Abstract: An illumination device for a spectral optical measurement device includes arranged with respect to an optical axis of the illumination device which, during a measurement operation, extends along a normal to a center point of an area of a sample to be illuminated. One or more segments of a mirror in a shape of a ring are centered on the optical axis. The mirror has an internal reflective surface arranged such that, during the measurement operation, the internal reflective surface receives light emitted from the light source and reflects the light over the area of the sample to be illuminated. The internal reflective surface has a freeform shape in a cross-section through the internal reflective surface in a plane parallel to the optical axis (for example in which the optical axis lies), and, in a cross-section of the mirror in a plane perpendicular to the optical axis, the internal reflective surface is represented by a straight line.

Abstract: An illumination device for a spectral optical measurement device includes arranged with respect to an optical axis of the illumination device which, during a measurement operation, extends along a normal to a center point of an area of a sample to be illuminated. One or more segments of a mirror in a shape of a ring are centered on the optical axis. The mirror has an internal reflective surface arranged such that, during the measurement operation, the internal reflective surface receives light emitted from the light source and reflects the light over the area of the sample to be illuminated. The internal reflective surface has a freeform shape in a cross-section through the internal reflective surface in a plane parallel to the optical axis (for example in which the optical axis lies), and, in a cross-section of the mirror in a plane perpendicular to the optical axis, the internal reflective surface is represented by a straight line.

Abstract: A hand-held measurement device for appearance analyses includes a measurement array which comprises a number of illumination means for applying illumination light to a measurement field in at least three illumination directions and a number of pick-up means for capturing the measurement light in at least one observation direction. The illumination directions and the observation directions lie in a common system plane. At least one pick-up means is embodied to spectrally gauge the measurement light in a locally integral way, and at least one imaging pick-up means is embodied to gauge the measurement light in terms of color in a locally resolved way. The spectral pick-up means and the locally resolving pick-up means are arranged such that they receive the measurement light reflected by the measurement field under the same observation conditions and in particular from the same observation direction.

Abstract: A hand-held measurement device for appearance analyses includes a measurement array which comprises a number of illumination means for applying illumination light to a measurement field in at least three illumination directions and a number of pick-up means for capturing the measurement light in at least one observation direction. The illumination directions and the observation directions lie in a common system plane. At least one pick-up means is embodied to spectrally gauge the measurement light in a locally integral way, and at least one imaging pick-up means is embodied to gauge the measurement light in terms of colour in a locally resolved way. The spectral pick-up means and the locally resolving pick-up means are arranged such that they receive the measurement light reflected by the measurement field under the same observation conditions and in particular from the same observation direction.

Abstract: A hand-held measurement device for appearance analyzes includes a measurement array which comprises a number of illumination means for applying illumination light to a measurement field in at least three illumination directions and a number of pick-up means for capturing the measurement light in at least one observation direction. The illumination directions and the observation directions lie in a common system plane. At least one pick-up means is embodied to spectrally gauge the measurement light in a locally integral way, and at least one imaging pick-up means is embodied to gauge the measurement light in terms of color in a locally resolved way. The spectral pick-up means and the locally resolving pick-up means are arranged such that they receive the measurement light reflected by the measurement field under the same observation conditions and in particular from the same observation direction.

Abstract: A hand-held measurement device for appearance analyses includes a measurement array which comprises a number of illumination means for applying illumination light to a measurement field in at least three illumination directions and a number of pick-up means for capturing the measurement light in at least one observation direction. The illumination directions and the observation directions lie in a common system plane. At least one pick-up means is embodied to spectrally gauge the measurement light in a locally integral way, and at least one imaging pick-up means is embodied to gauge the measurement light in terms of colour in a locally resolved way. The spectral pick-up means and the locally resolving pick-up means are arranged such that they receive the measurement light reflected by the measurement field under the same observation conditions and in particular from the same observation direction.

Abstract: A hand-held measurement device for appearance analyses includes a measurement array which comprises a number of illumination means for applying illumination light to a measurement field in at least three illumination directions and a number of pick-up means for capturing the measurement light in at least one observation direction. The illumination directions and the observation directions lie in a common system plane. At least one pick-up means is embodied to spectrally gauge the measurement light in a locally integral way, and at least one imaging pick-up means is embodied to gauge the measurement light in terms of color in a locally resolved way. The spectral pick-up means and the locally resolving pick-up means are arranged such that they receive the measurement light reflected by the measurement field under the same observation conditions and in particular from the same observation direction.

