Acronyms that contain the term specific detectivity 

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 ∗ = A Δ f N E P {\displaystyle D^{*}={\frac {\sqrt {A\Delta f}}{NEP}}} , where A {\displaystyle A} is the area of the photosensitive region of the detector, Δ f {\displaystyle \Delta f} is the bandwidth, and NEP the noise equivalent power in units [W]. It is commonly expressed in Jones units ( c m ⋅ H z / W {\displaystyle cm\cdot {\sqrt {Hz}}/W} ) in honor of Robert Clark Jones who originally defined it.Given that noise-equivalent power can be expressed as a function of the responsivity R {\displaystyle {\mathfrak {R}}} (in units of A / W {\displaystyle A/W} or V / W {\displaystyle V/W} ) and the noise spectral density S n {\displaystyle S_{n}} (in units of A / H z 1 / 2 {\displaystyle A/Hz^{1/2}} or V / H z 1 / 2 {\displaystyle V/Hz^{1/2}} ) as N E P = S n R {\displaystyle NEP={\frac {S_{n}}{\mathfrak {R}}}} , it is common to see the specific detectivity expressed as D ∗ = R ⋅ A S n {\displaystyle D^{*}={\frac {{\mathfrak {R}}\cdot {\sqrt {A}}}{S_{n}}}} . 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 ∗ = q λ η h c [ 4 k T R 0 A + 2 q 2 η Φ b ] − 1 / 2 {\displaystyle D^{*}={\frac {q\lambda \eta }{hc}}\left[{\frac {4kT}{R_{0}A}}+2q^{2}\eta \Phi _{b}\right]^{-1/2}} With q as the electronic charge, λ {\displaystyle \lambda } is the wavelength of interest, h is Planck's constant, c is the speed of light, k is Boltzmann's constant, T is the temperature of the detector, R 0 A {\displaystyle R_{0}A} is the zero-bias dynamic resistance area product (often measured experimentally, but also expressible in noise level assumptions), η {\displaystyle \eta } is the quantum efficiency of the device, and Φ b {\displaystyle \Phi _{b}} is the total flux of the source (often a blackbody) in photons/sec/cm².

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