Note: Descriptions are shown in the official language in which they were submitted.
20424~9
COMPACT MULTIPLE-FUNCTION PERISCOPE
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the invention is ~hat of periscopic
vision provided by periscope or episcope.
More precisely, the invention relates to a
multiple-function periscope that can be used, notably,
to obtain daytime vision with standard optic means, and
night-time vision, by means of a standard light
intensifier for example.
The invention can be applied especially in
observation instruments for armored vehicles and,
notably, for tanks. More generally, the periscope of
the invention may be used in all cases where the
observer has to be isolated from the observed field and
where it is necessary to have~ firstly, means of direct
vision by optic channels and, secondly, electronic
display means including, for example, a light
intensifier, an infrared detector or a camera, with CCD
or other type of sensor.
2. Description of the Related Art
In the particular case of armored vehicles, for
daytime vision, the driver has a standard optic
periscope known as a daytime channel, comprising an
input reflector receiving the light rays, and an output
reflector restoring the light rays to him. Depending on
the type of periscope, the path of the light rays
20'~24~
between the two reflectors may be direct or may undergo
one or more reflections.
The daytime channel provides for optimum vision as
long as there is sufficient lighting. However, it does
not allow night-time driving. For it is not possible,
at least in combat position, to use lighting means
integrated into the vehicle. It is therefore necessary
to use an electronic night-time channel including, for
example, an objective, a light intensifier tube and an
eyepiece.
To pass from one mode of vision to the other,
therefore, it is necessary to change the periscopes.
This dismounting and re-assembling operation is highly
detrimental to the armored vehicle which is thereby
completely deprived of vision for a few minutes. It is
then highly vulnerable and, to avoid any risk, it has
to withdraw and conceal itself while the periscopes are
being changed.
Another problem posed by this technique is that of
storing the periscope, when it is not being used, in
the cabin of the vehicle wherein the space is most
often very limited. Moreover, this periscope, when not
in use, runs heavy risks of being damaged if it is not
properl~ secured.
Besides, the periscope-changing operation entails
a locali~ed loss of imperviousness. In particular, the
vehicle is then not protected against nuclear,
bacteriological and chemical risk. More generally, the
xo~ 9
successive operations of dismounting and re-assembly
may modify the conditions of imperviousness, notably
through the wearing out of the joints.
The use of two independent periscopes for daytime
and night-time use also raises problems during periods
of intermediate lighting, for example at dawn and dusk,
or when certain zones are illuminated and others are
not illuminated. The substantial amount of time taken
to change from one mode of vision to the other means
that the observer cannot remain constantly in the
optimum conditions of vision.
To do away with the need for this changing
operation, day-and-night periscopes have been designed.
These periscopes include, in one and the same pack, a
standard daytime channel and a night-time channel with
light intensifier. Thus, the French patent applications
85 02575 and 85 02576 filed on 22.02.1985 present
substantially parallel daytime and night-time channels
wherein the input reflector is movable and directs the
light rays towards either of the two channels,
depending on the position selected by the driver.
These day-and-night periscopes solve a lot of the
pro~lems raised by the changing of the periscopes.
However, other problems appear. The hole drilled in the
armor, for the periscope, has to be big enough to
enable the passage of both channels and of the means to
control the movable reflector. Now, this hole is
clearly a vulnerable part of the armor and should
4 2042419
therefore be reduced to the maximum extent. The
presence of movable elements outside the armor is also
a factor of vulnerability. Besides, such periscopes
cannot be installed, as replacements, in vehicles that
do not have a daytime periscope because the existing
holes in the armor of such vehicles are too small.
SUMMARY OF THE INVENTION
It is an aim of the invention to overcome the
drawbacks of the prior art.
More precisely, an aim of the invention is to
provide a day-and-night periscope requiring as
small-sized a hole as possible drilled in the armor
and, in particular, a hole with a size similar to that
needed for the passage of a single daytime periscope.
A particular aim of the invention is to provide a
day-and-night periscope providing for maximum
imperviousness at the armor.
