软X射线波段透射光栅衍射效率检测系统

为获得透射光栅在软X射线波段的各级衍射效率,利用凹面反射光栅单色仪加激光等离子体光源组成一套软X射线波段单色系统,并以He空心阴极光源所发射的30.38、53.70、58.43nm三条谱线做为标准点,通过建立拟合曲线方程的方法对该单色系统进行波长标定。然后以背照射CCD(charge-coupled device)做为接收元件,对金自支撑式透射光栅在85～900eV能区范围内的多个能量点进行了衍射效率的实验标定,获得了该透射光栅一级相对衍射效率和零级绝对衍射效率的标定结果。同时利用准梯形栅线模型对该透射光栅在软X射线波段范围内的衍射效率进行理论计算,得到了该透射光栅一级相对衍射效率的理论曲线,模型计算结果与实验标定结果基本符合。最后,利用实验中得到的零级绝对衍射效率和模型计算的一级相对衍射效率结果拟合出了该透射光栅一级绝对衍射效率曲线。

Measuring system for diffraction efficiency of transmission grating in soft X-ray

In order to get the absolute diffraction efficiency of transmission gratings,a soft X-ray monochromatic system is built up.The system is composed of a concave reflective grating monochromator and a laser plasma source.Three spectral lines of 30.38 nm,53.70 nm and 58.43 nm from Helium hollow cathode source are used to calibrate the wavelength of the transmission grating measuring system.A black illumination Charge-Couple Device(CCD) is used as reception element to experimentally calibrate the diffraction efficiency of a golden self-supporting transmission grating at several energy points between 85 and 900 eV.The calibration results for the first-order relative efficiency and zero-order absolute efficiency are obtained.The diffraction efficiency of this grating in soft X-ray band is simulated using quasi trapezoidal grating line model.The simulated first-order relative diffraction efficiency is basically consistent with experimental calibration.Finally,the measured zero-order absolute efficiency and simulated first-order relative efficiency are used to fit the curve of the first-order absolute efficiency of the grating.