Ocean Optics Flame-S, User Manual

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6: Technical Specifications
54 225-00000-000-11-201604
Spatial averaging or pixel boxcar averaging can be used to improve S:N when observed spectral
structures are broad. The traditional boxcar algorithm averages
n
pixel values on each side of a
given pixel.
Time-based and spatial-based algorithms are not correlated, so therefore the improvement in
S:N is the product of the two processes.
In review, large-well devices are far less sensitive than small-well devices and thus, require a
longer integration time for the same output. Large-well devices achieve a good S:N because
they integrate out photon noise. Small-well devices must use mathematical signal averaging to
achieve the same results as large-well devices, but small-well devices can achieve the results in
the
same period of time
. This kind of signal averaging was not possible in the past because
analog-to-digital converters and computers were too slow.
Large-well devices consume large amounts of power, resulting in the need to build thermoelectric
coolers to control temperature and reduce electronic noise. Then, even more power is required for
the temperature stabilization hardware. But small-well devices only need to use signal averaging to
achieve the same results as large-well devices, and have the advantages of remaining cool and
less noisy.
Internal Operation
Pixel Definition
A series of pixels in the beginning of the scan have been covered with an opaque material to
compensate for thermal induced drift of the baseline signal. As the Flame warms up, the baseline
signal will shift slowly downward a few counts depending on the external environment. The
baseline signal is set at the time of manufacture. If the baseline signal is manually adjusted, it
should be left high enough to allow for system drift. The following is a description of all of the
pixels, both as they exist on the hardware device and as they are actually read from the device via
USB:
Pixels on the FLAME-S Pixels on the FLAME-T
Pixel Description Pixel Description
0
–11
Not usable 1
–5
Not usable
12
–29
Optical black pixels 6
–18
Optical black pixels
30
–31
Not usable 19
–21
Transition pixels
32
–2079
Optical active pixels 22
–3669
Optical active pixels
2080
–2085
Not usable 3670
–3681
Not usable