Blanking settings

What are the blanking settings?

Zapit blanks the beam when moving between points. The defaults in the settings file work with 5 mm ScannerMax galvos. For other galvos you may need to tweak them. You should verify these settings before starting experiments. The settings we are interested in are:

• experiment.blankingTime_ms defines the number of ms during which the beam is switched off and the scanners move from one point to the next.

• experiment.blankOnsetShift_ms and experiment.blankOffsetShift_ms are used to control the relative start and end time of the laser blanking with respect to the motion time period of the beam. These settings take into account the lag between the scanner command signal and the scanner motion.

Setting up the system for testing

Start Zapit and run the following to do a fake calibration:

hZP.applyUnityStereotaxicCalib
hZP.scannersCalibrated=true;

Connect:

1. AO0 to channel 1 of your osciloscope and also to the X scanner control input using a T.

2. Connect the X scanner feedback signal to channel 2 of your oscilloscope.

3. Connect AO2 to channel 3 of your osciloscope.

Load the stimulus config file called uniAndBilateral_5_conditions.yml You will find that in the examples folder. In the second tab in the GUI, select condition 2 and present it. You should see waveforms appearing on the scope. A system that is well set up should look as follows:

Waveforms used to check blanking parameters. Yellow: X scanner control signal. Blue: X scanner feedback signal. Magenta: laser analog control signal. Note laser is off (low) during the time the mirror is moving.

Should your traces indicate that the blanking time is not correctly synchronised to the motion time, you can alter the relative start and stop of the laser blanking by altering experiment.blankOnsetShift_ms and experiment.blankOffsetShift_ms To do this, simply stop the stimulation in the GUI and do, say, hZP.settings.experiment.blankOnsetShift_ms=-0.2 Then try the stimulation again. The settings are automatically saved to the YML file. i.e. If you start and stop Zapit, the new blanking setting will persist.