In focus mechanism, there is a prismatic
decomposition system splitting the incidence
light into four color-beams and one
panchromatic beam. The CCD array for every
band mounted at the focus plane after prism.
Fig 3 is conceptual diagram of splitter prism
butted prism and CCD structure. Four multi-spectral
array lines at the same direction to
the ground scene, while panchromatic beam
is in another field symmetric to optical axis.
Apart from red, green and near infrared bands,
especially it places a blue band (0.4µm –
0.52µm) which is sensitive to coloring
material of plant of chlorophyll and
phylloerythrin, suitable for measurement of
water permeation. It is better for use in
drowning map of coastal seawater area and
distinguishing soil and vegetation cover
especially deciduous plant and acicular plant
The CCD device transfers the received light
energy into photoelectron. Then the
photoelectric signals are been processing in
sampling, amplifying, filtering, composition
of even and odd, and encoding by CCD
imaging circuit. Finally via data transmission
device the processed signals is been
transferring to the ground stations.
Figuer 3. The Conceptual Diagram of CCD Splitter
Relative calibration device consists of lamp
and illuminating optical system. It uses the
multistage-stable light- source regularly
illuminating optical system and CCD array,
checks the changes of radiant character of the
camera, the result are provided for radiant
correction of image.
Conclusion
The CCD camera is a product of high
technology, so it is more difficult in research
and development. In order to do the task
better, special works to resolve the key
technologies are done and also doing
optimization in system designation. Every
kind of necessary tests concluding flight
dynamic environment test, thermal vacuum
test, and focusing test in vacuum condition,
have been done in developing period. The
results of tests demonstrated that the
performances of the CCD camera fulfill the
mission requirements, and the reliability is
good. After research and development in
many years, the CCD camera is expected to
flight in orbit with CBERS after the satellite
shall have been launching at late of 1999.
Then doing test in orbit and providing daily
routine application. It will be the first
generation of long-life CCD camera in space
for China.
