CONFOCOR
3
ConfoCor 3
Photon Counting Imaging with the ConfoCor 3
Carl Zeiss
02/2010 M60-1-0025
e
135
The Pinhole (PH4) can be adjusted in x and y in the
Maintain
register of the Left tool bar area
(Fig.
152). Open the
Adjust Pinhole and
Collimator
tool and select
PH4
in the Name
display box (Fig. 153). Use the same procedure as
for normal PMTs. Either trigger an automatic
pinhole adjustment or adjust manually by inspec-
ting the intensity from an image. The pinhole
should be set at maximum intensity.
If
Store Pos
is pressed, the current settings
will be taken for every image application
using channel 4 and the attached
ConfoCor
3 module. No realignment is
necessary if toggling between Imaging and
FCS measurements that might use slightly
different Pinhole 4 positions.
In photon counting imaging you do not have
electronic gain and offsets, neither is electronic
amplifier gain available. Instead a
Digital Offset
and
Digital Gain
sliders are available, which can
be used to adjust brightness and contrast of the
image during scanning.
In photon counting mode an artificial maximum of
detectable photons is set. For APD this value is
defined by CR
max
/digital gain (CR
max
= maximal
countrate defined by the software, which is 4 MHz
for the APD). Note that at a prolonged time over 4
MHz APD detectors will shut off to avoid damage.
For example, at gain 1 the maximum count rate is
4 MHz (corresponding to a maximum of 4
detectable photons/µs) for APDs. These settings
define the dynamic range of the images.
9.14.2
Display of Photon Count Images
There are two ways photon counting images can
be displayed in the LSM software, in analog (grey
value) or counting (raw data) mode.
You can toggle between the two modes in the
Maintain
area
Options / LSM Options
in the
Hardware
register by deactivating or activating
the
Keep raw data for photon count detector
check box (Fig. 154).
If the box is checked, you will obtain the photon
counts, if unchecked, grey values corresponding to
photon counts.
Fig. 152
Left tool area with Maintain
selected
Fig. 153
Adjust Pinhole and Collimator tool
Fig. 154
Hardware register in the LSM
Otions menu
