Operation And Features; Functional Description - Basler L800k User Manual

3 Operation and Features

3.1 Functional Description

BASLER L800
electronic exposure time control and area of interest scanning. Exposure time can be controlled
via an external trigger (ExSync) signal. The ExSync signal facilitates periodic or non-periodic pixel
readout.
When exposure is controlled by an ExSync signal, the camera can operate in either an edge-
controlled, a level-controlled or a programmable mode. In edge-controlled mode, charge is
accumulated over the entire period of the ExSync signal and a rising edge of ExSync triggers the
readout of accumulated charges from the sensor elements to the CCD shift registers. In level-
controlled mode, charge is accumulated when the ExSync signal is low and a rising edge of
ExSync triggers the readout. In programmable mode, exposure time can be programmed to a
predetermined time period. In this case, exposure begins on the rising edge of ExSync and
accumulated charges are read out when the programmed exposure time ends.
A free-run mode that allows the camera to operate without an ExSync signal is also available. In
free-run mode, the camera generates its own internal control signal and the internal signal is used
to control exposure and charge readout. When operating in free-run, the camera outputs lines
continuously.
At readout, accumulated charges are transported from the light-sensitive sensor elements (pixels)
to the CCD shift registers. The charges from the odd pixels in the left half of the sensor, the
charges from the even pixels in the left half of the sensor, the charges from the odd pixels in the
right half of the sensor and the charges from the even pixels in the right half of the sensor are
handled by separate shift registers as shown in Figure 3-1. As charges move out of the shift
registers, they are converted to voltages proportional to the size of each charge. Shifting is
clocked according to the camera's internal data rate.
The voltages moving out of each shift register are digitized by a 14 bit analog-to-digital converter
(ADC). Gain and offset functions are performed on the pixel data using digital means. For single
and dual video data output mode the digitized pixel data is reordered in the camera's FPGA so
that the pixels will be transmitted from the camera in sequential order from pixel 1 through pixel
8160. For dual separated video data output mode the pixel data is directly transmitted from the
camera without reordering.
Pixel data is transmitted from the camera to the frame grabber using a format compatible with the
Camera Link standard (see Section
stream or a single pixel stream. Pixel data can be transmitted at ten bit or an eight bit depth.
BASLER L800
k
line scan cameras employ a CCD-sensor chip which provides features such as
k
2.3
Draft
for details). L800 cameras transmit data as a dual pixel
k
Operation and Features
3-1