Abstract: A light-weight yet sturdy ceramic article, is manufactured by initially forming at least one fugitive core including a main portion and at least one holding portion projecting from the main portion and then positioning the fugitive core in a mold cavity bounded by a multitude of bounding surfaces so that the holding portion holds the main portion at predetermined spacings from all of the bounding surfaces. This is followed by filling the mold cavity around the fugitive core with a dense slip constituted by ceramic or metal particles in mixture with a liquid medium to form a ceramic or metal preform embedding the fugitive core in its interior and freezing the ceramic or metal preform, then the fugitive core is dissolved and escapes from the interior of the frozen ceramic or metal preform and finally the ceramic preform is converted into the ceramic article.

Abstract: An optical component having a plurality of cooling channels in a surface region underlying its effective surface is manufactured by first forming a precursor of the optical component consisting of a main body which carries the effective surface, and a plurality of solid fugitive material cores embedded in the main body at the desired locations of the cooling channels, and then converting the precursor into at least a portion of the optical component by consolidating the main body, and removing the cores from the cooling channels, such as by melting the fugitive material of the cores.