Dynamic range (DR)
refers to the range in which a detector is capable of accurately
measuring the signal increment above the noise level. The DR is
the saturation charge (full well capacity) divided by the noise.
Refer to the previous discussion on different noises encountered
in different venders’ DR definitions.
For Si based array detectors, a
non-scientific front-illuminated CCD (such as Sony ILX511) has a
low readout noise and a small well capacity. Thus it has a small
dynamic range and is good for use in non-demanding applications
where weak signals are measured and low cost is the key. The BT
CCDs are scientific grade devices that exhibit low readout
noise, low dark current, and a large well capacity. They provide
large DRs and are ideal for weak signal detection where high
measurement SNRs are required. The PDA has inherently high
readout noise, high dark current, and a very large well
capacity. Hence it achieves a high DR as well but is more suited
for high light level detection applications where high SNR is
essential for differentiating small differences. For near
infrared (NIR) array detectors, the standard InGaAs array has
better dynamic range compared with extended InGaAs or PbS arrays
in 900-1700 nm. The PbS and the extended InGaAs arrays have
comparable dynamic ranges in their corresponding spectral
response regions.
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