Another aim of the invention is to provide an
periscope such as this, having no moving parts outside
the armor and, more generally, having few moving parts.
Another aim of the invention is to provide an
periscope such as this, occupying as restricted a
v~lume as possible, so that it can be installed in many
different vehicles while, at the same time, ieaving
enough free space for the driver. For, the space
available for an periscope, for example in a tank, ~s
very limited. Notably, the following features have to
be taken into account: above the armor, the passage of
Z04~4~ 9
the turret and of the protection straps and, below the
armor, the proximity of the steering wheel, the
configuration and open position of thP door, the
driving position of the driver in the "head outside"
configuration, etc.
More generally, the periscope is also aimed at
meeting ergonomic constraints, both as regards the
positioning of the output prism of the daytime channel
and the eyepiece of the night-time channel and as
regards the means for switching from one channel to the
other.
Another aim of the invention is to provide a
s~andard optic periscope and, furthermore, electronic
displ~y means capable of including a light intensifier,
optic fibers, a CCD sensor, a heat camera etc.
These aims, as well as others that shall appear
here below, are achieved, according to the invention,
by means of a multiple-function periscope, notably for
armored vehicles, of the type including a
reflector-based optic vision device and at least one
electronic display device, for example for night-time
vision, comprising, between the input reflector and the
output reflector of said optic vision device,
reflection means movable between two extreme positions,
the first position enabling the free movement of the
light rays between said input and output reflectors and
the second position prompting the deflection of said
light rays towards electronic processing means.
20424~9
Advantageously, the periscope is of the type going
through the armor of said vehicle, only the input
reflector of said optic vision device being external to
said vehicle.
Thus the part of the periscope external to the
vehicle is reduced to the maximum extent, and is
identical to the emerging part in the case of a simple
daytime periscope. It does not pose any particular
problems of imperviousnes~, a~d can be easily adapted
to existing vehicles. The movable part is limited, and
is located within the vehicle, beneath the armor.
Preferably, said movable reflection means include
a mirror, held by a movable strap, and means for
guiding said strap between said extreme positions.
The movable strap is configured so as not to
interfere with the light rays, irrespectively of its
position.
In an advantageous embodiment, said guiding means
include a set comprising at least one link-rod,
~ positioned so as to provide a minimum horizontal and
vertical clearance for said mirror during its travel
between said extreme positions.
For, it is important to reduce the clearance of
the movable parts so as to minimize the overall space
Z5 occupied ~y the periscope.
Preferably, said electronic display device has a
wide-aperture lens having a bend of about 90~ in the
7 20~2419
vicinity of the image and downline with respect to said
image.
This enables the space factor to be further
reduced. Moreover, it is thus possible to reduce the
total length of the electronic channel and, hence, to
place the eyepiece or display screen of this channel
just below the output reflector of the daytime channel,
thus providing excellent visual comfort for the
observer.
Advantageously, said objective includes a set of
lenses with multilayer treatment and a prism.
Preferably, the hypoteneuse of sald prism is
treated so as to improve the transmission balance of
said objective, by at least one of the following
treatments:
- silver-coating
- improved aluminium-coating;
- multidielectric treatment optimized for a mean
incidence of 45~.
In an advantageous embodiment, said objective
includes a field glass between said prism and said
electronic processing means, the concave face of said
field glass being provided with multilayer treatment.
In a particular embodiment of the invention, said
objective has an aperture of about F/1, a pa~axial
focal length of 26 mm, an object field of about 45 and
an image field with a diameter of about 20 mm.
204Z419
Advantageously, said objective has a widened
useful spectral band, ranging from about 450 nm to 900
nm .
To facilitate passing from one channel to the
other, the periscope advantageously includes means to
contro~ the passage of said reflection means from one
of said extreme positions to the other, said control
means jointly putting said electronic processing means
into operation or out of operation.
In one particular embodiment of the invention,
enabling daytime and night-time vision, said electronic
display device is a light intensification channel,
including a wide-aperture objective, an intensifier
tube and a binocular optic system.