Abstract: A hand-held measurement device for appearance analyses includes a measurement array which comprises a number of illumination means for applying illumination light to a measurement field in at least three illumination directions and a number of pick-up means for capturing the measurement light in at least one observation direction. The illumination directions and the observation directions lie in a common system plane. At least one pick-up means is embodied to spectrally gauge the measurement light in a locally integral way, and at least one imaging pick-up means is embodied to gauge the measurement light in terms of colour in a locally resolved way. The spectral pick-up means and the locally resolving pick-up means are arranged such that they receive the measurement light reflected by the measurement field under the same observation conditions and in particular from the same observation direction.

Abstract: A color measuring device includes a lighting arrangement for a measurement field of a measurement object to be measured, a pick-up arrangement for detecting the measurement light reflected back from the measurement field and for converting it into corresponding electric signals, an electronic circuit for controlling operation of the color measuring device and for processing and evaluating the electric signals, and a display for displaying measurement results. The lighting arrangement has a lamp ring with three identical lamp groups for illuminating the measurement field from a predefined range of angles of incidence. The pick-up arrangement has a digital camera which creates an image of the measured measurement field. The electronic circuit is designed to switch the light sources of the lamp groups on sequentially, and the camera creates a separate image of the measurement field for every switched-on light source.

Abstract: A color measuring device includes a lighting arrangement (10) for a measurement field (MF) of a measurement object (MO) to be measured, a pick-up arrangement (20) for detecting the measurement light reflected back from the measurement field and for converting it into corresponding electric signals, an electronic circuit (200) for controlling operation of the color measuring device and for processing and evaluating the electric signals, and a display (D) for displaying measurement results. The lighting arrangement (10) has a lamp ring (11) with three identical lamp groups (L1, L2, L3), mutually offset an angle of preferably 120°, each with, for example, 10 light sources (Ln) with different radiation characteristics in the form of light-emitting diodes for illuminating the measurement field (MF) from a predefined range of angles of incidence. The pick-up arrangement (20) has a digital camera (22) which creates an image of the measured measurement field (MF) made up of image pixels.

Abstract: Methods for measuring the colour of printed samples by measuring a first spectral proportion of the total spectral reflection factor of a sample by illuminating the sample with light having no UV element are provided. The methods calculate a spectral correction factor by making allowance for the characterisation data of the brightened substrate and the spectral properties of a selected type of illuminating light, adding the spectral correction factor to the first spectral proportion to obtain the total spectral reflection factor of the measured sample. The methods further evaluate the total spectral reflection factor on the basis of measurements taken with illuminating light with no UV element and with UV light only on a limited set of measurement samples, especially on the non-printed substrate only (paper whiteness).

Abstract: To measure the colour of samples printed on a substrate containing brightener, a first spectral proportion of the total spectral reflection factor of the sample is measured by illuminating the sample with light having no UV element. From this first spectral proportion, a spectral correction factor is calculated making allowance for the characterisation data of the brightened substrate and the spectral properties of a selected type of illuminating light. The spectral correction factor is added to the first spectral proportion in order to obtain the total spectral reflection factor of the measured sample. The total spectral reflection factor is then evaluated for measuring and control purposes, in particular for calculating colour values of the sample. The characterising data of the substrate is determined on the basis of measurements taken with illuminating light with no UV element and with UV light only on a limited set of measurement samples, especially on the non-printed substrate only (paper whiteness).

Abstract: For the color measurement of samples printed on a substrate including a brightener, a raw spectral reflection factor of the sample is measured in a first measurement by illumination of the sample with light without UV portion. In a second measurement, a fluorescence spectrum of the sample is measured by illumination of the sample with only UV light. The measured fluorescence spectrum is recalculated as a corrected fluorescence spectrum by weighting with spectrally dependent correction factors and, finally, the measured raw spectral reflection factor and the corrected fluorescence spectrum are added to form a corrected spectral reflection factor from which the values characterizing the color of the sample are then calculated. The spectral correction factors are determined during the device manufacture for a certain set of light types and stored in the device.

Abstract: For the colour measurement of samples printed on a substrate including a brightener, a raw spectral reflection factor of the sample is measured in a first measurement by illumination of the sample with light without UV portion. In a second measurement, a fluorescence spectrum of the sample is measured by illumination of the sample with only UV light. The measured fluorescence spectrum is recalculated as a corrected fluorescence spectrum by weighting with spectrally dependent correction factors and, finally, the measured raw spectral reflection factor and the corrected fluorescence spectrum are added to form a corrected spectral reflection factor from which the values characterizing the colour of the sample are then calculated. The spectral correction factors are determined during the device manufacture for a certain set of light types and stored in the device.