Image Processing Reference
Figure1.6 M3 sniperscope, Korean War era.
IR viewer can see the searchlight and shoot at it. These systems were first fielded
on Okinawa during WWII and were very effective.
Near-infrared lights were also used for signaling between Navy ships. The X-12
train light is an example of this technology. It consists of an incandescent lamp
with multiple redundant filaments, surrounded by a cylindrical black glass filter
that passes near-infrared light only. These lights were hung on various parts of
the ship and kept on continuously at night. Friendly ships equipped with near-IR
viewers could see the train lights. These viewers used image converter tubes that
respond to near-IR light. Figure 1.7 shows a C-3 viewer which is equipped with a
long focal length reflective optic. The author is holding one that still works!
Subsequent developments in night-vision technology that have occurred over
the last 50 years have resulted in systems that are much smaller, lighter, and more
sensitive than the early image tubes. These devices can be worn on the head in a
goggle configuration (as shown in Fig. 1.8) or mounted on small arms to enable a
person to see fairly well in extremely low light levels (almost as low as overcast
Figure1.7 The author with a working WWII-era C-3 near-IR imager.