CHAPTER 1 - SYSTEM OPERATIONLSM 880 Left Tool Area and Hardware Control Tools ZEISS10/2014 V_01 000000-2071-464 1215.2.9.3 Using GaAsP Detectors and thetemperature controlled side PMT forPhoton Counting ImagingIn the LSM Imaging Setup tool activate any GaAsPdetector like BiG.2, the 32 channel GaAsP Arraydetector or the temperature controlled side PMT(Ch2).Select Photon Counting for the detector in theChannels Tool (Fig. 159).In photon counting imaging a Digital Offset andDigital Gain slider is available, which can be used toadjust brightness and contrast of the image duringscanning.In photon counting mode an artificial maximum ofdetectable photons is set. For all GaAsP detectors andthe side PMT (CH2) this value is defined byCRmax/digital gain (CR max = maximal count rate definedby the software, which is 4 MHz for the BiG.2 andCh2 and 2 MHz for CHs (32 channel GaAsP Array).Higher count rates are regarded as saturation. Notethat too much light on the detectors (higher countrates for some ms) leads to detector shut down toavoid damage.(1) Display of Photon Count ImagesThere are two ways photon counting images canbe displayed in the LSM software, in analog (greyvalue) or counting (raw data) mode.You can toggle between the two modes in theMaintain area Options / System Options in theHardware tab by deactivating or activating theKeep raw data for photon count detectorscheck box (Fig. 160).If the box is checked, you will obtain the photoncounts, if unchecked, grey values corresponding tophoton counts.Fig. 159 Channels tool – Photon countingmode for GaAsP detectorFig. 160 Hardware tab in the SystemsOptions tool/Maintain tab
