Wide angled trapezoidal periscope

A wide angle trapezoidal periscope is disclosed having an upper trapezoidal housing and a smaller lower trapezoidal housing secured to said upper housing having optics sealed therein which include parallel upper and lower windows and parallel upper and lower mirrors. When used on military vehicles, the lower trapezoidal periscope housings are inserted within evenly and closely spaced trapezoidal openings in the rim of a hatch and are secured to the hatch with corner connectors to clamp non-parallel walls of said upper housings within about 1/8 of an inch of the adjacent non-parallel walls of the next adjacent trapezoidal housing. Each periscope provides a vertical field of view of about 43.degree. and a horizontal field of view of about 140.degree..

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention pertains to trapezoidal wide angle periscopes for 
military vehicles or the like, and more particularly relates to a 
trapezoidal periscope which provides improved vision, laser protection, 
improved ballistic protection, improved sealing against rain and nuclear, 
biological and chemical agents, and are easily installed. 
2. Description of the Prior Art 
In general, observation for the crew of a combat vehicle is normally 
provided by vision blocks, or for more heavily armored vehicles, by 
periscopes. These prior art periscopes normally have a rectangular cross 
section, and are installed around the periphery of a hatch (see prior art 
FIG. 21A). They are usually designed to be installed from inside the 
vehicle. The rectangular cross section and interior mounting fasteners 
between periscopes prevent the periscopes from being nested close together 
thus restricting the horizontal field of view. 
Assignee's Garber U.S. Pat. No. 4,275,639 and Lykam U.S. Pat. No. 3,309,962 
disclose the location of other types of periscope on military vehicles. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the trapezoidal periscope of the 
present invention is designed to include the following features and 
advantages: 
1. The periscope includes an exterior head portion that is larger than its 
interior body portion which provides improved vision and helps prevent the 
periscope from being blown into the vehicle by an overhead explosion. 
2. The periscope is designed to be installed on the outside of a hatch 
cover rather than around the periphery of the hatch opening as used in 
certain prior art devices thereby improving the field of view by placing 
the periscope closer to the crew members eyes while maintaining an 
adequate hatch opening. Military standards require a minimum circular 
opening of 22" diameter with 28" diameter being preferred. This feature 
improves the crew's protection when viewing from a popped hatch cover, and 
also makes it unnecessary for the crew members to change the position of 
their body and their seat when changing from closed hatch cover, to popped 
open hatch cover operation. 
3. The periscope is attached to the vehicle with corner clamps to minimize 
the space between periscopes and to provide flexibility of mounting. 
4. The periscope seals on the exterior of the vehicle so as to be self 
draining and to prevent trapping of nuclear, biological and chemical 
agents, and rain or other liquids. 
5. The exterior or upper periscope housing forms a small overhanging 
horizontal visor to protect the exterior window from rain and falling 
objects. The exterior window is glass to prevent it from being scratched 
when cleaned. 
6. The interior or lower window is a hard coated plastic which provides 
limited scratch resistance while eliminating the possibility of glass 
fragments being propelled into a crew member's eyes by a ballistic impact 
into the periscope. 
7. The interior and exterior windows are parallel to prevent distortion of 
the scene being viewed, but are not vertical. The exterior window is 
tilted toward the ground to further protect the glass and to improve the 
vehicle concealment. The overhanging visor and tilting of the exterior 
window reduces the likelihood of sunlight reflecting from the exterior 
window. When the sunlight is so low that it directly hits the exterior 
window, the tilt of the glass directs the reflection downwardly toward the 
vehicle roof or ground instead of toward the enemy. 
8. The exterior glass window includes a laser filter that protects the 
crew's eyesight from low to moderate intensity lasers that may appear on 
future battlefields. 
9. The interior of the periscope contains a horizontal spacer of 
transparent polycarbonate that prevents ballistic fragments and shock 
waves from entering the vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The wide angle trapezoidal periscopes 20 (FIGS. 1-4) of the present 
invention are illustrated as being used on a military vehicle V in both 
the driver's hatch cover 22 and the commander's hatch cover 24. As 
illustrated, five periscopes are used in the driver's hatch cover while 
the commander's hatch cover has eight periscopes to provide 360.degree. of 
viewing through the several periscopes. Each hatch cover includes a dome 
for receiving the operator's head and a rim for receiving the trapezoidal 
periscopes. 
