X射线单色器

可以考虑两种主要聚焦配置类型：

约翰几何（半聚焦）

通过以下两种方法其中之一获得薄板：

• 切割
• 机械加工

然后将薄板弯曲成圆柱形，并粘合到近似聚焦的曲面托架上。

约翰逊几何（精确聚焦几何）

考虑理论上可获得完美聚焦的两种不同类型约翰逊配置：

• 单机械加工约翰逊
• 双机械加工约翰逊

薄板要么弯曲成圆柱形，粘合到曲面托架上并对一面进行机械加工（单机械加工约翰逊），要么两面进行机械加工，然后粘合到曲面托架上（双机械加工约翰逊）。

圣戈班晶体将根据晶体类型选择最合适的技术，从而获得罗兰圆的尺寸和半径。 

其他类型的曲率可根据要求进行研究。可提供以下设计：

• 对数螺旋
• 椭圆
• 圆锥形
• 抛物线
• 球面
• 环形 

生产能力与晶体性质、尺寸以及曲率半径密切相关。 

Monochromating crystals

A monochromating crystal behaves in X-ray spectrometry as does a diffraction grating in optics. When rotated with respect to the incident polychromatic beam (see figure), it will diffract the spectral component along with direction to satisfy Bragg’s law, namely: 2d sin θ = n λ where integer n refers to the diffraction order. 

Hence, the most important characteristic of a monochromating crystal is the double atomic spacing 2d, which gives the largest wavelength to be diffracted.

The range of monochromators supplied can be found in Monochromator Crystal Properties along with the usual surface finish, within our control means, to the best intensity-resolution compromise. The optimum depends on each specific case and strongly reflects the nature of the set-up.

An X-ray spectrometer basically consists of:

An excitation source which may be either a primary X radiation, in which case one refers to X-ray fluorescence spectrometry. Or an electron beam, inducing a so-called direct emission, used in microprobes and scanning electron microscopes. 

A monochromating crystal which is used to disperse the various spectral components of the incident beam.

A detector in order to measure the intensity of the various spectral lines as singled out by the monochromator. 

The detector offered by Saint-Gobain Crystals combines a Nal(TI) or Lanthanum Bromide scintillator directly coupled to a photomultiplier with a low absorbing MIB or beryllium entrance window.