Measurement of optical density in a narrow wavelength band: a method for correcting the results of indirect measurements

The issues of correspondence of the results of direct and indirect measurements of optical density in a narrow wavelength band are considered. The optical density in a narrow wavelength band was measured by filtering the luminous flux according to the international standard ISO 5-3:2009 “Photography and graphic technology – Density measurements. Part 3: Spectral conditions” (direct measurement) and spectral method (indirect measurement). In order to ensure the uniformity of optical density measurements in a narrow wavelength band and establish the traceability of measurement results to the State Primary Standard of optical density units GET 206-2016, the degree of conformity of the results obtained by two methods was investigated. The techniques of measuring optical density in a narrow wavelength band for each method are described. The method of fi ltering the luminous flux was implemented using GET 206-2016, namely using a complex for measuring diffuse optical transmittance density. The Cary 7000 spectrophotometer (Agilent, USA) was used to implement the spectral method. Data on measuring the optical density of glass light fi lters by two methods are presented. A method for correcting the results of spectral measurements has been developed and a correction to the results of spectral measurements has been determined. The developed method and the correction make it possible to establish the correspondence of the results of spectral measurements to the results of measurements by fi ltering the luminous fl ux. Also, the described method for correcting the results of spectral measurements makes it possible to establish the traceability of the results of optical density measurements by the spectral method to the measurement results using GET 206-2016.