Silicon nitride, prepared by the chemical vapor deposition (CVD) method, transmits electromagnetic energy in the visible, infrared and radar frequency ranges. In this paper, the visible and infrared transmittance properties of polished flat plate and hemispherical shell geometries are described. Integrating sphere hemispherical and in-line specular transmittance measurements indicate near intrinsic levels are being achieved in the infrared wavelength region, however, a diffuse scattering component is limiting imaging capability. Current processing research is aimed at identifying deposition conditions which will eliminate major scattering sources such as the microcrack network found in all deposits made to date. Achievement of this research goal will broaden the optical applications of this unique refractory ceramic.