In combat, seconds count and a moment’s hesitation or distraction can mean the difference between life and death. So it's no small problem that modern riflescopes often require soldiers to look away from their targets or take their hands off their rifles in order to change magnification. Sandia National Laboratories’ Rapid Adaptive Zoom for Assault Rifles (RAZAR) riflescope is capable of switching between high and low zoom magnifications at the touch of a button, allowing soldiers to concentrate on the battle rather than their scopes.
Currently a prototype, RAZAR is the result of an eight-year development effort led by Army Special Forces officer turned optical engineer Brett Bagwell. Based on a US Department of Defense (DoD) need for a compact zoom riflescope that could change magnifications quickly, Sandia says the scope is not only easy to use, but rugged, lightweight, compact, and very energy efficient.
The key to RAZAR is Sandia’s “adaptive zoom” technology, which was invented by David Wick while he worked as an optical engineer for the laboratory. It differs from conventional zoom optics in that the lenses don’t move. In a regular scope, magnification is changed by having the optical components moving along the scope’s axis. That’s why telescopes extend and retract and automatic zoom cameras do their little dance when they focus.
In adaptive zoom, the optics act more like the human eye, where focus is controlled by muscles that change the shape of the lens. Adaptive zooms use glass lenses combined with polymer lenses made of two flexible, hermetically-sealed membranes filled with a polymer fluid. An ultrasonic piezoelectric actuator electro-mechanically changes the lens curvature inside of 250 milliseconds and with an accuracy of 100 nanometers. This allows the scope to be compact, lightweight, and adjustable, while using very little power, with two AA batteries providing enough power to make 10,000 actuations.
Sandia says that though the principle is not new, the tolerances required much of the RAZAR technology to be developed from scratch. First invented in the late 19th century, adaptive lenses has previously been used for little more than cheap, adjustable spectacles for the developing world. One special problem Sandia faced was finding ways of manufacturing the polymer lenses that eliminated bubbles and other flaws that would affect the optical qualities.
Another feature of the adaptive zoom system is the “zero-power hold” feature, which, unlike camera-based zooms, maintains focus if the power is switched off. This means a RAZAR scope can still be used with dead batteries – although the focus can't be changed.
Sandia also sees the RAZAR technology has having applications in medical imaging, binoculars, hunter scopes, cell phones, security cameras, and other places where optical zoom is needed in a compact package. Bagwell is currently working on a night vision version of RAZAR and recently demonstrated an adaptive zoom that worked in the thermal infrared waveband.
The video below outlines the RAZAR adaptive zoom system.
Source: Sandia Labs
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