Hutcheson E T, Hass G, Cox J T
Appl Opt. 1972 Oct 1;11(10):2245-8. doi: 10.1364/AO.11.002245.
Freshly deposited aluminum prepared under optimum conditions was overcoated with MgF(2) and LiF films at various deposition rates and substrate temperatures. The thickness of the dielectric films was precisely controlled by reflectance measurements at lambda = 1216 A. The thicknesses of the MgF(2) and LiF films were chosen to give highest reflectance at 1216 A and 1026 A, respectively, and the reflectance was measured from 1000 A to 2000 A. Highest reflectance for aluminum overcoated with MgF(2) was obtained with a MgF(2) deposition rate of about 45 A/sec. When the MgF(2) deposition rate was decreased from 45 A/sec to 5 A/sec, the reflectance at 1216 A decreased from 85.7% to 78%. A decrease in reflectance was also noticeable for deposition rates higher than 45 A/sec. No improvement in reflectance was noted for substrate temperatures up to 100 degrees C, and at temperatures above 100 degrees C the reflectance decreased. The reflectance of aluminum overcoated with LiF did not show a measurable dependence on the LiF deposition rate, but the reflectance was strongly influenced by the substrate temperature. Highest reflectance at 1026 A was obtained when the LiF was deposited at a substrate temperature of 100 degrees C. The effects of aging on the reflectance of the mirrors are discussed.
在最佳条件下制备的新沉积铝，在不同沉积速率和衬底温度下用MgF₂和LiF薄膜进行了覆盖。通过在λ = 1216 Å处的反射率测量精确控制介电薄膜的厚度。选择MgF₂和LiF薄膜的厚度分别在1216 Å和1026 Å处给出最高反射率，并在1000 Å至2000 Å范围内测量反射率。用约45 Å/秒的MgF₂沉积速率获得了MgF₂覆盖铝的最高反射率。当MgF₂沉积速率从45 Å/秒降低到5 Å/秒时，1216 Å处的反射率从85.7%降低到78%。对于高于45 Å/秒的沉积速率，反射率的降低也很明显。对于高达100℃的衬底温度，反射率没有改善，而在高于100℃的温度下反射率降低。LiF覆盖铝的反射率对LiF沉积速率没有可测量的依赖性，但反射率受衬底温度的强烈影响。当在100℃的衬底温度下沉积LiF时，在1026 Å处获得最高反射率。讨论了老化对镜子反射率的影响。
