Falcon2 4M, 8M, and 12M Camera User's Manual
67
Teledyne DALSA
03-032-20107-03
If the cam era is ru n at exp osu re tim e that is significantly higher than the calibration exp osu re, an
ad d itional Pixel Rep lacem ent Calibration m ay be requ ire
The gain (PRN U) calibration is p erform ed next to d eterm ine the m u ltip lication factors requ ired to bring
each p ixel to the requ ired valu e (target) for flat, w hite ou tp u t. For the m onochrom e cam eras, the target is
d eterm ined by the u ser (See
flatfieldCalibrationTarget).
The color cam era requ ires a sep arate target for each
color w hich is calcu lated as 23 % higher than the average p ixel for the given color.
It is im p ortant to d o the FPN correction first. Resu lts of the FPN correction are u sed in the PRN U
p roced u re.
Let’s go through a flat field calibration example:
1.
The cam era is p laced in
internal exposure and frame rate
. Make su re that the area of interest
(AOI) is set to the fu ll w ind ow (i.e. Wid th=SensorWid th and H eight=SensorH eight)
.
N o other
exp osu re m od e or AOI configu ration w ill allow FFC calibration. See
ExposureM ode
,
TriggerM ode
,
OffsetX
,
OffsetY
,
W idth
,
Height
.
2.
Settings su ch as fram e rate, exp osu re tim e, etc. are set as close as p ossible to the actu al op erating
cond itions. Set
system gain to 1
and
background subtract to 0
, as these are the d efau lts d u ring
FFC calibration. See
GainSelector, Gain, BlackLevelSelector,
and
BlackLevel
.
3.
Select
correction active set to user flat field 1
. Go to
flat field correction mode,
select
calibration
. See
flatfieldCorrectionCurrentA ctiveSet
, and
flatfieldCorrectionM ode.
4.
Clear existing coefficients. See
flatfieldCalibrationClearCoefficient.
5.
Place the cam era in the d ark (i.e. cover lens) and ru n
FPN calibration
. This p erform s the FPN
correction and saves the FPN coefficients to tem p orary m em ory. See
flatfieldCalibrationFPN .
6.
Calibration m od e enables both FPN and PRN U correction. Verify signal ou tp u t is close to 0 DN .
7.
Illu m inate the sensor to 65 % satu ration , u sing a high qu ality w hite refer ence.
8.
Set
flat field target
to 80 % satu ration (m onochrom e only). See
flatfieldCalibrationTarget.
9.
Select Gain Calibration Mod e as either H igh Gain or H igh Resolu tion
10.
Ru n
Gain (PRN U) calibration
. See
flatfieldCalibrationPRN U.
11.
[Op tional] Set the
exposure time
to {X % longer than } the longest valu e that w ill be requ ired by
the user‘s system. Set the
pixel replacement calibration threshold
to 60. Ru n
pixel replacement
calibration.
See
Hot Pixels and Long Exposure Times
for m ore inform ation abou t w hy this is
necessary. See
ExposureTime,
flatfieldCalibrationPixelReplacementThreshold and,
flatfieldCalibrationPixelReplacement
12.
Save
the flat field calibration :
flatfieldCalibrationSave.
Here is the factory calibration procedure for the 8M camera:
1.
The cam era is p laced in fu ll internal, 8 tap s, 10 bits, active w ind ow (3328 x 2816, only available to
factory), system gain 1, color gain 1, backgrou nd su btract 0, global FPN calibrated su ch that d ark
FPN is 30 DN (10 bit) 50 fp s, 1500 µs exp osu re. For color, u se 20 fp s, 25000 µs exp osu re. This last
p art is im p ortant (m ono: 50 fp s, 1500 µs exp osu re. Color: 20fp s 25000 µs exp osu re) and ensu res
that the cam era is in non -concu rrent m od e. In non -concu rrent m od e, read ou t and integration d o
not overlap thu s elim inating som e resid u al artefacts.
2.
The cam era is p laced in the d ark and
FPN
Calibration is ru n.
3.
With FPN correction on the sensor is illu m inated (Light Sou rce: Broad band Qu artz H alogen, 3250
K, w ith a 750 nm cu t-off filter) w ith a light level of 26.4 µW/ cm
2
(10 BPP). This ensu res each
