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

The article considers the correspondence between the results of direct and indirect optical density measurements in a narrow wavelength band. The optical density in a narrow wavelength band was measured via luminous flux filtering (direct measurement) as per ISO 5‑3:2009 Photography and Graphic Technology—Density Measurements. Part 3: Spectral Conditions and via the spectral method (indirect measurement). In order to ensure the uniformity of optical density measurements in a narrow wavelength band and to establish measurement traceability to GET 206-2016 State primary optical density standard, the degree of correspondence between the results obtained via the two methods was analyzed. The authors describe procedures for measuring optical density in a narrow wavelength band for each method. The luminous flux filtering was implemented by means of GET 206-2016, specifically with the use of a system for measuring diffuse transmittance density. The spectral method was realized using a Cary 7000 spectrophotometer (Agilent, USA). Data on measuring the optical density of optical glass filters via the two methods are presented. A method was developed for correcting spectral measurement results and a correction to the results of spectral measurements was determined. The developed method and obtained correction help to establish the correspondence between the results of spectral measurements and measurements via luminous flux filtering. In addition, the described correction method provides a means to establish the traceability of optical density measurement results obtained via the spectral method to those obtained using GET 206-2016.