提出了一种离线精确测定金属铝薄膜光学常数的方法。与传统的原位测量方法相比,这种方法简便,不需要连接到真空室的复杂测量设备上。该方法以测量椭偏光谱曲线和分光光谱曲线为目标,考虑金属铝薄膜在空气中表面氧化的影响,在混合优化算法的基础上,使用基于色散关系的多波长法拟合确定金属铝薄膜从紫外到可见区(200～800 nm)的光学常数;优化算法采用多种群并行遗传算法和单纯形法相结合的方式,提高了拟合质量和速度,得到了理想的结果,光谱曲线拟合误差<2%。在确定了铝光学常数的基础上,镀制了单腔紫外诱导透射滤光片,测量的透过率光谱与设计结果在265 nm处的峰值透过率偏差<1%。

An ex-situ determining method was proposed for the optical constants of aluminum thin films precisely.Compared to the traditional in-situ method,the method had no need of the complex optical measurement apparatus attached to vacuum chamber and could do measurement simply and fastly.By using multi-wavelength fitting method,the ellipsometric and photometric spectra were fittd with a combination of optimal genetic algorism and a simplex algorism and the oxide layer formed on the aluminum in air was considered in the fitting process.With the combination of parallel genetic algorithm and least square method,the fitting speed and quality were obviously improved and the optical constants from the UV to visible range were obtained within an error no more than 2%.With these data known,an UV induced transmission filter with one cavity was designed.The tested transmission spectra are well consistent with that design in a peak transmittance error less than 1% at 265 nm.