高重复频率DPL激光辐照光学薄膜元件温升规律实验研究

The temperature rise of optical films under DPL-pulsed laser irradiation of high repetition rate

光学薄膜是激光系统中最易损坏的薄弱环节。在高重复频率脉冲激光辐照下光学薄膜表面温度急剧上升,导致膜层应力、结构发生变化,最后出现宏观的灾难性损伤。文章采用红外热像仪实时测量了重复频率10kHz的DPL脉冲激光辐照下光学薄膜元件表面激光辐照中心点的温度变化,分析了影响薄膜元件温度变化的众多因素。结果表明,采用热导率较大的材料作基板的薄膜样品表面的温升较低;基板厚度越大的薄膜样品表面温升越低;薄膜表面激光辐照中心点的温度与样品的吸收峰值功率密度呈线性关系。

Optical coatings are the uttermost weak link in the laser system and may easily be damaged. The temperature of films rises quickly under the irradiation by a pulsed laser of high repetition rate, that leads to a sharp variation of the stresses in the coatings and their configurations, and is followed by macroscopic and catastrophic damages. In this paper, we measured the maximal temperature variation in films irradiated by DPL laser with repetition rate of 10 kHz in real time using infrared thermography camera and analyzed the factors that can affect the temperature variation in coatings. The results indicate that the temperature rise of coatings decreases with the increase of thermal conductivity of the substrate, and with the increase of thickness. The relationship between the maximal temperature rise of films and absorbing power density is almost linear.