由于可有效降低高热负载的影响,Laue弯晶是插入件辐射高通量密度硬X射线(30keV以上)聚焦、准直和单色化的最有效的光学元件.研究其聚焦光学特性,对发展高性能、高稳定的Laue弯晶单色器具有重要意义.采用自行发展的光线追迹软件较为系统地研究了Laue弯晶的聚焦特性,分析了入射光性质及弯晶参数对聚焦光斑、焦距、发散度等主要光学参数的影响.结果表明,衍射能量越高,聚焦光斑越小,并趋于稳定值;弯曲半径越小,聚焦光斑越小,并在其达到一阈值时得到聚焦光斑的极小值,之后随着弯曲半径的变小,由于像差等因素的影响,聚焦光斑反而变大;晶体越厚,聚焦光斑越大,呈线性正比关系.对于衍射光发散度,其随着衍射能量的增大而变小,并趋于稳定值;其与晶体曲率呈线性正比关系.同时通过研究得到弯晶各参数的合理选择范围.
The lane bent crystal is the most effective optical element of focusing, collimating and monochromating of high flux density hard X-rays (above 30 keV) from the insertion device radiation, because of reducing the high heat load effectively. So the study of the focusing optical properties is important for developing high performance and stability lane bent crystal monochromator. We give a systematic research of the focusing properties of laue bent crystal by X-ray trace program self-developed, analyze the effects of the mode of incident beam and crystal parameter on focusing spot size, focal length, diffracted beam divergence, etc., and obtain the following results: the higher the diffracted energy, the smaller the spot size is and the spot size tends to be a constant; the smaller the bend radius of crystal, the smaller the spot size is, and the spot size reaches a minimum when the bend radius is a threshold, then as the bend radius decreases, the spot size becomes larger because of aberration; the spot size is linearly directly proportional to the thickness of crystal. For the divergence of diffracted beam, it becomes smaller as the diffracted energy is high, and tends to be a constant; it is linearly directly proportional to the curvature of bent crystal. Also we obtain a reasonable range of bent crystal parameters from the study by ray-tracing.