Estimation of the power needed to be generated by QDs in the focal plane (A). The noise equivalent power (NEP) for the detector is scaled by the peak width of the QDs, the collection angle, and the system components. A clear minimum is observable in the ∼900 nm wavelength emission peak range. Using the measured absorbance to estimate the absorption cross section then allows the minimum laser power needed to achieve NEP on a single QD (note: in practice this is limited by blinking) at a range of laser wavelengths, and it is observed that there is a power minimum at the 600–700 nm wavelength range (B), for which a 660 nm laser line was chosen. When the power limitations of our excitation source is included, the system response to a range of QD concentrations is able to be estimated (C).