METHOD OF MEASURING DIFFERENCE IN COLOR CONTENT OF TWO SPECIMENS

摘要

PCT No. PCT/FI83/00049 Sec. 371 Date Feb. 3, 1984 Sec. 102(e) Date Feb. 3, 1984 PCT Filed Jun. 21, 1983 PCT Pub. No. WO84/00211 PCT Pub. Date Jan. 19, 1984.Method for the measurement of the difference in the color contents of two samples (1, 2) or of two component areas of a sample, in which method one or several sources of light (3 to 6) as well as one light detector (7) are used. According to the invention, both samples (1, 2), or component areas of a sample, are illuminated simultaneously and, from both samples (1, 2) or component areas of a sample, the light is passed simultaneously to the light detector (7). The lights to be measured from the samples (1, 2) or component areas of a sample are of different colors, as compared with each other, so that the light to be measured from the first sample or component area is absorbed weakly in the coloring agent and the light to be measured from the second sample or component area is absorbed strongly in the coloring agent. The colors of the lights to be measured from the samples (1, 2) or component areas of a sample are alternated with each other at an appropriate frequency, such as, e.g., at a frequency within the range of 1 c/s to 10,000 c/s. The AC signal given by the light detector (7) is used as the measure of the difference in the color contents of the samples (1, 2) or component areas of a sample.