Grazing angle is used in samples that have a high reflectance, and where a small incidence angle can improve the measurement. JASCO has developed several grazing angle accessories for macro measurement. The Cassegrain Micro-GAR (RAS-500) employs a reflective Cassegrain mirror as shown in Fig. 1, enabling the measurement of large samples simply by placing a sample on the XY stage. A 16x reflective Cassegrain mirror is used to observe the measurement location, and then is switch into a Cassegrain Micro-GAR (RAS-500) for measurement.
Figure 2 shows an example of measurement of a thin film of poly methyl methacrylate (PMMA) film of 200 to 300 Å using a 0º polarizer (P polarization) and a 90º polarizer (S polarization).
Sensitivity is increased by using only parallel polarization on the plane of incidence.