Although the wide angle periscopes 20 have been illustrated as being used 
on a military vehicle, it will be understood that the periscopes may be 
used in other environments, military or civil. For example, the periscopes 
may be used on bomb shelters, prison observation towers, and other 
civilian endeavors when it is important to visually observe tests or the 
like which may cause injury to personnel. 
When used on military vehicles V, each periscope 20 includes an upper armor 
trapezoidal housing 26 (FIGS. 3-5) and a lower trapezoidal housing 28. The 
lower housing is smaller than the upper housing and extends through 
trapezoidal openings 29 in the associated hatches 22 and 24. 
The upper housing 26 is presently formed as a precision casting of high 
strength aluminum such as A-356.0-T6 or A-357.0-T6. The upper housing can 
easily be precisioned cast from ballistic armor steel for a higher level 
of overhead ballistic protection, eliminating the need for any additional 
ballistic covers to be added. The upper housing 26 includes an upper 
generally horizontal visor 30 with upper side wings 32 which protect an 
upper glass window 34 from rain and falling objects. A window opening 36 
is defined by an upper lip 38 which communicates with side lips 40 and a 
portion of a bottom or rim flange 42 which cooperate to maintain the glass 
window 34 within the upper housing 26. The rim 42 extends around the front 
and rear of the lower periphery of the upper housing and includes beveled 
inner edges 44 (FIG. 4). As shown in FIG. 12A, the non-parallel side walls 
35 (only one being shown) of the upper trapezoidal housing 26 do not 
include outwardly projecting bottom rims, such as the rims 42 of the 
parallel walls of the upper trapezoidal housing 26 thus permitting 
adjacent non-parallel walls of adjacent upper housing to be placed very 
close together as illustrated in FIG. 2. 
An upper shock pad 46 (FIGS. 4 and 5) conforms to the shape of a rear wall 
48 of the upper housing and includes a self-stick adhesive on one side for 
bonding to the inner surface of the rear wall 48. 
An upper periscope body 50 (FIGS. 4-10) is formed from transparent 
methacryolate plastic, Type I or II grade A or C, Specification L-P-391 or 
optical specification MIL-P-8184. All surfaces are polished to military 
specification MIL-0-13830, quality 80-50 except non-optical edges around 
the periphery of the upper periscope body. These non-optical surfaces of 
the upper transparent periscope body 50, the upper window 34, and an upper 
mirror 52 are glass bead blasted to a matte finish and are painted black 
with MIL-C-4616A paint. Also, all optical surfaces are polished, the 
optical surface flatness is within four wave lengths of 632 nm over any 
square inch portion, and with the clear aperture to be within 0.020 inches 
of all edges. 
The peripheral edges of an upper mirror 52 and the upper window 34 are 
bonded to the upper periscope body 50. The upper window 34 is formed from 
a tempered laser filter glass, heat absorbing type, with an optical 
density of about 3.0 at 1.06 microns. The filter meets medium intensity 
requirements for distortion and waves. The upper mirror 52 is formed from 
Type I, class I, optical glass with silvering qualities which conform to 
specification DD-451.125. The surface polish should satisfy specifications 
MIL-0-13830, quality 80-50. The surface is aluminized in accordance with 
military specification MIL-M-13508. The clear aperture is within 0.020 
inches of all edges. The upper transparent body 50, the upper mirror 52, 
and the upper window 34 are then inserted in the upper housing 26 
preferably while the upper housing is inverted. 
The lower trapezoidal housing 28 (FIGS. 4 and 5) is smaller than the upper 
housing 26 and is cast from the same type of aluminum armor material as 
the upper housing 26. The lower housing 28 includes an upper rim 60 having 
a beveled surface 62 which mates with the beveled inner edge 44 of the 
bottom flange 42 of the upper trapezoidal housing 26 to seal the two 
housings together when assembled as shown in FIG. 4. 
Each lower trapezoidal housing 28 is shaped in vertical cross section as 
illustrated in FIG. 4, with FIG. 5 illustrating the trapezoidal shape. 
Each lower housing 28 includes a lower window opening 65 defined by upright 
side edges 66 (only one being shown) an upper edge 68 and a lower edge 70 
(FIG. 4). A lower shock pad 72 is slitted at 73 to conform to the shape 
of, and is bonded to, an inclined bottom wall 74 of the lower housing 28 
by self-stick adhesive. 
