Time-Series Analysis (Phasor)

Notice that the phasor value are way off the universal circle, due to the absence of calibration.

To use this set of points as a phasor calibration curve, make sure the Calibration Lifetime value corresponds to the known value for the ROI which was analyzed, and right-click in the Phasor Graph and choose Phasor Calibration >> Time Series Calibration >> Use as Phasor Calibration Curve:

This stores the series of uncorrected phasor values as references, which will be later used to correct other phasors calculated for different ROIs of unknown lifetime characteristics.

Once a calibration curve has been defined, the corresponding Task Completion Indicator LED lights up.

To clear this definition, use the Phasor Calibration >> Time Series Calibration >> Clear Calibration Curve item of the Phasor Graph context menu.

Notice that the Time Series Calibration sub-menu provides the option to save (Save Phasor Calibration Curve) or load (Load Phasor Calibration Curve) a calibration curve once it has been defined. The XML file extension is automatically set to .calN to distinguish it from a single time point calibration file (.cal extension).

Applying this calibration curve (by checking the Use Phasor Calibration Curve checkbox) will collapse all data points to a single one on the Universal Circle, as expected.

2. Time Series Analysis

Once this is done (and two reference phasors have been defined - see below):

• Check the Use Calibration Phasor checkbox

• Select another ROI of interest

• Perform a new time-series analysis (Ctrl+T) 

The result (after some computation) should be phasors values within the universal circles and a phasor ratio curve (Phasor Ratio Analysis panel) hopefully exhibiting some meaningful behavior, such as the one shown below:

with the corresponding lifetime curve (Lifetime Analysis panel):

Note that it is possible to interrupt this calculation by pressing the Abort button appearing on the right of the Data File Folder Path control.

Modifiying the reference phasors after a time-series analysis

In some cases, it is not possible to define the reference phasors without prior knowledge. In the particular case illustrated below, the phasor "trajectory" strongly indicates that the sample is comprised of a mixture of two single lifetimes, one of which (the lowest one) becomes increasingly present as time goes.

In this case, it is natural to use the Phasor Ratio References >> Use UC/Cursor-Defined Line Intersections tool (or the Use UC/Fitted Line Intersections tool)  to define two phasor references with the Line tool described in the Phasor Graph page of the manual, and then use these two new references to compute phasor ratios.

This latter step is performed with the Phasor Ratio Calculation >> Compute Time-Series Phasor Ratio shortcut menu of the Phasor Graph.

A new phasor ratio time series plot is computed and displayed in the Phasor Ratio Graph (Phasor Ratio Analysis panel) and the corresponding lifetime values are plotted in the Lifetime Graph (Lifetime Analysis panel). There is no need to recompute the whole phasor time series.

"Retracing" the Phasor Trajectory

It can be useful to "retrace" a phasor trajectory by moving through the different time points post analysis. This is done by checking the Single Step checkbox below the Phasor Graph (Phasor Graph panel) and moving the Phasor Frame Slider next to it:

A single phasor corresponding to the frame whose number is indicated to the right, is displayed in the Phasor Graph. It is possible to use or not use a Phasor Calibration or Phasor Calibration Curve.

Note that the Image Source is not affected by these manipulations.

If the checkbox is checked during a time-series analysis, a single phasor (the current one) will be displayed in the Phasor Graph. Unchecking the Single Step checkbox will show the full phasor series.