Abstract: To produce a standard calibration and test element for the calibration and testing of reading and measuring instruments for bar codes and other test scales, a copper coating is applied to a ceramic substrate in a chemically depositing copper bath and degreased, and a photoresist coating is subsequently applied which is exposed through an exposure mask. This mask carries an image of the radiation-transparent and radiation-opaque regions of a pattern to be transferred onto the surface of the ceramic substrate. After removal of the mask, the photoresist coating is developed, the uncovered zones of the copper coating are etched in a metal chloride solution, and the remaining photoresist coating is removed by stripping. The uncovered, etched zones of the copper coating are dyed matt black in a metal bath. Finally, the conductive tracks are provided with a protective coating.

Abstract: This invention relates to a control device, suitable for use to control the exposure of a light-sensitive material in a copying apparatus for the preparation of a printing plate, which comprises program store means for predetermining a basic exposure, input line means for connection to a photocell for measuring the luminous intensity of a light source in the copying apparatus, comparator means having its input connected to an output of the program store means and connected by a transmission path means to the input line means, the output of the comparator means being connectable to a control switch for the light source, and the transmission characteristics of the path being variable in steps, adjacent pairs of which have transmissivities in the ratio .sqroot.2:1.