Falcon 4M Camera Manual
Teledyne DALSA
03-032-20044-03
47
4)
Correction resu lts are valid only for the cu rrent analog offset valu es. If you change
this valu e, it is recom m end ed that you recalcu late you r coefficients.
Let‘s go through a flat field calibration example:
1)
The cam era is p laced in
sem 2
(no other exp osu re m od e w ill allow FFC calibration )
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 d igital gain to X1 (
ssg 0 4096
) and backgrou nd su btract
to 0 (
ssb 0 0
) as these are the d efau lts d u ring FFC calibration.
3)
Place the cam era in the d ark and send CCF, this p erform s the FPN correction and
au tom atically save the FPN coefficients to non -volatile m em ory
4)
Set
epc 1 0
, w hich enables the FPN correction and verify the signal ou tp u t is close
to 0 DN . Leave
epc 1 0
for the next step since the
cpa
target assu m es there is no
FPN . This is im p ortant on the 4M60/ 30 d u e to the large d ark offset valu es.
5)
Illu m inate the sensor, su ch that w ith EPC 1 0, it reaches 50 - 70 % satu ration.
6)
Send
cpa 2 T
w here T is typ ically 1.3X the average ou tp u t level. This is im p ortant
since if the target is too low (<1.1X), then som e p ixels m ay not be able to reach fu ll
sw ing (1023 DN ) d u e to correction s ap p lied by the cam era.
H ere is the factory calibration p roced u re for Snap shot Mod e 1 (
efd 1
):
1)
The cam era is p laced in
sem 2
,
sot 320
,
clm 16
,
efd 1
,
snd 1
, fu ll w ind ow ,
ssg
0 4096
,
ssb 0 0
,
sao 0 0
,
ssf 55
,
set 2000
. This last p art is im p ortant,
ssf
55
and
set 2000
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 artifacts associated w ith concu rrent m od e.
2)
The cam era is p laced in the d ark and
ccf
is ru n
3)
With
epc 1 0
the sensor is illu m inated (Light Sou rce: Broad band Qu artz H alogen,
3250 K, w ith a 750 nm cu toff filter) w ith a light level of 22.8 W/ cm
2
. This ensu res each
cam era w ill have the sam e resp onsivity since the light level and target valu e are
alw ays the sam e. Typ ical ou tp u t levels for the cam era at this light level are 650.
4)
The sensor w ind ow at this p oint has been cleaned thorou ghly su ch that there are no
significant blem ishes p resent.
5)
Send
cpa 2 840
. Typ ically this yield s an average PRN U coefficient of abou t 1.3X.