Description
An in-depth program of measurements of spectral characteristics and their derivatives from lighting engineering devices or any radiation sources is aimed at a detailed study of samples with a view to their design, refinement, modeling and development of optical systems, as well as determining the parameters of lighting devices (radiating devices) in terms of the dependence of their radiation spectrum (chromaticity coordinates, correlated color temperature, color rendering index, etc.) from the observation angle in the spatial distribution diagram luminous intensity (radiation power).
The use of LEDs in lighting devices, on the one hand, solves a number of their key tasks significantly more efficiently than lamps, but on the other hand, it has its own problems, the solution of which is based primarily on the precise definition (measurement) of the “technical picture” of these problems. Among the latter can be called one of the most common and typical for LED lighting devices of all types - a significant unevenness of chromaticity coordinates, correlated color temperature (CCT), shades of white depending on the angle of radiation. The manifestation of which is the "multicolored" spots of lightness of the surface: as a rule, from literally blue in the middle, and almost yellow - at the edges.
Although it is worth mentioning specifically about CCT and its interpretation in the proposed research program. The fact is that large-scale disputes about the methods of its determination in LEDs and in devices based on them did not lead to any constructive and unanimous opinion. Therefore, sometimes, the results of measurements of its values from the same sources may differ. As is known, the whole problem with this solution is based on the substantial non-uniformity of the spectral composition of the LED radiation, depending on the radiation angle. The main reason for this is the imperfection of methods for applying the phosphor coating, primary and secondary optics, as well as the existing unevenness of the flux density over the crystal area. On the one hand, it is obvious that possessing a narrow (1 degree) field of view, our eye cannot integrate the luminous flux not only from the whole but also from a small fraction of the spatial radiation pattern of the lighting device, so it is important that the indicated CCT value be the same throughout the diagram (otherwise it will not meet the specifications). But on the other hand, if it is the CTC that the total flow of the source is declared, then indeed, we can speak of the integral value of the CTC, regardless of its uneven distribution. In our opinion, the most equitable result of the reasoning about the correctness of the CCTT essence will be the condition under which the first situation characterizes the lighting fixtures, and the second - the light sources. Probably, thanks to this very interpretation of the “Solomon solution” about the measurement technique, since January 2016 there is no requirement in GOST R 54350-2015 for measuring the CCT by the integral method. This, in essence, significantly tightens the requirement for unevenness of CCT, since it can be measured at any point of the photometric body and must remain within the stated value, which is extremely difficult to ensure in most cases. But the meaning is much more correct and logical. This conclusion concerns the lighting devices, the standard for the measurement methods of which is given in the example; this also confirms previous assumptions about the interpretation of CCT. As a result, having detailed (provided by this Program) information on the spatial distribution of spectral (colorimetric) characteristics, it is possible to take into account the data obtained in the development of lighting devices or in the construction of the lighting system, thus avoiding the effect of “multicolored” illumination.
One of the important components of the set of the proposed research program for higher colorimetry is the ability to calculate and construct threshold McDam color difference ellipses in the equally contrasting MKO-31 colorimetric system for sources of any shades of white or quasi-monochrome emitters. This part can be useful in assessing the dispersion of the colorimetric characteristics of LEDs, on the basis of which the lighting device is built (assessment of the quality of binovka), the study of the luminescent properties of phosphors or in calculating the color difference thresholds in the study of the dependence of the spectrum on the radiation angle of a lamp with optical elements (street, industrial, focused lighting).
It should be noted that the Program provides for various studies and calculations based on high-precision measurements of the spectral distribution of radiation of samples in the range of 180 - 1100 nm (measurement step - 0.5 nm, measurement time of the entire range - 10 ms) using the Spekord installation (State Register of SI No.39537-08) and Flaks goniophotometric installation (State Register of SI No.39536-08 and No.39535-08). For example, visual or tabular representations of spect
