Mini spectrometers employing back-thinned CCDs (S10420-1006-01 and S10420-1106-01) are approximately two orders of magnitude more sensitive than the same spectrometer using a PDA (S8381-512Q). However this same CCD achieves approximately one order of magnitude less signal-to-noise ratio when each detector is illuminated to 80% intensity. Therefore if enough light can be collected, the PDA produces a much higher signal-to-noise ratio and better linearity. If light levels are very low and the PDA shows little signal, then the CCD may be a better choice.

NMOS PDAs (N-channel or N-type metal-oxide-semiconductor field-effect transistors photodiode arrays), such as in the C9405MC spectrometer, are detector arrays holding the most charge and, therefore, producing the highest signal-to-noise levels. UV-type NMOS photodiode detector arrays have been relied on for decades and are commonly used in analytical UV-VIS systems.

Low cost BT-CCDs (back-thinned charge coupled devices) in the C9405CA spectrometer are relatively newer. Their higher overall sensitivity, at the expense of lower signal-to-noise ratio, opened array markets in fluorescence, emission, and Raman.

CMOS PDA (complementary metal-oxide-semiconductor field-effect transistors) technology as in the C9404MC spectrometer is maturing. It is least expensive to manufacture and has the flexibility to take on characteristics of an NMOS PDA or CCD. CMOS PDAs are used in absorbance spectroscopy and hold great promise in high-speed process monitoring.