In another embodiment of the invention, said
movable reflection means include a reflector, for
example of the triangular-sectioned reflecting prism
type, fixedly joined to said objective, the assembly
formed by the movable reflection means and the
objective being capable of pivoting about an axis
substantially perpendicular to the plane defined by
said assembly. This requires an increase in the width
of the periscope but enables the night vision field to
be increased by the use of a prism with a hi~h index.
9 20~2419
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the invention
shall appear from the following description of a
preferred embodiment of the invention, given by way of
a non-restrictive illustration, and from the appended
drawings, wherein:
- Figures 1 and 2 show sectional views of a
day-and-night periscope according to the invention,
respectively in the daytime vision position and in the
night-time vision position;
- Figure 3 is a drawing of a bent wide-angle
objective, as used in the periscopes of figures 1 and
2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The embodiment described here below specifically
concerns a day-and-night periscope, the night-time
channel of which includes a light intensifier tube.
Kowever, it is clear that the invention can be
applied to other means for the processing of light
rays. Thus the light waves deflected by the movable
mirror may be received by a camera objective, the image
being restored on a display screen.
The drawing of figure 1 shows a day-and-night
periscope, notably designed for armored vehicles such
as tanks.
This periscope has a pac~ 10, containing the two
channels, namely the da~time and night-time channels.
The pack has an upper part 11, external to the armor 12
~o'~ 9
of the vehicle and closed by a port 13. This port 13
may include de-icing means, for example, through a
conductive, anti-reflective interference treatment or a
resistive silk-screen printing.
The part 11 external to the armor has a fixed,
single reflector 14, common to the daytime and
night-time channels, which is advantageously a
triangular-sectioned prism with total reflection or one
where the hypoteneuse has received a reflective
treatment (aluminium-coating, silver-coating or
dielectric treatment). This reflector may also be a
mirror.
The prism 14 is bonded to a generally
parallelepiped-shaped prism 15 going through the armor
12. The prisms 14 and 15 may also form a single prism.
It will be noted that the external and crossing
parts comprise only fixed optic means, identical to
those existing in the simple daytime periscopes. This
provides for perfect interchangeability of equipment,
the only condition being that the package should not be
too ~ulky. Such an periscope may there~ore replace
daytime periscopes in most existing armored vehicles
without any problems.
The lower part of the pack 10, beneath the armor
12, includes additional daytime and night-time
channels, and means for switching over from one channel
to the other.
11 ~0424~ 9
The daytime channel includes, in addition to the
prisms 14 and 15, an output reflector 16 which may
advantageously be a triangular~sectioned prism that
directs the light rays 17A towards the driver 18. This
prism 16 may be a total reflection prism, or a prism
the hypoteneuse of which has received a reflective
processing (aluminium-coating, silver-coating or
dielectric processing).
A parallelepiped-shaped prism 19 is bonded to this
triangular prism 16. The two parallelepiped-shaped
prisms 15 and 19 are separated by a space 20 in which a
retractable mirror 21 may be placed. The prisms 16 and
19 may also constitute a single prism.
Thus, in daytime vision, the light rays 17
successively go through a ~irst prism 14, a first
parallelepiped-shaped prism 15, an air space 20, a
second parallelepiped-shaped prism 19 and a second
prism 16.
The image seen by the driver 18 is substantially
equivalent to that obtained by a standard periscope,
with a single parallelepiped-shaped prism, without an
air space 20. For, this space 20, with a small width,
does not bring about any su~stantial field reduction,
it being possible to co~pensate for this reduction by
using a higher index than usual for these p-isms, for
example an index of 1.62.
12 20~z4~ 9
It is clear that, in another embodiment, the
daytime channel may be more complex and may include,
for example, more than two deflections of light rays.
In the daytime vision position, the retractable
mirror 21 is housed substantially in parallel to tke
prism 19, in a space 22 prepared for this purpose.
This mirror is maintained by a strap 23, movable
about an axis 24.