A lower optical periscope body 76 (FIGS. 4-10) is formed from transparent 
plastic of the same type and grade as that of the upper periscope body 50 
and is surface polished to the same specifications as stated in regard to 
the upper periscope body. The narrow non-optical edges of the lower 
periscope body 76 are treated in the same way as equivalent surfaces of 
the upper body. 
The upper surface of the lower optical periscope body 76 is shaped in the 
form of a trapezoid as illustrated in FIG. 5 with the upright side walls 
78 being of generally V-shape with a notch 80 formed in the major portion 
of the outer surface for receiving a lower periscope window 82. 
The lower window 82 is formed from the same type of plastic as that used in 
the upper body 50 and lower body 76, and the non-optical edges of the 
window are bonded in the notch 80 in the position shown in FIG. 4. The 
outer surface of the lower plastic window is coated with an abrasive 
resistant coating to prevent optical damage to the lower plastic window. 
A lower mirror 84 is formed from the same type of glass and conforms to the 
same specification as that given in regard to the upper mirror 52. The 
peripheral edges of the mirror 84 are bonded to the body 76. 
A ballistic spacer 86 is formed from polycarbonate plastic of premium 
optical grade, ultra violet stabilized. All optical surfaces are polished 
in accordance with the same specifications as that used in regard to the 
upper periscope body 50. The lower periscope edges of the ballistic spacer 
86 are bonded to the upper portion of the lower periscope body by 
transparent adhesive. 
The lower periscope body 76 with the lower window 82, lower mirror 84 and 
ballistic spacer 86 bonded thereto is lowered as a unit into the lower 
housing 28 and comes to rest against the lower resilient pad 72 (FIGS. 4 
and 5). The upper housing 26 receives the upper body 50, upper window 34, 
and upper mirror 52 when bonded together as a unit as previously 
described. The two housings are then moved together with the beveled 
surfaces 44 of the upper flange 42 firmly but releasably engaging the 
beveled surface 62 of the bottom rim 60 thereby removably connecting the 
upper housing 26 and lower housing 28 firmly together. 
FIGS. 6-10 also better illustrate the shapes, including certain bevel cuts, 
in the upper optical body 50 when the upper window 34 and upper mirror 52 
are bonded thereto; and to illustrate the lower optical body 76 with the 
lower window 82, lower mirror 84 and ballistic spacer 86 bonded thereto. 
The windows, mirrors and ballistic spacers are illustrated as being spaced 
from their associated periscope bodies for clarity. It will be understood, 
however, that the peripheral edges of the several optics are bonded to 
their associated bodies. The spacing for the edge bonding material (not 
shown) is only about 0.050 of an inch. As used in the specification and 
claims, the optics of each wide angle trapezoidal periscope 20 includes 
the upper window 34 (FIGS. 4 and 11) in the upper housing 26, which upper 
window is the furthest from the observer's eyes (FIGS. 20 and 21) and is 
thus the front and the widest optical component in the periscope 20. As 
illustrated in FIG. 9, the widest portion of the preferred upper window 34 
and the upper periscope body 50 is 8.88 inches; while the thickest portion 
of the upper window 34 and the upper periscope body 50 is 2.77 inches. The 
lower window 82 is the closest to the observer's eyes (FIGS. 20 and 21) 
and is the narrowest optical component in the lower periscope body 76 
which is the lowest portion of the lowest window 82 (FIGS. 5, 6 and 8). 
The thinnest optical components include the lower end of the lower window 
82, and the lower end of the lower mirror 84 which form a very narrow 
lower edge as illustrated in FIG. 6. 
FIG. 10 also illustrates, in section, the position of the upper housing 26 
and lower housing 28 at the widest or front portion of the optical 
assemblies. 
Having reference to FIGS. 11-15, it will be noted that reference lines A 
and B indicate the narrowest transverse width of each trapezoidal opening 
29 (FIGS. 3 and 4) in the driver's hatch cover 22, and similar openings in 
the commander's hatch cover 24. It will also be noted that the upper 
outward portion of the lower housing 28 below the rim 42 (FIG. 4) is 
considerably wider than the distance between reference lines A and B. 
