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金属镜面反射镜是反射式天文望远镜中成像系统的核心部件,反射镜定期清洗是天文望远镜维护中的一项重要工作.目前采用的干冰人工清洗方法工序繁杂,成本较高,还需要定期使用清洁剂和清洁布擦拭的方法去除难以清洗的污染物,容易损伤镜面.针对以上缺点,本文利用放大级飞秒脉冲激光器,对天文望远镜中反射表面上黏附的微米级灰尘颗粒进行了清洁研究.首先研究了飞秒激光与反射铝镜的作用规律,通过调节激光能量密度,对清洗后的铝镜表面形貌进行观测,得出实验用铝镜的飞秒激光损伤阈值为60 m J/cm2.通过改变激光能量等扫描参数,对清洁前后的铝镜镜面附着物进行分析,得到最优的清洁参数.结果表明,当激光能量密度为30~55m J/cm2时,飞秒激光对微米级灰尘颗粒有良好的清洁效果.在可见光范围内,清洁后的反射镜镜面反射率获得了明显的提升.最后,通过对灰尘颗粒及铝镜基底的能谱分析,对飞秒激光的清洁机理进行了讨论,在灰尘颗粒的激光清洁中热膨胀因素占据主导作用.飞秒激光清洁在天文望远镜的清洁领域有着良好的应用前景.
Metal mirror is the core component of the imaging system in the reflective telescope, regular cleaning of the mirror is an important task in the maintenance of the telescope.Currently, the dry ice manual cleaning method is complicated and costly, and needs regular cleaning Agent and cloth cleaning method to remove difficult to clean contaminants, easy to damage the mirror.In view of the above shortcomings, this paper uses the magnification level femtosecond pulsed laser to clean the microscopic dust particles adhered to the reflecting surface of the telescope. The law of the action of the femtosecond laser and the reflective aluminum mirror was studied. By adjusting the laser energy density, the surface morphology of the cleaned aluminum mirror was observed. The experimental femtosecond laser damage threshold of the experimental aluminum mirror was 60 m J / cm2. By changing the laser energy and other scanning parameters, the mirror attachment of aluminum mirror before and after cleaning was analyzed to obtain the optimal cleaning parameters.The results show that when the laser energy density is 30 ~ 55m J / cm2, the femtosecond laser on the micron dust Particles have a good cleaning effect in the visible range, the mirror reflectivity after cleaning has been significantly improved.Finally, by Dust particles and the aluminum mirror substrate energy spectrum analysis of the femtosecond laser cleaning mechanism is discussed in the dust particles in the laser cleaning thermal expansion dominant factor femtosecond laser cleaning in the field of astronomical telescopes has a good prospect of application .