United States Patent 3504457
Inventors:
Jacobsen, Hans R.
Jensen, Elmer W.
Publication Date:
04/07/1970
Assignee:
GEOSCIENCE INSTR CORP
Other Classes:
451/533, 257/E21.237
International Classes:
B24B37/04; B24D7/02; H01L21/304; B24D7/00; H01L21/02; B24B29/00; B24B11/00; B24B5/00