Image Acquisition; Description Of How The Ccd Functions - Hamamatsu Photonics C8484-16C Instruction Manual

C8484-16C Instruction manual Ver.1.5

9. IMAGE ACQUISITION

9-1

DESCRIPTION OF HOW THE CCD FUNCTIONS

The all-pixel-readout interline transfer CCD used in this camera is arranged as shown in
Figure 9-1. Incident light at the CCD is converted by photosensors to electrical charges
which are transmitted through a shielded vertical transfer CCD (VCCD) and a horizontal
transfer CCD (HCCD) to a final output charge-voltage conversion amp. The sensor gate is
opened by the readout signal, and the charges generated by all of the photosensors are
transmitted unmixed to the VCCD, completing the exposure.
In addition, an electronic shutter signal is applied to the CCD, allowing any accumulated
charge in the photosensors to be discharged.
 Binning: Accumulated charges for a specified number of pixels in the vertical and
horizontal directions on the CCD are calculated and combined (binned), then
read out from the CCD. With this camera, binning can be set to 22, where two
pixels in the vertical and horizontal directions are combined, 44, where four
vertical and horizontal pixels are combined.
 Exposure time:
When set to the normal CCD scanning mode, this is as shown in Figure 9-2.
Exposure time is the elapsed time between one readout signal and the next;
this interval is at least as long as the time necessary for all of the charges from
the CCD to be read out.
CCD exposure
Readout signal
from CCD chip
Digital data
output
12
Photo-diode
Vertical CCD
ON-chip AMP
Figure 9-1
Exposure time
Readout period
Figure 9-2
Sensor gate
Horizontal CCD