C13440-20CU / C13440-20CU01 Instruction manual_Ver.1.3
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5. FEATURES
(1) Readout noise
In the camera, the pixel amplifier is optimized: it has high gain from optimizing the semiconductor
process, and the difference among pixel amplifiers are greatly minimized. In addition, there is
on-chip CDS (correlated double sampling) circuit, which plays an important role in achieving low
noise. Moreover, the sensor features a split readout scheme in which the top and bottom halves
of the sensor are readout independently, and the data of each horizontal line is read by 2 lines of
column amplifier and A/D in the top and the bottom in parallel and simultaneously. As a result, it
achieves very fast readout speed while keeping very good low-noise performance.
The camera has lower readout noise (1.0 electrons (median), 1.6 electrons (r.m.s)) than the
conventional cooled CCD camera. Moreover, high-speed readout (100 fps with 2048 pixels ×
2048 pixels) with very low readout noise, which was impossible, can now be achieved.
In addition, the camera can achieve further lower readout noise (0.8 electrons (median), 1.4
electrons (r.m.s) with slow scan mode (30 fps with 2048 pixels × 2048 pixels).
(2) Cooling structure
In the camera, the CMOS image sensor is cooled down by a peltier element to suppress the dark
current. If the CMOS image sensor is exposed to the atmosphere, condensation of the moisture
from the air might occur. However the camera has a special hermetic chamber structure to isolate
the sensor from the atmosphere, and the chamber is filled with nitrogen gas.
(3) Pixel number and pixel size
CMOS image sensor has 6.5 µm x 6.5 µm pixel sizes that is equivalent to conventional CCD
image sensor (2/3 inch, 1.3 megapixels). Also, the camera can observe a wider field of view
because the pixel number is about 3 times that of the conventional CCD image sensor (2/3 inch,
1.3 megapixels)
(4) Readout methods
The camera has a variety of readout modes. In addition to full resolution readout mode (1×1),
sub-array readout and binning readout (2×2, 4×4) are supported.
(5) Frame rate
CMOS image sensor which this camera adopts realizes both low noise (1.0 electrons (median)
1.6 electrons (r.m.s)) and high speed readout (100 fps with 2048 pixels x 2048 pixels)
simultaneously, by a split readout scheme in which the top and the bottom halves of the sensor
are readout independently, and the data of each horizontal line is read by 2 lines of column
amplifier and A/D in the top and the bottom in parallel and simultaneously.
(6) Real-time correction functions
There are a few pixels in CMOS image sensor that have brighter or darker intensity, and a few
pixels that have slightly higher readout noise performance, when compared to surrounding pixels.
The camera has a real-time variant (defective) pixel correction feature to further improve image
quality. The correction can be performed in real-time without sacrificing any of the readout speed.
(7) Data reduction functions
The camera provides a maximum 4.0 megapixel resolution at a rate of 100 fps and with 16 bit
intensity levels per pixel. With these conditions, the camera outputs 800 MB of data per second,
making it necessary to store a large amount of data. With data reduction functions now
available in the camera, it is possible to select reduced areas of the image and/or reduced
intensity levels to transfer and store only the data of interest.
