Galvo Controller Board Configuration

Standard Cambridge Technologies 671 series galvo controller accept two input signals:

• Galvo Position
• Galvo Position Offset

ScanImage controls the stimulation pattern using the Galvo Position signal. To correct for sample motion, ScanImage uses the Galvo Position Offset Signal, which is updated independently of the Galvo Position signal.

R124 and R93 determine the gain of the inverting amplifier shown in the figure on the right. Since NI DAQ boards can drive analog outputs +-10V, no additional amplification is required. Using the formula Vout = -Vin * R93/R124 it can be seen, that  R93 and R124 should be selected to have the same value (20kOhm should be sufficient for most applications).

To determine R85, review page 13 of the Series 671 instruction manual:

Wiring

To use motion correction the following signals need to be connected:

• XY Galvo Position (see Configuring LinScan)
• XY Galvo Position Offset
• XY Galvo Position Feedback

The XY Galvo Position Feedback is used to calibrate the position offset signal relative to the galvo position signal.

The galvo position and offset inputs are located on connector J1 of the Cambridge Technologies galvo controller board. Assuming these inputs are configured to be non-inverting single ended (W4 1-3 and 4-6 jumpered), the following wiring scheme can be used:

%% LinScan
deviceNameAcq   = 'PXI1Slot3';      % string identifying NI DAQ board for PMT channels input
deviceNameGalvo = 'PXI1Slot3';      % string identifying NI DAQ board for controlling X/Y galvo. leave empty if same as deviceNameAcq
deviceNameAux   = 'PXI1Slot3';      % string identifying NI DAQ board for outputting clocks. leave empty if unused. Must be a X-series board

%Scanner position feedback
XMirrorPosChannelID = 5;            % The numeric ID of the Analog Input channel to be used to read the X Galvo position (optional).
YMirrorPosChannelID = 6;            % The numeric ID of the Analog Input channel to be used to read the y Galvo position (optional).

%Scanner control
XMirrorChannelID = 0;               % The numeric ID of the Analog Output channel to be used to control the X Galvo.
YMirrorChannelID = 1;               % The numeric ID of the Analog Output channel to be used to control the y Galvo.

% (optional) Mirror position offset outputs for motion correction
deviceNameOffset = 'Dev1';          % string identifying NI DAQ board that hosts the offset analog outputs
XMirrorOffsetChannelID = 0;         % numeric ID of the Analog Output channel to be used to control the X Galvo offset.
YMirrorOffsetChannelID = 1;         % numeric ID of the Analog Output channel to be used to control the y Galvo offset.
XMirrorOffsetMaxVoltage = 1;        % maximum allowed voltage output for the channel specified in XMirrorOffsetChannelID
YMirrorOffsetMaxVoltage = 1;        % maximum allowed voltage output for the channel specified in YMirrorOffsetChannelID

%% Photostim
photostimScannerName = 'LinScan';   % Name of scanner (from first MDF section) to use for photostimulation. Must be a linear scanner
%Monitoring DAQ AI channels
BeamAiId      = 7;                  % AI channel to be used for monitoring the Pockels cell output

Operation

To enable sample tracking, perform the following steps:

• Start the Photostimulation module by selecting 'Start' in the Photostimulation Controls window
• Start a Focus/Grab/Loop
• Right click the live image in one of the channel display windows and select 'Set motion correction reference'
• Right click the live image in one of the channel display windows and select 'Enable motion correction'
• (Optional) Right click the live image in one of the channel display windows and select 'Show motion'
• (Optional) Enable the 'Monitor Show' option in the Photostimulation Controls window

The Photostimulation module is now tracking the sample by updating the offset signal whenever motion is detected.