NIGHT VISION CARS
what is this system
It
is a known fact that after dark it is impossible for man to see beyond a few
metres in length without the correct illumination and this illumination also
has its constraints and during the night times the reflectivity also increases
and it is more a judgemental driving rather than a calculative one. The night
vision helps the drivers in such cases. It makes a negative image of the image
captured by the camera and illuminates the darker part thus enabling the driver
to see what lies ahead by looking at the monitor that has been attached in
front of the diver on the dash board or some other convenient part of the
steering.
how its working
Night
vision devices (NVD) work in the near-infrared
band at a wavelength
of about 1 Micrometer.
For comparison, human visual range is about 0.4 to 0.7 micrometers. Unlike thermal imaging systems,
which may operate on complete darkness
using heat radiation signatures, well beyond the visible light spectrum, NVD's
rely on ambient
light, often from the moon
and stars. The intensifier tubes use the photoelectric effect.
As a photon collides with a detector
plate, the metal ejects several electrons
that are then amplified into a cascade of electrons that light up a phosphor
screen. Often a dim star in the sky is enough to illuminate an entire field.
The
night vision image does not have color information, and hence monochromatic displays
are sufficient. A green
phosphor (P22) display is generally used as the human eye
is most sensitive to the color green in this wave length, which falls in the
middle of the visible light spectrum.
The
latest generation of NVD use a green yellow Phosphor (P43), and gives the
operator a much more comfortable viewing experience. Current development by
Photonis, have also created a gray scale or black & white Phosphor (P45).
``````THANKS FOR YOUR VISIT WE NEED YOUR SUPPORT``````````
No comments:
Post a Comment