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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Specific detectivity ： ウィキペディア英語版 Specific detectivity Specific detectivity, or ''D *'', for a photodetector is a figure of merit used to characterize performance, equal to the reciprocal of noise-equivalent power (NEP), normalized per square root of the sensor's area and frequency bandwidth (reciprocal of twice the integration time). Specific detectivity is given by $D^$ *=\frac, where $A$ is the area of the photosensitive region of the detector and $f$ is the frequency bandwidth. It is commonly expressed in ''Jones'' units ($cm\; \backslash cdot\; \backslash sqrt/\; W$)in honor of Robert Clark Jones who originally defined it.〔R. C. Jones, "Quantum efficiency of photoconductors," ''Proc. IRIS'' 2, 9 (1957)〕〔R. C. Jones, "Proposal of the detectivity D * * for detectors limited by radiation noise," ''J. Opt. Soc. Am.'' 50, 1058 (1960), )〕 Given that noise-equivalent power can be expressed as a function of the responsivity $\backslash mathfrak$ (in units of $A/W$ or $V/W$) and the noise spectral density $S\_n$ (in units of $A/Hz^$ or $V/Hz^$) as $NEP=\backslash frac\backslash cdot\backslash sqrt\}$. It is often useful to express the specific detectivity in terms of relative noise levels present in the device. A common expression is given below. $D^$ * = \frac \left(solid angle; this product is often called the etendue. This step can be obviated by the use of a calibrated source, where the exact number of photons/s/cm² is known at the detector. If this is unknown, it can be estimated using the black-body radiation equation, detector active area $A\_d$ and the etendue. This ultimately converts the outgoing radiance of the black body in W/sr/cm² of emitting area into one of W observed on the detector. The broad-band responsivity, is then just the signal weighted by this wattage. $R\; =\; \backslash frac\; =\; \backslash frac$ is the solid angle of the source projected along the line connecting it to the detector surface. From this metric noise-equivalent power can be computed by taking the noise level over the responsivity. $NEP\; =\; \backslash frac\; =\; \backslash frac\}H\; G$ Similarly, noise-equivalent irradiance can be computed using the responsivity in units of photons/s/W instead of in units of the signal. Now, the detectivity is simply the noise-equivalent power normalized to the bandwidth and detector area. $D^$ * = \frac = \frac \frac} 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「Specific detectivity」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.