switching on the power supply, and scanning the
forward area until the source of the sound was located
or determined.
Infrared rays, visible only to the
operator, were projected over the sighting area. The
reflected rays, picked up by the electronic telescope,
were converted to a visible image and magnified
according to the power of the telescope. Sighted
objects appeared in varying shades of green,
regardless of their daylight color. Researchers chose
the color green because green light stimulates the
cones without shutting down the rods. This enables
the person using the night scope to look at a relatively
bright picture without losing any night vision.
Night vision capabilities proved to be particularly
effective in combatting enemy infiltration tactics
conducted during periods of darkness. However, a
major problem with the use of infrared instruments
was that the user could be readily spotted by a foe
who also was using infrared instruments or detection
equipment.
To combat this problem, researchers
developed passive devices, devices that only received
light from a source and amplified that light to produce
a picture on a screen. In the following sections, we
will discuss both active and passive devices that are in
use today.
ELECTRO-OPTICAL DEVICES
All electro-optical devices use some source of
power to produce an image of an object through
illumination, amplification, or thermal imaging.
These devices contain electronic components as well
as electro-optical components such as light emitting
diodes, image intensifier tubes, and lasers. Examples
of such devices are night vision goggles and rifle
sights, laser range finders, markers and designators,
and forward looking infrared receivers.
The night vision department of the Naval Surface
Warfare Center, located in Crane, Indiana, is the
central point of contact for all electro-optical
equipment used in the Navy.
BATTERIES FOR NIGHT VISION
EQUIPMENT
Every night vision device uses a battery to
produce image intensification. The battery supplies
voltage that accelerates electrons across an image
intensifier tube. Various types of batteries are used in
Navy and Marine Corps night vision equipment.
Alkaline batteries are inexpensive and readily
available. However, their service life is the shortest of
all the battery types.
Mercury batteries were used as power sources in
earlier night vision equipment but, due to ecological
problems, are now being removed from service.
Nickel-cadmium batteries are used primarily for
training since they require down time while
recharging.
Lithium batteries provide the longest service life
at temperatures above 15 degrees Fahrenheit.
Because of high performance, this type of battery is
used when possible. These batteries must be approved
by the Navy Lithium Safety Review Board before
approval for service use.
Figure 1-1 shows batteries commonly used in
night vision instruments.
Beginning at the upper left and going clockwise;
1. BA-1100/U Mercury Battery (6.5 volts)
2. TD-100A NiCd Battery Pack (14.0 volts)
3. BA-3058/U “AA” Alkaline Battery (1.5 volts)
4. BA-1567/U Mercury Battery (2.7 volts)
5. BA-5567/U Lithium Battery (3.0 volts)
6. BA-1312/U Mercury Battery ( 1.3 volts)
HAND-HELD NIGHT VISION SIGHTS
Hand-held sights are small, lightweight devices
that are used for signaling or map reading.
AN/PAS-6 Metascope
The metascope, illustrated in figure 1-2, is a small
hand-held device used as an aid in detecting infrared
sources. The metascope has an attachable infrared
light source (active) that can be used for signaling.
With the light source attached, the metascope can be
used for map reading.
The metascope weighs 2.5 pound. It has a range
of 1 mile for signaling purposes and 12 inches for map
reading. Its receiver is powered by a 4.3 vdc battery
and its light source is powered by two “AA” alkaline
batteries. The field of view is 26 degrees and the
battery life is estimated at 40 hours at a temperature of
23 degrees Celsius. This unit is being replaced by the
Nite-Eye Pocketscope.
1-2
