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How VisualSpreadsheet Determines Parts / Million and Particles / mL
There are several pre-defined parameters (i.e. Particle Properties) that are measured by
VisualSpreadsheet
that are required for the calculation of Particle Concentration (P/mL or PPM).
·
Particle Count
·
Area Based Diameter (ABD)
·
Equivalent Spherical Diameter (ESD)
·
Total number of camera images taken for the full duration of the analysis
There are also several parameters that are user-defined that VisualSpreadsheet uses in the calculations.
·
Acceptable range of camera view
·
Flow cell depth (D) in µm
The acceptable range of camera view is dependent on the properties of the digital camera. Depending
on the model of the digital camera, the maximum and minimum number of pixels may be different than
the values used below in the example calculations. Typical values for camera pixels are 1024 x 768 and
1280 x 960. The FlowCAM has factory default settings that include the correct values for the installed
digital camera. VisualSpreadsheet determines the acceptable region within the camera’s field of view
via the following process. Note that the acceptable range of the camera can be changed or “constrained”
by the user:
Left
= user-specified number (default value = 0 pixels)
Right
= user-specified number (default value = 1279 pixels)
Top
= user-specified number (default value = 0 pixels)
Bottom
= user-specified number (default value = 959 pixels)
With these numbers specified, VisualSpreadsheet
determines the height and width of the acceptable
region with the following calculations:
Height (H) = (1 + (Bottom - Top)) x the Calibration Factor (µm per pixel)
Width (W) = (1 + (Right - Left)) x the Calibration Factor (µm per pixel)
Depth (D) = User defined value determined by the dimensions of the flow cell used during the analysis
Note: The Calibration Factor (used to calculate H and W) is factory determined and set as a default
value used by VisualSpreadsheet.
The Volume per Picture is calculated as D × H × W (µm
3
)
