Many military vehicles in use today employ what is called an Integrated Commander's Weapon Sight (ICWS) (also referred to as an “Improved Commander's Weapon Station”. The commander in any armored military vehicle must maintain both situational awareness (visibility outside the vehicle) and safety inside the vehicle. Current ICWS Periscopes in use today typically consist of several common elements. These are:
Top Block
Bottom Block
Housing Cover
Reflective Top Minor
Sealing Adhesive
Main Housing
Viewing Window
Reflective Bottom Minor
Top Gap
Bottom Gap
Laser Filter
Optical Adhesive
Plate Armor
The top and bottom blocks make up most of the volume of the complete assembly. They are typically made of glass. The top block serves as the entry point for the external incoming image. It has a mirrored back face that reflects the image and a bottom face that usually has a laser filter bonded to it with an optical adhesive to protect the commander from harmful wavelengths of light. The bottom block also has a mirrored back face to again reflect the incoming image to an exit face on the bottom block. Another typical feature in the optical path is a polycarbonate window which is used to help prevent any blowout of glass should a projectile travel through the unit and shatter both pieces of glass. The rest of the assembly is usually composed of adhesives and housings that hold it all together; along with a ballistic guard which is an armored plate of sorts, designed to prevent projectile fragments from penetrating the interior of the vehicle should they succeed in penetrating the top block.
Two primary weaknesses are prevalent among existing ICWS Periscopes on the market: 1) leakage that affects visibility; and 2) safety issues. Pertaining to the former, existing designs employ an air gap positioned between the laser filter and the bottom block. A standoff is usually placed between the top and bottom blocks of glass to form this gap. The purpose of the gap was purportedly to reduce the “shock”, or transfer of energy, from one block to the other if a projectile fragment entered the top block. The problem this created, however, was that the device no longer was “leak proof”, and any moisture that enters the periscope and resides in that gap will cause a drastic reduction in optical performance of the periscope, thus hindering the commander's visibility. As regards the latter, as weapons become more powerful with technological advances, the use of glass to form the top and bottom blocks is no longer considered safe. The glass employed in existing designs was never intended to deal with high velocity and high trajectory projectiles. The armored plate has been the only mechanism currently in use to serve this purpose. What is needed are new materials and structural changes to existing designs to improve ICWS Periscopes of the future for greater effectiveness and safety.