ISO 14490-5-2021 pdf download

ISO 14490-5-2021 pdf download.Optics and photonics一Test methods for telescopic systems一 Part 5: Test methods for transmittance. 5.2 Radiation source and condenser The radiation source shall emit a continuous flux of radiation in the specified wavelength range. The variation of flux during the measurement of a pair of values shall be less than I %. The condenser adapts the radiation source to the optical measurement path. It should be, for example, an achromatic doublet or an off-axis paraboloidal mirror to avoid introducing too much lateral chromatism into the optical ray path. 5.3 Monochromator or set of filters The monochromator or the set of filters can be omitted if the signal processing unit comprises a spectral detector. Grating or prism monochromators can be used to select the wavelength. The smallest adjustable wavelength interval shall be less than 2 % of the dominant wavelength (usually 0,55 i.im) of the respective measurement. The necessary spectral bandwidth depends on the sample. It should be ensured that a steep change in the transmission curve is detected correctly. Thus, the bandwidth should be selected such that the transmittance across the band changes by less than 4 %. This condition cannot always be satisfied because of technical measurement and energetical reasons or because the time/cost effort is not adequate. In these cases, a maximum bandwidth of 4% of the wavelength is allowable. A bandwidth of less than 2 % of the wavelength is necessary if the colour contribution indices are to be calculated. Instead of a monochromator, a set of narrow-band filters (full width half maximum