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Unlike
light amplifiers, IR detectors can “see” targets in total
darkness or when they have bright lights behind them. They can even see
through smoke and, to a lesser degree, fog (moist air degrades IR energy).
A material that IR does not travel through well is glass. Hence, the lenses
of thermal imagers are made of the rare and very expensive metalloid germanium.
That’s one reason why even the more modest units cost in the $10,000
to $20,000 range.
Of course
there’s more to the technology than a lens, as a look at two HotEye
models will illustrate.The HotEye 3x is a six-pound handheld that has
the feel of a portable spotlight. It uses a ferroelectric IR sensor—sometimes
called second generation—to push a greenish 320- by 240-pixel image
to its four-inch LCD. It comes standard with a manually focused 50mm lens,
which yields an 18-degree horizontal field of view and can supposedly
detect a man at a distance of 1,600 feet. (It’s indicative of IR
imaging’s roots in military targeting and surveillance that “range
of human detection” is a standard unit of comparison.) The unit
also has two-to-one digital zoom, much like a video camera, which this
technology resembles much more than it does a monocular.
The
HotEye 109 is meant to be fixed on a cabin top or tuna tower and is encased
in a standard ACR 100 spotlight housing, using the ACR jog stick for pan
and tilt. This seems like a clever idea in terms of aesthetics and ease
of repair; D&B’s Gravely reports that he’s working on
a similar arrangement with the manufacturer of traditional chromed megayacht
spotlights.
The
model 109 uses a third-generation microbolometer IR sensor, small enough
to fit in the ACR case and also more solid-state and rugged. It only produces
a 160- by 120-pixel image, but Gravely says that its increased sensitivity
(.001 degree, 10 times better than that of the ferroelectric) more than
makes up for the decreased resolution. The unit outputs to a standard
NTSC video lead, and thus the user can feed the signal into any video-capable
monitor. It comes standard with a 100mm lens, nine-degree field of view,
and human detection to 2,800 feet. Both models sell for about $15,000,
and D&B can provide either with alternate lenses and other customization.
D&B
is a small company that has only been in existence for a couple of years,
but it has high hopes. Gravely acknowledges that Raytheon opened the door
to thermal imaging in the marine market a few years ago but eventually
dropped out; he thinks the key to success is targeting large boats with
a few good distributors who thoroughly understand the products. While
Raytheon’s Infrared division no longer builds marinized thermal
imaging units, it is responsible for the sensor in the HotEye 3x and is
busy in the currently active military and public safety markets. One might
hope that the growing use of the technology would drive manufacturing
costs downward, but there is the opposing dynamic of rare germanium.
Price
aside, thermal imaging appears to be another valuable electronic aid to
navigation. Gravely likes to refer to one of D&B’s favorite
customers, professional sportfishing captain Eddie Herbert, whose comments
are posted on the company’s Web site: “We have had a HotEye
on the new Reel Tight (80-foot Merritt) for four months now, and it has
already allowed me to navigate around debris and objects in the water
that our top-of-the-line [70-mile] radar couldn’t pick up. Just
the other evening we avoided a collision with a small 16- or 17-foot open
boat running at night without lights.”
If Herbert
is also using his HotEye to check out the ladies around the marina, he’s
not saying.
D&B
Technology Phone: (407) 647-7500. Fax: (407) 647-7505. www.hoteyenow.com.
ITT
Industries Phone: (800) 448-8678. Fax: (540) 362-4574. www.ittnightvision.com.
Ben
Ellison has been a delivery captain and navigation instructor for nearly
30 years and was recently the editor of Reed’s Nautical Almanacs.
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