Abstract: Process for measuring the optical properties of thin layers while they are being built up in vacuum coating installations. For this purpose, at least one test object is passed through a stationary measuring light beam and the transmission behavior of the test object is evaluated by measurement. A reference point for the measurements is fixed in each case by reference measurements at intervals of time. In addition, at least one opaque measurement zone and at least one measuring zone, which does not attenuate the measuring light beam, are disposed in path of motion of the test object. The ratio of the measured value of the test object, decreased by the measured value of the opaque measuring zone, to the measured value of the nonattenuating measuring zone, decreased by the measured value of the opaque measuring zone, is formed by an arithmetic logic unit.

Abstract: An arrangement for measuring and controlling the thickness of optically transparent coatings during their build-up on substrates in vacuum coating installations. The measurement is carried out by determining at least one reference value and at least one measured value for the transmission or reflection value of the coated object by using a measuring light beam, a monochromator, a photo-receiver, an amplifier and an analyzing circuit.

Abstract: An arrangement and photometer for measuring and controlling the thickness of optically active thin layers wherein the axis of the measurement light beam coming from the measurement light source is directed to the measurement object and a referenced light receiver, independent of the optical properties of the measurement object, is associated with the measurement light beam. The output signal of the referenced light receiver is mixed with a trigger stage for a phase sensitive photometer amplifier and is fed to a compensation circuit for the equilization of brightness variations in the measurement light source.