2.4米望远镜高色散光谱仪自适应曝光系统研究

Lijiang High Dispersion Fiber Spectrometer is one of the main terminal scientific instruments of the 2.4-meter telescope,and the annual observation time is second only to YFOSC.The focus is on observations in areas such as stellar metal abundance, lithium-rich star discovery and certification, Study on the magnetic field activity of late-type stars, and exoplanet exploration.Since each target spectral acquisition requires a long exposure time, the conventional acquisition mode is a fixed exposure time acquisition mode.This method is easily affected by the weather conditions and instrumental efficiency, thereby affecting the observation efficiency.Therefore, the traditional fixed exposure time acquisition mode has not been able to meet the requirements of the 2.4-meter telescope for high-efficiency observations..This project will provide an overall study of the adaptive exposure system for high dispersion spectrometers.we will study the real-time measurement method of signal-to-noise ratio for different types of spectra and sub-spectral spectra. the final realization can automatically stop the spectral exposure and read out when the SNR meets different observation requirements.which will reasonably control the exposure time and improve the observation efficiency, the performance of the spectrometer and the telescope can be fully utilized.In addition.Thus the system is also applicable to the same type of instruments on the Lijiang station, such as exoplanet planetarium detector and 1.8-meter-fold axis spectrometer, etc. and related technologies can be popularized and applied at the same type of spectrometer at domestic and foreign.

丽江高色散光纤光谱仪是2.4米望远镜的主力终端科学仪器之一，全年观测时间仅次于YFOSC，重点服务于恒星金属丰度、富锂恒星发现和认证、晚型恒星磁场活动的研究及系外行星探测等领域的观测。由于每次目标光谱采集都需要较长的曝光时间，传统采集模式为固定曝光时间的采集模式。此方法容易受天气条件及仪器效率的影响，进而影响观测效率。因此，传统固定曝光时间的采集模式已经无法很好的满足2.4米望远镜对高效率观测的要求。. 本项目针对高色散光谱仪的自适应曝光系统提出整体研究方案，通过对不同类型光谱、分波段光谱对信噪比的实时计量方法的研究，最终实现可在信噪比满足不同观测需求时自动停止光谱曝光并读出，以合理控制曝光时间，提高观测效率，使光谱仪及望远镜的性能得到充分发挥。另外，该系统同样适用于丽江站的同类型设备上，例如：系外行星探测仪和1.8米折轴光谱仪等，相关技术可在国内外同类型光谱仪上推广应用。

经过三年的研究工作，在不断尝试后最终确定实施方案，并按计划基本完成项目任务的基本要求。本项目研究目标是通过对不同光谱类型的光谱、分波段对信噪比的实时计量方法研究，最终实现可在信噪比满足需求时自动停止曝光并读出，合理控制曝光时间以提高观测效率。按计划，项目通过对以下几方面进行深入研究：完成传感器线性测试；完成光谱波长定标；建立波长与像素对应关系；建立CCD光谱信号与PMT光子数的关系并对实际观测数据进行修正；结合仪器效率等完成利用PMT光子数对光谱信号仿真；开发了一套曝光量自动测量系统上位机软件；最后对2021年全年高色散光谱观测数据进行统计分析。项目从理论分析到数据处理、软件开发和观测数据统计，完成了一套对高色散观测不同光谱类型的光谱、分波段对信噪比的实时计量的方法，达到项目的研究目标。