Development of an Infrared Microscope for Three-dimensional Structural Study on Small Oritented Specimens

红外显微镜是新近发展起来的一种用于研究细小取向样品（如细小单晶、多晶样品的单畴和细长聚合物薄膜）的三维结构的显微镜。设计了一种由旋转台和椭球镜组成的红外聚光镜代替卡塞格林聚光镜，用于斜透射测量。利用该聚光器，可以将大部分入射辐射用于斜透射测量。效率是几倍高于使用卡塞格林冷凝器的测量。此外，该系统还可以任意选择入射方向，这对于样品取向变化困难的测量（如低温恒温测量）来说是非常方便的。为了调节入射辐射强度，采用了IR干涉滤光片。与通常使用狭缝或金属丝的调节相反，干涉滤光片通过所需频率范围的IR辐射。因此，红外光谱可以采取高强度的红外辐射，这使得信噪比高。通过网格，入射辐射直接照射样品，这大大减少了杂散光。

For the three-dimensional structural study on small oriented specimens, such as, fine single crystals, single domains of polycrystalline specimens and elongated polymer films, an infrared microscope has been newly developed. In stead of the Cassegr ain condenser, an IR condenser consisting of a rotary stage and an ellipsoidal mirror was designed for oblique transmission measurement. With this condenser, most of the incident radiation can be utilized for the oblique transmission measurement. The efficiency is several times higher than the measurement using an Cassegr ain condenser. Furthermore, any incident direction can be selected, which is quite convenient for the measurement where the orientation change of specimens is very difficult, for example, the measurement at a low temperature using a cryostat.For micro FTIR spectroscopy, prevention of the saturation of MCT detectors is important. For the adjustment of the incident radiation intensity, IR interference filters were employed. Contrary to usual adjustment using a slit or wiregauze, interference filters pass the IR radiation of desired frequency range. So the IR spectra can be taken with IR radiation of high intensity, which makes SN ratio high.Wire grids for electron microscopes were also adopted for holding specimens. Through the mesh, the incident radiation directly impinges the specimen, which greatly reduces stray light.