Increasing the Measurement Accuracy of Wide-aperture Photometer Based on Digital Camera

Authors P.І. Neyezhmakov1, О.М. Lyashenko2, E.P. Tymofeiev1, О.D. Kupko1, А.S. Litvinenko2

1 National Scientific Centre “Institute of Metrology”, 42, Myronosytska St., 61002 Kharkiv, Ukraine

2 O.M. Beketov National University of Urban Economy, 17, Marshala Bazhanova St., 61002 Kharkiv, Ukraine

Issue Volume 11, Year 2019, Number 3
Dates Received 13 February 2019; revised manuscript received 10 June 2019; published online 25 June 2019
Citation P.І. Neyezhmakov, О.М. Lyashenko, E.P. Tymofeiev, et al., J. Nano- Electron. Phys. 11 No 3, 03029 (2019)
PACS Number(s) 07.60.Dq, 07.60.Vg
Keywords Photometer (2) , Luminous flux, Spectral responsivity of the receiver, Digital camera.

To reduce the cost and time of testing the lighting characteristics of LED sources, a photometer design based on a fiber-optic focon has been proposed and patented for measuring the spatial distribution of radiation without rotation. The results of studies of the spectral characteristics of the digital cameras with ССD-matrices included in this wide-aperture photometer as a photodetector matrix have been presented in the paper. The spectral characteristics of the matrix photodetectors have been investigated in accordance with the procedure of CIE standardization (ISO/СIE 19476:2014). The deviation of the obtained spectral characteristics from the standard function of the relative spectral luminous efficiency of monochromatic radiation for photopic vision V(() has determined the measurement error of the photometric body of light devices. It was established that measurement of the spectral characteristics of digital camera matrices only on the “green channel” is not sufficient, since the mismatch between the measurement result and the function of relative spectral luminous efficiency of monochromatic radiation for photopic vision is in the range from 6 % to 22.5 %. Based on the range of color temperatures of the sources of visible radiation, which are mainly used for illumination, the error estimate of the proposed photometer was performed for thirteen LED light sources with typical spectral characteristics that most fully cover the spectrum of light sources on the market in terms of the range of correlated color temperatures ТС: 2700-8400 K. To ensure the specified accuracy of photometers by correcting the spectral responsivity characteristic Srel(() of digital camera, a correction optical filter with the corresponding characteristics is used. As an optical filter, it is proposed to use a combination of three-color optical filters ZS 8, SZS 24 and ZhZS 18. The spectral transmission characteristics of the optical filter are determined by the combined use of these three glass grades, the thickness of each is selected separately. It is shown that with the use of the developed correction filter, which is a combination of 3 types of glass, it is possible to reduce the error of spectral measurements to 5 %.

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