be employed to replace or supplement the capillary feed as will be apparent the growth of different portions of the crystal dome is at different rates depending upon the distance of the growth surface from the center of curvature however the efg die surface 12d will control the thickness of the dome 14 over a large range of crystal growth rates the as grown dome will have a thickness variation of less than 10 often less than 2 since scattered light is an important feature of dome performance measurements were made both on two polished domes made in accordance with the present invention and on flat witness samples produced by the efg process the domes were measured on axis and in rings symmetric with the axis at 5 u00b0 10 u00b0 15 u00b0 and 20 u00b0 from the axis 61 points and the flat pieces at intervals of 0 080 34 out to a 0 32 increment radius from the center also 61 points at wavelengths of both 0 6326 um in the visible region of the spectrum and 3 39 um in the infrared region in every case the scatter increased away from the center of the piece results are given in table i in the case of the domes the scattered light was in the mid.