Detail of GB/T 44268.2-2024

Introduction of GB/T 44268.2-2024

GB/T 44268.2-2024 Microscopes - Definition and measurement of illumination properties - Part 2： Illumination properties related to the colour in bright field microscopy 1 Scope This document specifies measurands and measurement procedures of colour properties for bright field microscopy with transmitted light illumination. These measurements are defined in image planes or intermediate image planes. This document also specifies how the information is provided to the user. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 11664-1:2019 Colorimetry - Part 1: CIE standard colorimetric observers ISO 11664-3 Colorimetry - Part 3: CIE tristimulus values 3 Terms and definitions No terms and definitions are listed in this document. ISO and IEC maintain terminological databases for use in standardization at the following addresses: ——ISO Online browsing platform: available at http://www.iso.org/obp ——IEC Electropedia: available at http://www.electropedia.org/ 4 Measurands 4.1 General Since various light sources such as halogen lamps, tungsten lamps, LEDs, and OLEDs are used for bright field microscopy, it is essential to understand the difference in colour properties due to the light sources. This applies for different applications and various types of instruments. 4.2 Spectral measurement The spectral radiant flux (W) shall be measured by placing an instrument equipped with an integrating sphere and an optical spectrometer function in an image plane or in an intermediate image plane. The measurements shall be performed in the measurement spectral range from 380 nm to 780 nm with 5 nm intervals or less. 4.3 Chromaticity The chromaticity coordinates (x, y) shall be calculated from the measured spectral properties by calculating the tristimulus values of the XYZ colour space (CIE 1931 colour space) by using the CIE 1931 2° colour-matching functions. The tristimulus values X, Y and Z shall be defined according to ISO 11664-1 and ISO 11664-3 by the following Formulae (1) to (3): The constant k is defined as follows: The chromaticity coordinates x and y are calculated from the tristimulus values X, Y, Z as given in Formulae (5) and (6): The diagram produced by plotting x as abscissa and y as ordinate is defined as the CIE (x, y) chromaticity diagram. An example is given in Figure 1. According to ISO 11664-1 and ISO 11664-3, it is sufficient to use the values of colour-matching functions in the spectral range from 380 nm to 780 nm with 5 nm intervals in this document. Therefore, if the measurement of the spectral radiant flux is performed with an interval of less than 5 nm, the measured data shall be converted to 5 nm intervals by either using the least squares method or the data shall be extracted by 5 nm intervals only. Note: There are two types of colour-matching functions defined according ISO 11664-1, the CIE 1931 2° colour-matching functions and the CIE 1964 10° colour-matching functions. This document applies only the CIE 1931 2° colour matching functions which have been used in general. 4.4 Correlated colour temperature, Tcp 4.4.1 General Although there are various methods available, for calculating the correlated colour temperature according to this document either the method described in 4.4.2 or 4.4.3 shall be used. The colour temperature is an index to express the colour by a single parameter when the chromaticity of the light source is on the black body locus. However, actual light sources do not completely match with the black body radiation. Therefore, the correlated colour temperature, i.e. the colour temperature of the nearest colour on the black body locus shall be used. 4.4.2 Correlated colour temperature using the CIE 1960 UCS chromaticity diagram and its procedure The tristimulus values of the XYZ colour space (CIE 1931 colour space), calculated from the spectral properties obtained by the spectral measurements and the CIE 1931 2° colour-matching functions according to 4.3 shall be converted to (u, v) chromaticity values on the CIE 1960 UCS chromaticity diagram. The (u, v) chromaticity values are calculated by the following Formulae using the tristimulus values X, Y and Z[4]. Afterwards, the correlated colour temperature shall be expressed as an absolute temperature which corresponds to the nearest point on the black body locus from the (u, v) chromaticity values in the diagram[4]. The correlated colour temperature shall only be indicated if the distance from the black body locus is ± 0.05 or less in the (u, v) chromaticity diagram[4]. 4.4.3 Correlated colour temperature using (x, y) chromaticity coordinates The correlated colour temperature shall be obtained by Formula (9) proposed by McCamy[6]. Where, n is defined as follows using the (x, y) chromaticity coordinates (according to 4.3) according to formula (10): The error caused by this approximation is regarded as negligible for practical use.

Contents of GB/T 44268.2-2024