Thin slits: transmission and polarization

The paper discusses measurement of the transmission ratio T ||/T? of thin slits for light polarized linearly parallel and perpendicular to the slit direction at optical wavelengths and as a function of the angle of incidence. To obtain perfectly identical geometrical beams, the plane of polarization of the linearly polarized light is rotated in the measuring setup by means of plates of optically active quartz. The results indicate that the transmissivity is higher for light polarized parallel to the slit direction. This effect is more pronounced with narrow slits than with wide slits and, moreover, increases with the wavelength. For tangential orientation of the slit, the ratio T ||/T? increases with the angle of incidence. The paper studies the effect of surface reflections.