PHOTODETECTION PART OF ILLUMINANCE METER

摘要

PURPOSE:To adjust spectral sensitivity finely and to easily obtain a standard relative luminosity factor by combining a luminosity factor correcting filter composed of three kinds of filters with two kinds of optical control filters whose transmitted light quantity can be controlled individually. CONSTITUTION:The photodetection part of an illuminance meter consists of a luminosity factor correcting filter 13 on a photoelectric converting element 14 and optical control filters 11 and 12. The correcting filter 13 is constituted by arranging three kinds of optical filters 13a-13c and 13d-13f regularly, the control filter 11 varies the quantities of transmission of the filters 13a-13c uniformly by a shield opening part 11a and an aperture part 11b, an the filter 12 varies the filters 13d and 13f without varying the quantity of light of the filter 13e. When the photodetection part is adjusted, the balance in the quantity of light between long wavelength and short wavelength is varied by the filter 12 and the filter 11 is rotated to vary the quantities of light uniformly. Consequently, the spectral sensitivity is adjusted finely and easily made coincident with the standard luminosity factor.