Homes C C, Reedyk M, Cradles D A, Timusk T
Appl Opt. 1993 Jun 1;32(16):2976-83. doi: 10.1364/AO.32.002976.
Details are given of a technique for measuring the reflectance at near-normal incidence of small, irregular, submillimeter-sized samples from the far IR (40 cm(-1)) to the visible (40000 cm(-1)) between 10 and 300 K by using a modified Michelson interferometer or grating spectrometer. The sample and a reference mirror are mounted on nonreflecting cones. At the focus the size of the beam is larger than either the sample or the reference, so that the entire area of the sample is utilized. The positions are interchanged by a 90° rotation by using preset mechanical stops. The scattering caused by geometrical effects is corrected for by the in situ evaporation of gold or aluminum onto the sample. The effect of diffraction is estimated from Mie theory by assuming the sample and reference to be spheres. For frequencies above ≈ 40 cm(-1) and sample diameters of ≈ 1 mm with a detector field of view of 30°, the calculations show that the ratio of the backscattered intensities gives a good approximation of the specular reflectance.
介绍了一种通过使用改进的迈克尔逊干涉仪或光栅光谱仪，在10至300 K温度范围内测量远红外（40 cm⁻¹）至可见光（40000 cm⁻¹）波段、尺寸小于1毫米的小尺寸不规则样品近正入射反射率的技术。样品和参考镜安装在非反射锥上。在焦点处，光束尺寸大于样品或参考镜，从而可利用样品的整个区域。通过使用预设的机械挡块，通过90°旋转来互换位置。通过在样品上原位蒸发金或铝来校正几何效应引起的散射。通过假设样品和参考镜为球体，根据米氏理论估算衍射效应。对于频率高于≈40 cm⁻¹且样品直径约为1毫米、探测器视场为30°的情况，计算表明后向散射强度之比能很好地近似镜面反射率。
