Goldberg and his former teacher and collaborator Robert Luther [ de ] were instrumental in the acceptance at the International Congress of Photography in Dresden in 1931 of the widely adopted German national film speed standard DIN 4512. At the same Congress Goldberg introduced his "Statistical Machine," a document search engine that used photoelectric cells and pattern recognition to search the metadata on rolls of microfilmed documents (US patent 1,838,389, 29 December 1931). This technology was used in a variant form in 1938 by Vannevar Bush in his "microfilm rapid selector," his "comparator" (for cryptanalysis), and was the technological basis for the imaginary Memex in Bush's influential 1945 essay "As we may think."