Research On The Measurement Of VUV Spectral Transmission Characteristics

In recent years UV-VUV spectral remote sensing technology has become a research focus which draw international attention. It is of great significance to study the spectral transmission characteristics of optical components for improving the performance of optical remote sensing instruments. It is of obvious limitation when using commercial spectrophotometers currently used in many countries to test VUV transmission. It is very hard to measure the spherical mirrorreflectance, the hemispherical reflectance and the Bidirectional Reflectance-Distribution Function(BRDF) in the range of vacuum ultraviolet, which will seriously restrict the domestic development on Vacuum ultraviolet technology. Therefore, it is in urgent need to develop a high-performance vacuum UV transmission test system and to find a new Spectrometry Method to solve the problems mentioned above.The paper studies the test method of VUV transmission properties, designing a set of VUV transmission test system, and develops its test and research on the the spherical mirror reflectance, hemispherical reflectance and BRDF of the diffuser. The Spectral transmission test system takes Seya-Namioka monochromator as the spectral system, Modleâ…£Concave Grating of Jobin Yvon (JY) Co.France as the optical grating. The Modleâ…£Concave Grating, with 115nm-400nm wavelength range, 0.1nm Wavelength accuracy, and 0.05nm wavelength repeatability, is characterized by its simple structure and high efficiency of spectral transmission. The spectral reflectance Spherical mirror is measured in the following three ways, Double Beam Path Compensation method, integrating sphere detector and Fluorescence conversion film, which greatly weaken the impact on the test accuracy caused by light source instability, non-uniform detector response and poor signal to noise ratio. The results show that the uncertainty of spectral reflectance of the 115nm-180nm spherical mirror is 1.3%. A integrating Sphere is designed to test the vacuum ultraviolet hemispherical reflectance, by using the VUV transmission testing system to measure the hemispherical reflectance of the sample VUV hemisphere, finding out the sources of testing uncertainty and proposing the method of inhibiting and eliminating such uncertainty. The uncertainty of the measurement system is of 1.74%. For the diffuser, the studying of BRDF Testing Theory is carried out and a suitable method to test the BRDF of VUV diffuser is developed. The paper also develops the standard aluminum sample, which is suitable for vacuum ultraviolet, with normal incidence scattering Lambertian property.By testing the standard sample's hemispherical reflectance as its BRDF, the sample's BRDF can be obtained by comparing with that of the standard sample's. The sample's BRDF is tested in the wavelength range 160nm-200nm. The uncertainty of the test system is of about 2.03%.The above studies show that the test method of using the VUV transmission testing system to test the spherical mirror reflectance, hemispherical reflectance and bi-directional reflectance distribution function is accurate and effective, thus the study is of great scientific importance for further developing the VUV spectral remote sensing technology.