Teledyne Princeton Instruments PI-MAX 3, System Manual

Page: 243 / 250

Appendix H Glossary 243
Quantum
Efficiency:
The percentage of incident photons converted to electronic
charge. The throughput of the input windows, the spectral
sensitivity of the photocathode and the CCD array, the
illuminated surface (front or back) of the CCD array, the
intensifier on/off ratio, the MCP resolution, the MCP gain, and the
intensifier-CCD coupling all contribute to the total system QE.
RAM:
Random Access Memory used to store data such as experiment
parameters.
Region of
Interest:
A square or rectangular set of contiguous pixels on the CCD array
that is usually smaller than the full frame. Using an ROI to acquire
data results in a faster readout of the array since data from pixels
outside of that ROI is discarded.
ROI:
Refer to Region of Interest .
Safe Mode:
PI-MAX3 intensifier mode in which the photocathode is
continuously biased off.
Saturation:
Caused when a pixel well is completely filled with charge. Once a
pixel is saturated, additional charge will spillover (bloom) into
adjacent pixels. Ways to deal with saturation include lowering the
array temperature (to reduce the dark charge component),
shortening the exposure time (to reduce the signal component),
and decreasing the gain (also to reduce the signal component).
Scan / Scanning:
The process of reading out the contents of a CCD array.
Super Gen II
Intensifier:
Gen II Intensifier devices that employ novel photocathodes with
extended spectral range or high QE in a particular wavelength.
Vertical Shift
Time:
Reports the speed (in

s) at which a single row will be shifted
vertically.
This information is based on the value in the Vertical Shift box.
The higher the value in that box, the longer the vertical shift time.
This information appears for the Frame Transfer.
Vertical Shift:
Determines the speed of the image transfer from the exposed
area of an array to the masked area. Setting a lower value
increases the shift speed. A higher value gives a slower shift. If the
shift is too fast, not all of the charge will be transferred. If too
slow, image smearing will be increased due to the exposure that
takes place while the transfer is in progress. The default value
gives good results in most measurements.