the additional thermal impact caused by the driving system. Compared with the existing open-loop driving method for micro motors, the introduction of a micro position sensor can also respond promptly and power off in case of unexpected motor blockage, reducing damage to individual mechanical components caused by blockage. In addition, the closed-loop system of the micro motor can further improve the fiber positioning accuracy of the focal plane system, solve the step loss problem caused by open-loop driving motors, and realize the world's smallest micro-servo control system. This paper focuses on the development ideas, methods, and technical implementation of the motor magnetic encoder system in miniature fiber positioners, and successfully assembles and applies the magnetic encoder system in the center shaft mechanism of the miniature fiber positioner in the new generation of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST).

An improvement project for LAMOST is to be implemented soon. In order to reduce the heat generation of the drive system and improve the observation accuracy. In this paper, an ultra-low power drive system for an integrated fiber positioner robot is designed, and its hardware drive circuit and low-power software driver are described in detail. Each module in the hardware driver circuit is designed with its size and power consumption in mind, and the driver board is powered by time-sharing and partitioning. A task scheduling mechanism based on STM32 low-power mode is designed in the software driver of the fiber positioner robot, which analyzes the idle state between tasks when it receives a control command task, and selectively enters the low-power mode after executing the drive task in each round. In order to evaluate the low-power characteristics of this ultra-low power drive system, we built a power consumption measurement platform. The experimental results show that the static power supply current of each driver board in this designed ultra-low power driver system is 16.20mA, and its static power consumption is reduced by 92.50% compared with the previous generation of fiber positioner robot driver boards.

The scientific research mission of the China Survey Space Telescope (CSST) imposes rigorous requirements on the observation precision. The survey module is the most important scientific payload of the CSST and will conduct the wide-field multiband imaging and slitless spectroscopy survey at a resolution close to that of the Hubble Space Telescope. The focal plane of the survey module is the imaging part of the CSST, and carrying its dynamics performance research has great theoretical significance and engineering value. First, based on the transfer path analysis theory, the transfer path analysis model of the focal plane assembly is established, and vibration experiments are conducted to investigate the transfer mechanism of micro-vibration within the focal plane assembly. The results of this study can provide substructure dynamic data for the overall dynamic analysis of the CSST, enabling the direct acquisition of focal plane vibration response data in accordance with the input values from vibration sources in subsequent analyses. Secondly, the modal parameters of the focal plane assembly are obtained by using the hammering method to conduct modal analysis experiments on the focal plane components in two states: installed and free. These research results provide data support for determining whether the survey module meets the fundamental frequency requirements of the spacecraft. The results show that the modal parameters of the focal plane assembly meet the engineering requirements, affirming the correctness of the structural design. The research results of this paper also provide a basis for the subsequent structural dynamic optimization of the survey module and CSST.

A composite piezoelectric deformable mirror (DM) with woofer-tweeter configuration is proposed for astronomy applications. This DM consists of unimorph DM and piezoelectric actuators array. Compared with conventional DM, the composite piezoelectric DM has a characteristic of both large stroke and high bandwidth, which is suitable for correcting those aberrations introduced by atmospheric turbulence in real time. The prototype of the composite DM is prepared, and an adaptive optical testing system based on Shack-Hartmann sensor is established. Experimental results indicate that the woofer–tweeter DM has the capability to compensate for the first 20 terms of Zernike aberrations with normalized RMS wavefront errors less than 15%. The proposed composite piezoelectric DM has good performance and great potential in astronomical applications.

According to requirements, a co-aperture design has been performed for the visible light remote sensing camera and the synthetic aperture radar, allowing the remote sensing satellite to acquire both visible light and radar images simultaneously. The front system is a two-mirror, no-focus system with a primary mirror diameter of 3 meters, serving to compress the beam. To avoid obstruction, the primary mirror is placed off-axis. The visible light component consists of an off-axis three mirror system, with the entrance pupil aligned with the exit pupil of the front system. All three mirrors are secondary mirrors with quadratic surfaces. The primary mirror size is 500mm, and the system's focal length is 7.22m. The overall ground resolution of the system reaches sub-meter level, with a full field of view measuring 0.8° × 0.03°. Optical design software ZEMAX was employed to evaluate the imaging quality within the visible light wavelength range. The results indicate that the spot size of the system is smaller than 13μm within each field of view. At the Nyquist frequency, the modulation transfer function (MTF) values for each field of view exceed 0.4, approaching the diffraction limit, showcasing good imaging quality. This design enhances the satellite's adaptability and observational capabilities, reduces the overall size of the instrument, and saves on manufacturing and launch costs.

The successful achievement of the scientific objectives of the Visible Telescope (VT) in the Space Multi-band Variable Object Monitor (SVOM) mission relies heavily on high-precision quantum efficiency calibration. The calibration process for the VT CCD presents a challenge due to the requirement for extremely low radiation levels given the long integration time of the CCD. To address the difficulty in accurately measuring such low radiance, a two-step calibration method is employed. This method involves the use of two photodiodes, one positioned at the CCD location and the other in an integrating sphere. In the first step, the proportional relationship between the measured illuminance values of the two photodiodes is calibrated under high illumination conditions. This step establishes a reliable reference for subsequent calibrations. In the second step, the CCD is calibrated using the integrating sphere photodiode under low illumination conditions. The measured illuminance is then converted to the CCD position. Experimental results have demonstrated the effectiveness of this two-step calibration method, achieving a quantum efficiency calibration uncertainty of 1.7%. This approach provides a reliable and accurate means of calibrating the quantum efficiency of the CCD in the VT instrument.

The field of view of optical imaging systems is limited, making it difficult to meet the needs of continuous tracking of multiple targets in different orientations in a wide spatial domain, even in the 4 π spatial domain. Therefore, based on the two-dimensional tracking rotating platform, an unscented Kalman motion estimation algorithm based on target motion characteristics and an optimization algorithm for multi-objective switching tracking based on motion target matching, tracking convergence, and platform rotation ability have been proposed. The ultimate goal is to achieve continuous tracking of multiple spatial targets over a wide area. The development of a light and small space two-dimensional rotating platform tracking system is completed. The target detection coverage achieved is better than ± 180° in both pitch and azimuth directions. Continuous observation and tracking of better than 8 targets has been achieved through target motion estimation and switching tracking methods.

Current astronomical detection of Positronium (Ps) atoms through gamma-ray emission is inherently limited by a 3-degree angular resolution. Alternatively, the triplet state of Ps is capable of producing a recombination spectrum in the near-infrared band, which would provide the potential to increase the angular resolution by a factor of 10⁴ . The most promising signature is the Ps Balmer alpha line (Psα) at 1312.22nm. This observation scheme has never been implemented from ground-based telescopes due to the bright airglow. Now, the FBG-based OH suppression technique presents a promising solution for removing airglow emission lines surrounding the target signature. In this proceeding, we present the design and fabrication details of the first astronomy J-band FBG filters and early results of the OH suppression unit specifically developed for Ps detection.