| 摘要 |
PURPOSE:To easily obtain a desired transmittance step and dynamic range with a mn. number of filters by constituting a controller for quantity of light in such a manner that said controller can be independently inserted into an optical path and that said controller has the combination of n-pieces of filters having t, t<2>, -t<(n-1)> transmittances. CONSTITUTION:n-Pieces of the filters 1-1, 1-2, -1-n which can be independently inserted to the optical axis are disposed at optional intervals via a filter holding stand. The transmittances of n-pieces of the filters are designated at t, t, -t<2j(n01)> and the transmittances of the values obtd. by successively decreasing the basic transmittance t by the index of the power of 2 are provided to n-pieces of the filters. The controller which can continuously express w<n>-pieces of the integers of which the index is from zero up to 2<n-1> without excess or shortage from t<0> up to t<2n-1> is, therefore, effectively obtd. and the specified transmittance step is assured by preparing the filters of the transmittance series in which the transmittance step and transmittance dynamic range are thereby constituted with the min. filters.
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