Princeton Instruments ProEM+ EMCCD, User Manual

Page: 68 / 152

Chapter 5 Operation 67
67

Clean Before Exposure { Clean Before Exposure } is only provided for cameras
that have a Frame Transfer CCD and is only available for selection when in Full
Frame mode is active. Normally, cleaning occurs until the acquisition starts.
When
Clean Before Exposure is active, cleaning occurs up until acquisition
starts and the entire CCD will be cleaned once right after the readout occurs. It is
a clean operation for the next exposure and it matters only when multiple images
are taken with a short exposure time.
Note:
Clean Before Exposure is NOT relevant when you are in a triggered
mode.

Continuous Cleans { Clean Until Trigger } is available when the start of exposure
is tied to an external trigger. In WinX, this cleaning becomes active when
External Sync timing mode is selected. In LightField, it becomes active when
Trigger Response is set to Readout Per Trigger or Shift Per Trigger . Refer to
Figure 44 (page 81) to see a timing diagram that shows the LightField Clean
Until Trigger .

Skip Serial Register Clean (deselected) { Clean Serial Register } The Top margin
inactive parallel strips on a CCD are made up of the dark pixels that come before the
active strips on a sensor as they exit to the serial register. When these are available
(i.e., Pre Dummies {Top Margin} > 0), they serve the purpose of cleaning the serial
register before readout of the active strips. In LightField, if there are no inactive
parallel strips (i.e., {Top Margin} = 0), selecting
Clean Serial Register forces a
clean of the serial register before readout of the active strips.
Readout
Introduction
The ProEM+:512B/512BK and 1024B models use frame transfer CCDs with 512x512
and 1024x1024 active pixels, respectively; these frame transfer CCDs also have an
equivalent number of “frame transfer or masked” pixels as shown in Figure 33. The
ProEM+:1600
(2)
and 1600
(4)
models use full frame CCDs with 1600x200 and
1600x400 active pixels, respectively.
Note:
Typically there are additional rows and columns for internal reference.
In standard frame transfer mode, the sensor area is exposed for certain time; and the
acquired image data are then transferred to frame transfer area before reading the data out
via the multiplication gain register or standard serial register. In standard full frame
transfer mode, the sensor area is exposed for certain time; and the acquired image data
are then read out via the selected register. Region of Interest (ROI) and/or binning can be
used to improve the time resolution, limited to a millisecond regime. For more
information on the CCD exposure-readout operations, see
“Exposure - Readout Modes”
(page 71).