ight and flight have gone together since the era of
Greek mythology, when Icarus flew too close to the
From the perspective of commercial jet passengers, many of
the optical applications in aviation are less than obvious—except
perhaps for the laser-powered bar-code reader at the boarding
gate. But photonics plays crucial roles behind the scenes.
Just as in ground-based telecommunications, optical fibers
are replacing copper wires in airplanes to reduce vehicle weight
and provide signals free from electromagnetic interference.
Ring laser gyroscopes keep the aircraft straight on course.
Modern display screens connected by optical fibers provide
diverse entertainment options for long-haul passengers. As
aircraft manufacturers seek to substitute composite materials
for aluminum and other metals, scientists are developing innovative new techniques—many involving lasers—to fabricate
airframe components.
This article provides a snapshot of several ways in which
lasers, fiber optics and related technologies will make civilian airplanes better over the next decade or so. It excludes the
security-screening applications in the airport terminal, as well
as scientific instruments that must be flown on aircraft, such as
lidar systems for remote sensing.
L
Head-up displays and head-worn displays
[ Head-up display ]
Combiner glass
Outside scene
Display
Magnifying lenses
Parallel rays of outside
scene plus display
Collimating lenses
Mirror
Cathode ray tube
Illustration by Phil Saunders
Sensors
Imaging sensors
Synthetic imagery
Head
position/head
tracker
Display/image
processing system
Camera capture
Illustration by Phil Saunders
HUD-equipped planes to conduct an approach to an airport
under lower-visibility conditions than what they would otherwise be allowed to do.
Typically, poor weather conditions cause aviation authorities to require planes to fly under “instrument flight rules,” or
IFRs, which for the casual pilot are significantly more complex
and require more training than “visual flight rules,” or VFRs,
which are intended for clear-sky conditions. At busy airports,
the imposition of IFRs may enable a lower “throughput”
of departures and arrivals because the planes must be more
widely spaced during takeoffs and landings than they are
under VFRs. One goal of U.S. aviation officials is to develop
technology for “equivalent visual operations,” meaning that
planes could land and take off at the same pace—and level of
safety—under IFRs as VFRs.
HUDs reduce the visual accommodation—the need to
refocus one’s eyes—necessary for pilots to move their eyes
