Nomogram for the Evaluation of Blackbody Radiancy and of Peak and Total Intensities

0= 85° onto a smooth surface, such as glass, possessed a high absorption characteristic of an aggregated structure (Fig. 4.), but diffuse reflection was not present. When, however, a film of 2.7,ug/cm 2 was deposited at 850 onto an aluminum film (16,ig/cm), which had been deposited at normal incidence, a strong decrease in specular reflectivity for the blue was obtained. Both aluminum films were deposited in sequence without atmospheric exposure of the first layer, and a small shield prevented the second coating from completely covering the mirror surface so that the reflectivity of both portions could be measured. The reflectivity of a typical film has been plotted in Fig. 5a and 5b. The mirror had a yellowish tinted specular reflection when viewed at normal incidence which changed to a white reflection when the viewing angle was increased. There was also a marked decrease in the normal reflectivity due to the high absorption of the obliquely deposited layer. A second experiment was made in which the surface roughness of the aluminum film deposited at normal incidence was increased by maintaining the glass substrate at 150° during evaporation, since Hass' has shown that aluminum films deposited at this temperature have increased grain size. The mirror was allowed to cool in vacuum and then coated obliquely with a second layer. As expected the specular reflectivity in the blue was greatly decreased. The latter results are not only useful in giving an insight into the mode of formation of films deposited at