Determination of chromatic aberration of prepainted steel coils

The principle of color difference measurement is to determine the color difference between reference sample and reference sample quantitatively by measuring the spectral tri-stimulus value of reference sample and sample.

The geometric structure of chromatic aberration meter can be divided into directional type and integral sphere type.

The directional geometric structure can be divided into two types: 45°/0° and 0°/45°.

And 0° over 45° means that the light is shining vertically and the sample is receiving reflected light at 45°.

The instruments of these two structures do not include mirror reflection light at all, and the data it measures are consistent with the observation of the human eye. In addition, such instruments can only measure the color of opaque samples.

The integrated spherical geometric structure can be divided into two types: d/8° and 8°/d. The instrument of the integrated spherical structure is to illuminate the sample horizontally, while the detector receives reflected or transmitted light in the direction of 8° from the sample. This instrument can not only measure the color of opaque samples but also the color of transparent samples.

 

When measuring, choose standard light source, standard chroma observer, color space and observation aperture.

The chromaticity coordinates of the reference samples, CIELAB L*, a*, b* or HunterLab L, a, b, were measured under the selected instrumental conditions, and then the chromaticity coordinates of the three different parts of the sample were measured under the same conditions.

If the directional chromatic aberration meter is not illuminated by a ring, the same measuring point of the reference sample and sample should be rotated 90° according to four directions, and the four chromaticity coordinate values should be measured. The arithmetic mean value is the chromaticity coordinate value of the measuring point.