Thus, in order to insert the lower housing 28, which has a trapezoidal 
gasket 101 fitted thereon, into the trapezoidal opening 29, the 
trapezoidal periscope must be moved downwardly and outwardly into the 
trapezoidal opening 29 from above the hatch covers 22 or 24 in the 
direction indicated by arrow C, FIG. 14, with the wide portion of the 
lower housing 28 closely adjacent to an outer wall 102 of the trapezoidal 
opening 29. When placed in operative position as shown in FIG. 4, the 
upper peripheral surfaces of the lower trapezoidal housing 28 and gasket 
101 are snugly fitted relative to the peripheral edges of the trapezoidal 
opening 29. 
As illustrated in FIGS. 2 and 4, a plurality of rim clamps 106 are provided 
for clamping the four corners of the rims 42 of the upper periscope 
housings 26 to the driver's hatch cover 22. As illustrated in FIGS. 16-19, 
each rim clamp 106 includes a capscrew 108 which extends through a 
cylindrical hole 110 (FIG. 19) in a one piece rim clinching body 112 
having a tapered lower end portion 113 connected to an annulus 114 having 
a pointed end 116 which is received between two adjacent rims 42 (FIG. 16) 
of the upper trapezoidal housing 26 to prevent rotation of the body 112 
when the capscrew is being tightened or loosened. An enlarged arcuate rim 
clinching flange 118 includes a flat lower rim engaging surface which 
extends about 190.degree. about its axis. The outer periphery of the 
arcuate flange 118 is beveled and a portion thereof is received in arcuate 
grooves 120 (FIGS. 5 and 16) in the outer wall of the upper periscope 
housing 26 for accurately positioning the periscopes when the capscrews 
are tightened. Tightening of the four capscrews 108 associated with each 
trapezoidal periscope 20 partially flattens the gasket 101 (FIG. 4) around 
the trapezoidal holes 29 in the associated driver's hatch cover 22 (FIG. 
1) or commander's hatch cover 24 thereby providing a fluid tight seal 
preventing rain water and nuclear, biological and chemical contaminates 
from entering the vehicle V. It will also be noted that when the capscrews 
are fully tightened the entire periphery of the upper housing 26 comes in 
contact with the mounting surface around the trapezoidal holes 29, 
allowing the capscrews to be fully torqued without over compression of the 
gasket 101. This feature protects the gasket 101 from outside 
environmental damage. 
The vertical field of view of the trapezoidal periscope 20 of the present 
invention is illustrated in FIG. 20 for different positions of the 
commander's head and eyes, three different eye positions being 
illustrated. 
When the commander's or operator's eyes are in the "normal eye" position 
the line of sight is illustrated by lines A,A' which provide a normal 
field of view between -10.degree.--12.1.degree. below the horizontal; and 
3.5-5.7 above the horizontal as indicated by lines B and B' when the 
vehicle V is horizontal thereby providing a normal 17.8.degree. field of 
view without moving the eyes out of the "normal eye" position. 
When the operator moves his eyes to the "low eye" position the line of 
sight is indicated by lines C and C' or between 22.5.degree. and 
16.25.degree. above the horizontal. When the operator's eyes are in the 
"up eye" position indicated by line D, the line of sight is -20.5.degree. 
below the horizontal. Thus, the total vertical field of view in response 
to the operator moving his head and eyes between the three above described 
positions is about 43.degree.. 
Although not illustrated, the total horizontal field of view using the 
trapezoidal periscope of the present invention is about 140.degree. when 
the maximum dimension of the optics are equal to or less than that 
illustrated on FIGS. 6, 7, 9, and 10. 
FIGS. 21 and 21A illustrate a prior art periscopes 130 (of the type 
discussed in the prior art section) each having a size that is similar to 
that of the trapezoidal periscope of the present invention except that the 
horizontal cross-section of the periscope is rectangular, not trapezoidal 
in shape. When viewing at "normal eye" level, lines N-1 and N-2 indicate 
that the maximum upward line of sight is 9.4.degree. and the maximum lower 
line of sight is -6.3.degree. below the horizontal. When viewing from the 
"low eye" position the line of sight is between 21.degree. and 
10.5.degree. above the horizontal as indicated by lines L-1 and L-2. When 
viewing from the "up eye" position, the lines of sight are between -10.5 
and -12.6.degree. below the horizontal as indicated by lines U-1 and U-2. 
