User manual

Alternate Normal mode

In "Alt-Normal", it is possible to achieve higher QE in the NIR (peak QE of

approximately 65%) by manipulating the CCD clock voltages. Also, in this

high-sensitivity mode, the preamplifier is switched off during the exposure to

eliminate the background generated by preamplifier glow. In this clocking

mode, irrespective of what the exposure time is, the camera operates in

"nonoverlapped" or "sequential" mode.

alternate-normal - high sensitivity

normal - high frame rate

Wavelength (nm)

200 300 400 500 600 700 800 900 1000 1100

QE (%)

Figure 3. QE for Normal and Alternate Normal Modes

Antiblooming Typically, interline CCD devices are designed with antiblooming capabilities.

To prevent excess electronic charge from migrating to adjacent pixels, "drains"

are built into the CCD. These drains remove any excessive charge generated

from an overexposed pixel. Sony interline CCDs will prevent blooming for

optical signals greater than 1000 times the full-well capacity of a single pixel.

However, the extended QE capabilities of the Sony ICX285 in the

CoolSNAP

reduce the antiblooming suppression for certain modes. In

normal mode, the CCD operates with typical antiblooming suppression. But

in alternate normal mode, the enhanced sensitivity causes a reduction in

antiblooming to greater than 100 times single-pixel full-well capacity.

Triggered

Operation

CoolSNAP

and CoolSNAP

offer several methods of integration with

external trigger sources, such as delay generators or laser pre-triggers. Each

camera has a 26-pin, high-density I/O connector (pinout functions are

described on page 20) on the back for trigger-in/out and various TTL input

and output operations. A special cable is available to access primary signals

such as "Trigger-in," "Trigger-invert," "Expose out," "End of frame," and

"Interline shift." In the default mode, the camera triggers on the rising edge of

a TTL signal. To invert the triggering polarity, the "Trigger-invert" must be

grounded, which can be done with a 50-ohm terminator. The CoolSNAP

cameras support the trigger modes described on the following page (Note that

all of these modes are operated in "nonoverlapped" mode).

10 CoolSNAP

/CoolSNAP

User Manual