The strap 23 is shaped in such a way that it does
not affect the path of the light rays. The position of
the axis 24 has been chosen with precision, so that the
shifting of the mirxor 21 calls for a minimum
horizontal and vertical clearance, thus enabling the
greatest possible reduction in the space 20 between the
two prisms 15 and 19, and in the space 22 for the
housing of the mirror in the daytime position.
The switching over from one channel to the other
one is done by a lever 25 c~pable of pivoting by one
half turn. The top position of the lever corresponds to
the daytime channel and the bottom position ~figure 2)
to the night-time channel.
This lever 25 draws along, around its axis, a
link-rod 26 on which there is eccentrically fixed a
first end of a link-rod 27, the second end of which is
fixed to the mirror-holding strap 23.
A downward hal~-turn of the handle therefore makes
the mirror 21 pass from the daytime position (figure 1)
to the night-time ~osition (figure 2). Conversely, the
20424~ 9
13
return of the lever 25 to the top position causes the
return to the daytime position.
The passing of the lever 25 to the bottom position
automatically turns on the electronic processing means
such as a light intensifier tube, for example by means
of a switch actuated by a cam fixedly joined to the
lever,. Thus, in a single command, the driver goes from
the daytime channel to the night-time channel.
Conversely, the return to the daytime channel causes
these electronic means to go off.
Another way of carrying out the day/night
switching operation is to have the mirror 21 fixedly
joined to the objective 28 and to make the assembly
formed by the objective 28 and the mirror 21 rotate on
an axis 31 so tha$, for example by a 90' rotation, the
space between the prisms 15 and 19 is cleared to enable
daytime vision.
The mirror 21 may then be replaced by a
triangular-sectioned reflecting prism.
This configuration makes it necessary to increase
the width of the periscope but, notably through a use
of a prism with a high index replacing the mirror 21,
it enables an increase in the field of night-time
vision.
Figure 2 shows the periscope of the invention in
night-time position. The retractable mirror 21 is then
placed between the two parallelepiped-shaped prisms lS
14 ~0~'2419
and 19, in the air space 20, so as to direct the light
rays 17B towards a wide-aperture objective 28.
It must be noted that the input prisms 14 and 15
are common to both the daytime channel and the
night-time channel.
In the preferred embodiment described, the
night-time channel is a light intensification channel.
Advantageously, the objective 28 is a bent
objective, as described more precisely further below,
in relation to figure 3.
This bent objective enables the light intensifier
tube 29, necessary for night-time vision, to be
positioned high enough in the pack 10 for the eyepiece
30, in which the image 17 is formed, to be placed in
the vicinity of the output prism 16, so as to provide
for the visual comfort of the driver 18.
The intensifier tube 29 may be of any commercially
available type. Advantageously, it is a second
generation tube with electrostatic focusing and wafer
of microchannels such as, for example, the tube TH9311
marketed by THOMSON-CSF (registered name), the tube
XX1380, marketed by P~ILIPS (registered name), or the
tube MX9644/ W , marketed notably by THOMSON-CSF
(registered name).
The eyepiece 30 is advantageously a binocular
device, capable of presenting, for example, an output
pupil with a diameter of about 80 mm, so as to give
great comfort of observation. This binocular device,
20~2419
with an apparent field of the order of 45 ,
corresponding to a 45 object field of the night time
channel, for an overall enlargement of about 1.
The binocular device 30 may be directly coupled to
the intensifier tube 29, in taking up the image given
on the screen of this tube. However, to simplify the
binocular device or increase viewing comfort, this
coupling may be done by means of an enlarging optic
fiber making it possible, for e~ample, to go from a
tube 29 screen diameter to a greater binocular input
diameter, for example a diameter of 40 mm.
The use of an optic fiber independent of the
intensifier tube makes it possible to give the output
face of the fiber a slight curvature so as to improve
the quality of the binocular device 30 and, notably,
the field curvature.
The binocular device 30 may also be fitted out
with de-misting means, such as a heating resistor
placed in the eyepiece, or a conductive, interfering
treatment deposited on one face of the eye lens of the
binocular device, the temperature of which is regulated
by thermostat at about 35.
