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The troland (symbol Td), named after Leonard T. Troland, is a unit of ''conventional retinal illuminance''. It is meant as a method for correcting photometric measurements of luminance values impinging on the human eye by scaling them by the effective pupil size. It is equal to retinal illuminance produced by a surface whose luminance is one nit when the apparent area of the entrance pupil of the eye is 1 square millimeter.〔 (answers.com )〕 The troland typically refers to the ordinary or photopic troland, which is defined in terms of the photopic luminance: :, where ''L'' is the photopic luminance in cd m−2 and ''p'' is pupil area in mm2. A scotopic troland is also sometimes defined: :, where ''L′'' is the scotopic luminance in cd m−2 and ''p'' is pupil area in mm2. == Conversions to other units== 〔(wolframalpha.com ) 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Troland」の詳細全文を読む スポンサード リンク
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