祥子
第2楼2009/02/27
Cross Dispers造成的光能损失非常大,紫外损失32%,可见光损失84%
,散射损失这么多,不大可能。
在Czerny Turner in UV和Czerny Turner in VIS中这项为零,在Echelle in UV和Echelle in VIS都是1,它这个表的项是怎么这么分。
为什么把Echelle单独列出来,一般该包含在Czerny Turner这种光路中的啊,我可能理解错了。
祥子
第7楼2009/02/28
我在网上查到一个解释:
Cross-Disperser Unit
Cross-dispersion is used to separate the the echelle orders on the detector. For bHROS, the cross-dispersion is provided by a set of 60o fused silica prisms. This method was chosen because prism cross-dispersion is about a factor of two more efficient than grating cross-dispersion (owing to the absence of parasitic orders) and also conveys a number of other advantages (i.e. being virtually stray light free and providing more uniform order separation).
The cross-dispersion system provides a minimum order separation of 3.00 mm in the camera focal plane. This separation provides sufficient inter-order spacing for (1) adjacent sky and object spectra in dual-fiber mode or (2) one broad object spectrum in single-fiber mode. The minimum order separation occurs at a wavelength of approximately 780 nm, with the order separation being larger than this at longer and shorter wavelengths.
这么看好像是某种色散元件。
因为在一个资料上说,中阶梯(echelle)光栅光谱仪采用二维色散技术,先用一个低色散的光栅或棱镜在垂直于中阶梯光栅方向将各级次光谱色散开(谱级色散),再用一个中阶梯光栅在水平方向将同一级次光谱按波长色散开(谱线色散),从而获得二维色散光谱图。
所以,Cross-Dispers该是上面说的谱级色散元件了,为了将各级光谱色散开,如上面所说,Cross-dispersion is used to separate the the echelle orders on the detector。
如下图
std.grating 就是cross dispers