Thus, the total vertical field of view is 33.6.degree. with the prior art 
periscope 130 as compared to 43.degree. with the trapezoidal periscope 20 
of the present invention. 
The horizontal field of view of the prior art periscope is between 
94.degree. and 104.degree. as compared to 140.degree. of the trapezoidal 
periscope of the present invention. 
FIG. 21A illustrates a portion of the top of a prior art military vehicle 
V2 showing a driver's hatch cover 22A in a relatively wide angle popped 
position of about 20.degree. with a plurality of prior art periscopes 130 
mounted in spaced rectangular opening in the roof R of the vehicle, not in 
the hatch cover 22A as in the present invention. 
FIGS. 22 and 23 illustrate the commander's hatch cover 24 of the present 
invention which includes a dome 132 of sufficient size to accommodate the 
commander's head. A substantially horizontal rim 134 has a plurality of 
equally spaced trapezoidal openings 29 therein, each of which receives one 
of the trapezoidal periscopes 20. A skirt 136 is integral with the rim 134 
and includes an annular resilient seal 138 (FIG. 23) which engages a ring 
140 secured to the body 142 of the vehicle V thereby providing a fluid 
tight seal against rain and nuclear, biological, and chemical gases. A 
conventional latch 144 is provided within the vehicle V to lock the hatch 
cover 24 in closed position. The hatch cover 24 is bolted to a pair of 
pivot arms 146 (FIGS. 22 and 23) which are rotatable about a generally 
horizontal axis X. One of the arms includes a slotted arcuate portion 148 
positioned to receive the free end of a spring loaded latch pin 150. A 
handle 152 is pivoted to the latch pin and the body 154 of a latch 
assembly 155 by a pivotal link 156. 
When it is desired to slightly open the hatch cover 24 (i.e., pop the hatch 
cover) the operator releases the hatch cover 144 allowing the forward end 
of the hatch cover to open about 7.degree. until the latch pin enters a 
first slot 158 allowing the operator to see forward without using the 
periscopes. The operator may lower the handle 152 to withdraw the pin 150 
from the first slot 158 and move the hatch to its fully open position at 
which time the pin 150 enters the second slot 160. When the prior art 
hatch 22A in the "popped" position as illustrated in FIG. 21A, the hatch 
cover 22A is opened about 20.degree.. 
Since the periscopes 20 of the present invention are mounted on the hatches 
cover 22 and 24 (FIG. 1) rather than the bodies of the vehicle, V, it is 
apparent that the angle at which the hatch cover of the present invention 
are opened when in the "popped" position is much less than that required 
when the periscopes are mounted on the upper wall of the vehicle V, as is 
conventional in the art, since the driver or commander must open the hatch 
cover sufficiently to see over the conventional periscopes. Thus, 
positioning the trapezoidal periscopes 20 on either hatch cover 22 or 24 
allows better protection for the driver and commander from small arms fire 
or the like and permits desirable circulation of air within vehicles which 
are not air conditioned. 
From the foregoing description it is apparent that the trapezoidal 
periscope of the present invention includes an upper trapezoidal housing 
which is larger in length, width, and height as compared to the lower 
housing. Since the lower trapezoidal housing is smaller than the upper 
housing a major portion of the lower housing is inserted within the 
associated trapezoidal opening in the rim of the driver's hatch cover or 
commander's hatch cover. The lower housing is sealed by a compressible 
trapezoidal gasket to the associated trapezoidal opening. Rim clamps are 
positioned to clamp against and accurately center the four corners of the 
upper housing with the associated trapezoidal opening permitting the 
trapezoidal sides of the adjacent wider upper housings to be within less 
than about 1/8th of an inch from adjacent upper housings thus permitting 
individual and quick removal and replacement of damaged periscopes from 
the top of the vehicle. Each upper housing window includes a laser filter 
and is angled about 10.degree. downwardly and inwardly from a vertical 
plane for minimizing reflection of sun light and laser beams for 
protecting the crew's eye sight. A transparent polycarbonate spacer in the 
periscope prevents ballistic fragments and shock waves from entering the 
vehicle, and an integral blackout cover is attached to the lower 
trapezoidal housing. 
Although the best mode contemplated for carrying out the present invention 
has been herein shown and described, it will be apparent that modification 
and variation may be made without departing from what is regarded to be 
the subject matter of the invention.