The spectral output quantity of a system such as a photomultiplier, diode array, @I02944@ device, or biological unit divided by the @S05817@ \(s(\lambda) = \frac{\text{d}y\left(\lambda \right)}{\text{d}E\left(\lambda \right)}\), simplified expression: \(s(\lambda) = \frac{Y_{\lambda }}{E_{\lambda }}\), where \(Y_{\lambda }\) is the magnitude of the output signal for @I03255@ at @W06659@ \(\lambda \) and \(E_{\lambda }\) is the @S05817@ of the parallel and perpendicular incident beam at the same @W06659@.