On the Determination of the Relative Phase Change at Reflection Air–Metal and Its Variation with Thickness for Silver Layers

Abstract

Silver layers of different thickness ranging from 30 to 200 A were evaporated on glass substrate. The phase change at reflection air–Ag was determined using a Koster interference comparator for He λ5875 A. A compensating silver layer was found at which the fringe shift due to the phase change at reflection from the air–Ag interface was equal and opposite in direction to that due to the thickness of the metallic layer. Its thickness ranged from 60–70 A. In the case of evaporated copper layers on glass substrate, the thickness of the compensating layer ranged from 80 to 90 A for λ5875 A. Using the compensating layer as a component in a wedge interferometer altered the intensity distribution in the multiple-beam reflected system to resemble that of a transmitted system.