Specifications

in which the fiber is attached from the intensifier directly to
the CCD. The second method is the lens relay which
uses lenses to converge the scene from the intensifier to
the CCD. Both methods have benefits specific to a type
of application. In general, the fiberoptic type has better
light transmission and resolution. The lens coupled type
costs less and holds up better in rugged environments.
A few of the intensifiers have gating capabilities. This fea-
ture allows the tube to be turned on and off at a very rapid
rate (up to 5 nanoseconds). Gating allows for short expo-
sure time to capture events that occur at a very fast rate
such as a pulsed laser beam modulated at a high fre-
quency or an explosion.
Intensifier cameras as a whole have many application
possibilities in low light surveillance, microscopic applica-
tions, and in astronomy.
Lenses
PULNiX America has over 100 different lenses available
to use with the full line of video cameras. The type of lens
that is needed for a particular application depends on vari-
ous factors that we will get into right now.
The function of a lens is to collect reflected light from a
scene and form a focused image of the scene on a cam-
era's sensor plane.
To start off, we must determine the total area the camera
must see. This is called the Field of View (FOV).
The scene that comprises the FOV has horizontal width
(H) and vertical height (V) dimensions. Based on the dis-
tance (L) and the total FOV, we can select a lens to meet
a particular application.
Lenses are described in terms of their focal length (mil-
limeters). The focal length (FL) is defined as the distance
from the center of lens to the CCD array surface. The
focal length will determine the view angle through the lens
which will determine the FOV based on distance to the
scene. Magnification (M) is a number expressing change
in object-to-image size. The human eye has a magnifica-
tion of 1 (M=1). A 1" format camera with a 25mm focal
length lens (≈1") also has M=1. A 2/3" format camera
with a 16mm lens has M=1 and a 1/2" using a 12.5mm
lens gives M=1. This explains why a change in CCD for-
mat size without changing the lens will change the field of
view. This is something that is frequently over looked
when changing camera format sizes in an existing appli-
cation. F/Stop (F/Number , F/#) refers to the speed in
which a lens can pass light. A typical lens would be a
25mm with f/1.4. This translate into a 25 millimeter focal
length with an F-Stop of 1.4. The F/Number can be calcu-
lated by dividing the focal length of the lens by its diame-
ter. As the F/Number gets larger, the light speed
decreases and this usually means a lower contrast level
or image quality. Typically, the faster lenses have larger
diameter optics that will pass more light and usually will
cost more than the slower speed lenses. Lighting condi-
tions should always be considered when selecting lens
speeds.
The following formulas can be used to determine the focal
length which will determine the relative size of the object
viewed.
f= Focal length of the lens (mm)
H= Horizontal dimensions of object (mm)
V= Vertical dimensions of object (mm)
L= Distance from the lens to the object (mm)
For further information concerning lens applications,
please refer to PULNiX Lens Guide.
6
L
V
H
FOV
H = Horizontal Height
H
Side View
Top View
V
V = Vertical Height
Lens
CCD
LFL
θ
= view angle
H
θ
= view angle
V
H&V FOV
Field of View
Format
1"
2/3" 1/2"
H
V
12.8 x L
8.8 x L
6.4 x L
9.6 x L
6.6 x L 4.8 x L
fff
ff
f