单色器晶体角度微振动的高精度原位检测技术

High-accuracy in-situ detection method of monochromator angular vibration

为实现对双晶单色器角度微振动的原位测量,设计了基于双频激光干涉仪的双晶单色器晶体角度微振动测试系统,并搭建了实验平台。激光经干涉计偏振分光后射向被测晶面,对反射信号调制解调求得晶面两端的位移偏差,从而高频获取晶面的角度位移信息。通过数据预处理可以有效去除夹杂在数据中的噪声及直流分量,应用快速傅立叶变换处理得到晶体角度振动的频谱信息,准确获取对晶体稳定性产生影响的特征频率,从而分析影响晶体稳定性的主要振源。该方案可实现晶体角位移的高频采集,分辨率高达25 nrad,并能准确分析出不同振源影响下晶体微振动的情况,为单色器结构优化提供参考。

In order to achieve in-situ measurement of Double-Crystal Monochromator(DCM)stability,an angular vibration measuring system based on dual-frequency interferometers is designed,and a measurement platform is also established.A laser is split into two beams with an interferometer and then is aimed at the crystal surface.Reflective signals from both ends of the crystal are demodulated by a data acquisition board and the crystals′angular displacement information is acquired at high frequency.Its frequency information can also be obtained by means of Fast Fourier Transform(FFT),from which the primary source of vibration that influences the stability of the monochromator can be deduced.We can achieve high-frequency acquisition of crystal angular displacement with a resolution of up to 25nrad.With this,information on the different sources of vibration can be distinguished,which can be significant in DCM structure optimization.