GLYCO DOC GEL IMAGING SYSTEM - Bio-Rad

Theory of Operation
3.0 THEORY OF OPERATIONS
During exposure, the Imager’s CCD (Charge Coupled Device) detector collects photons emitted by the fluorophore
in a prepared gel. The detector is a semiconductor grid of approximately 180,000 cells for collecting
these photons. Each cell in the grid can collect up to 65,535 charge units per exposure. If a cell receives
more than 65,535 charge units, the excess charge units spill into the surrounding grid squares (in a phenomena
called “blooming”), and that area of the gel is considered saturated. These values serve as the raw
data for band analysis.
Because computer monitors typically display a maximum of 256 shades of gray, the computer must scale
each grid cell’s value to a value between 0 and 256, where 0 is absolute white, and 256 is absolute black.
Each “pixel” (picture element) on the monitor is illuminated at a corresponding level of brightness. This
value is a pixel’s grayscale value.
UV SOURCE
(350nm to 400 nm)
EXCITATION FILTER
(NOT USER-SELECTABLE)
GEL
EMISSION FILTER
(FILTER TYPE IS SELECTED
USING THE SWITCH ON THE
BACK OF THE IMAGER)
CCD CAMERA/
DETECTOR
Figure 9. Imaging System Functional Diagram
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