Abstract: The invention relates to a process for producing a porous glass and glass powder using a partial Vycor process on an alkali metal borosilicate glass material. The process is characterized in that an addition of metal oxides and/or rare earth metal oxides in variable proportions of from 0.05 to 15 percent by mass is carried out on the alkali metal borosilicate glass material during the course of the Vycor process, with a doping incorporation of the metal oxides and/or the rare earth metal oxides into the resulting SiO2 matrix with an increase in the optical index of refraction of the porous glass being brought about during the Vycor process, and an opposed jet milling process is employed in combination with a ceramic sifter wheel in a subsequent dry milling process, with classification of the porous glass particles produced which have a size range of less than 15 ?m being carried out.