Which settings should I use?
Typical settings are: 100 milliseconds of exposure time per phase frame, 100 mA LED DC for LED power. In ‘Expert mode’ it is possible to change the modulation properties of the camera (Cathode DC and AC level) and of the light source (LED DC and AC level), however for normal use these values do not need to be changed. During the LIFA support or LIFA advanced training session the modulation settings are checked.
It is always good to start with a color map of the camera in absolute scale (by pressing the ‘A’ in the menu bar of the imaging window). Subsequently increase the MCP with 50-100 Volts and check if there is signal on the camera. If signal does not appear please use the ’98’ color scale and play with the phase slider (LIFA Control window). Once there is signal one should move the phase slider to the setting producing the highest intensity (the “maximum phase”), subsequently one can scale back to absolute color scale and increase exposure time. For the best possible lifetime accuracy please make sure that the intensity in the ‘maximal phase’ image reaches a value close to the maximum of the 16 bit range.
Note that when the exposure time is set higher than 330 milliseconds, the intensity will not increase accordingly in live video mode as live mode acquisition is limited to 330 ms. To check the result of the requested integration time, press snapshot (in Expert mode). Please know that once you have pressed snapshot, the camera is still active, thus to turn it off one should press the Idle button.
Typically 12 phase images are taken for acquisition of a phase stack, without averaging. Averaging yields a lower standard deviation. A lower MCP can also yield a somewhat lower standard deviation.