Abstract:
A spectral photoelectric measurement transformer comprises an array (10) of photoelectric transformer elements and dielectric interference bandpass filters (22a, 22b) disposed on a common filter support (21) connected upstream of them for sensitizing the transformer elements to different wavelength ranges of the measurement light. The bandpass filters are divided into a number of filter groups, each of which contains the same different bandpass filters within the filter group. An optical deflector element (30) spectrally shifts the effective bandpass curves of the bandpass filters of all the filter groups except one so that the effective bandpass curves of all the bandpass filters have different spectral positions. As a result, a multiplication of the filter channels effectively made available can be achieved using only a few different bandpass filters. Due to the small number of different bandpass filters, the measurement transformer is inexpensive to manufacture.
Abstract:
In a method for determining color and/or density values for use in monitoring and regulating a printing process in a printing apparatus, specifically in a sheet-fed offset printing press, measuring areas of a printed sheet are measured photoelectrically during the printing process, directly in or on the running printing apparatus. From the measured values obtained in the process, the color and/or density values for the relevant measuring areas are formed. From the measurement, measured value deviations caused directly in the printing process with respect to a measurement outside the printing process can be corrected computationally.
Abstract:
A phase mask (15) for modulating a collimated light beam passing therethrough, the light beam being diffracted to photoinduce a refractive index profile in a photosensitive optical medium, the phase mask (15) comprises a substrate (17) having an outer surface provided with a plurality of parallel grating corrugations (19). The grating corrugations (19) have a non-uniform relief depth across the outer surface for photoinducing a non-uniform refractive index profile in the photosensitive optical medium. The non-uniform relief depth is defined by a variable thin film layer (21) of variable thickness overlaying the substrate (17). The grating corrugations (19) can either be etched into the variable thin film layer (21) itself or be etched into the substrate (17), with the variable this film layer (21) being deposited on it after etching. Methods to make such phase masks are also provided.