Optimum performance of the SP2 is obtained when the YAG laser beam is operating in the TEMoo mode. This is defined by a single laser beam spot which has a Gaussian profile. Higher-order modes will have multiple spots, which may not affect the measurement of black carbon incandescence but will almost certainly limit the utility of the scattering data collected. In cases where very high-order modes are present, the incandescence data can also be compromised.

The SP2 beam scan camera and software is designed to facilitate observing and setting the mode of the YAG laser in the SP2. The system consists of a Mightex CCD camera which has been fitted with a high Optical Density (OD) filter. A mounting bracket allows the camera to be mounted in the position normally occupied by the YAG power monitor on the SP2. The light-intensity data from the camera is recorded and processed by a software package made by Visulux, called vBeam. In the Windows 7 32-bit version, the vBeam software has code in it to read only a camera with a specific serial number. If multiple units of the camera and software are purchased, the installed software must be correlated with a given camera. With Windows 7 64-bit version and newer, the drivers should enable the software to find the correct serial number of your camera automatically. In both versions of Windows 7, it is necessary to load the software thru both USB ports so that the camera will be found by the system. If the software is loaded into one port and the camera is plugged into the other USB port, the camera will not be found.