The bent objective 28 enables a substantial
reduction in the overall space fac~or of the periscope.
Figure 3 shows a particular em~odiment of an objective
such as this.
It is an objective with a wide aperture, of the
order of F/1, bent at 90- in the vicinity of the image.
16 ~04Z4~9
The useful spectral band covers a widened spectrum,
corresponding to the visible and to the near infra-red
ranges. This useful spectral band ranges from 450 to
900 nm.
This objective enables an image of an object or
scene, located between infinity and ten meters, to be
formed on the photocathode of the image intensifier
tube 29.
The 90 bend is made by a prism 41, with 21 mm
sides. This prism 41 is integrated into the optical
system which also includes six lenses 42 to 47 and a
field lens 50.
This optical system can be used to obtain the
following optical characteristics:
- paraxial focal length : 26.2 mm;
- aperture : F/1.0
- obiect field : 45
- image field : dia. 20 mm (which
corresponds to a
field edge
distortion of -7.3%)
Table I presents all the diopters used in this
objective, and gives their thicknesses, radii, indices
and useful diameters.
25The distance 4~ between the optic axis and the
intensifier tube is equal to 15 mm, and the length 49
from the front of the objective to the axis is smaller
than 51 mm.
17 2042~9
The maximum useful diameter is 26.2 in front, at
the pupil, and gets reduced to less than 25 mm in the
zone located above the tube.
The treatment used for the six lenses 41 to 47 are
multilayers, optimized for the high indices. The
glasses used have negligible absorption above 450 mm,
given the small thickness crossed.
The transmission is thus greater than 90%
throughout the 450 nm - 850 nm spectral band for the
objective alone.
The prism 41 undergoes the same multilayer
treat~ent on its input and output faces. The
hypoteneuse of the prism cannot work in total
reflection, owing to the substantial aperture. It is
therefore necessary to use a highly efficient treatment
so as not to penalize the overall transmission balance.
It is possible, in particular, to use one of the
following types of treatment: silver-coating, improved
aluminium-coating or multidielectric treatment
optimized fo~ a mean incidence of 45 .
Between the prism 41 and the photocathode of the
light intensifier tube 29, the objective also includes
a field glass 50 bonded to the intensifier tube. The
concave face of this field glass 50 is a~so given a
multilayer treatment. The plane face is left bare
because of the bonding.
As has already been stated here above, the device
for the electronic processing of the light rays is not
20424~9
18
limited to a light intensifier. It may be constituted,
for example, by any type of camera sensor, enabling a
display on a television type screen, and particularly
on a flat panel. It is possible, notably, to use
high-performance low light level CCD sensors or an
assembly constituted by an intensifier tube coupled (by
optic fiber for example) to a CCD sensor. In this case,
it is possible to use several screens so that, for
example, other passengers of the armored vehicle can
also observe the exterior. Besides, it is also possible
to envisage the use of images coming from other sensors
such as distance cameras, heat cameras and complex
information, such as maps, by day and by night.
In a particular embodiment of the invention, it is
possible for the retractable mirror to take one or more
intermediate positions between the two extreme
positions, so as to direct the light rays towards
several distinct electronic devices.
19 2 0 4 2 43i9
T~U3L~E I
_
THICXNESS RADIUS INDEX USEFUL DIAMETER
1 37.935 26.20 0.00
4.088 1.721
2 282.080 25.60 0.00
4.664 1.000
3 -4~.741 24.30 0.00
9 903 1.667
4 -29.6æ 23.90 0.00
1.074 1.000
-26.065 23.20 0.00
1.624 1.667
6 35550 23.20 0.00
7 2.851 36.329 1.000 25.80 0.00
6.276 1.783
8 -42 028 24.70 0.00
.202 1.000
9 26.363 23.60 0.00
6.994 _ 1.709 22.90 0.00
1.949 1.905
.700 l.OOD 22.00 0.00
12 O 000 22.00 x 21.00
21.000 1.871
3.370 20.00 x 19.00
14 1.134 -18.173 1.667 19.00 0.00
0.000 20.00 0.00
- 1.000
_
