Maritime Public Safety
Thermal Imaging and the Maritime
Law Enforcement Operator
by: David Lee
as published in the Nov/Dec 2007 issue of Marine Tactical magazine
Introduction
Police boats will always play a role in enforcing laws and keeping the peace, but today’s
maritime law enforcement personnel do much more than that. With missions expanding,
and budgets shrinking, police boats find themselves involved in search and rescue missions,
basing SCUBA operations, conducting harbor safety patrols, assisting disabled boaters, and
even responding to HAZMAT emergencies.
These missions can happen any time, and in any weather. Day and night, in good
weather and bad, police boats need to be equipped to answer the call. By extending and
expanding the utility of these craft, maritime thermal imaging cameras have proven their
worth day in and day out, year after year.
Although their airborne counterparts are well acquainted with the benefits of thermal
imagers in the law enforcement role, the maritime police operator is often not. The
recreational boater has discovered the basic advantages of using FLIR thermal imagers
– simply being able to see at night and in bad weather provides an undeniable measure of
added safety to these mariners – the law enforcement boat operator, however, gets much
more far-reaching benefits from a maritime thermal imager.
Why go thermal? Because Nothing hides from a thermal imager
You can’t hide your heat. More precisely, you can’t hide your thermal energy. Everything
emits thermal energy – even ice cubes – night and day, in good weather and bad. By sensing
this thermal energy and displaying it as black and white TV video, thermal imagers allow you
to see things from farther away and with greater contrast than conventional visible-light
cameras and night-vision technologies, both of which require visible light to generate an
image. Thermal imagers, on the other hand, don’t require external lighting, can’t be fooled
by camouflage, and can see man-sized targets from farther away than comparable TV
cameras.
Quite simply, thermal imaging works when other technologies don’t. Thermal imaging
is ideally suited to any law enforcement application, because it requires no lighting and
provides superior threat detection day or night. Thermal imaging is the only technology that
provides true 24/7 capability.
How do these different technologies work?
Our eyes see reflected light. Daylight cameras, night-vision devices, and the human
eye all work on the same basic principle: light energy hits something and bounces off it, a
detector then receives it and turns it into an image. The ability of a given detector – be it
in an eyeball, or a camera – to create that image is directly related to the amount of light
available. At night there isn’t any sunlight to bounce off anything, so we’re limited to the light
provided by starlight, moonlight and artificial lights. If there isn’t enough, it’s hard to see.
Night vision devices – those greenish pictures we see in the movies and on TV – often
come from night vision goggles (NVGs). NVGs take in the small amount of visible light
available, magnify it greatly, and project that onto a display or an eyepiece. Unfortunately,
NVGs have the same sorts of limitations as the naked eye because the amount of visible
light available to them is limited; remember, the imaging performance of anything that relies
on reflected light energy is limited by the amount and strength of the light being reflected.
At sea on a cloudy night their utility goes down even more.
Thermal imagers help law enforcement
mariners navigate and operate safely at night.
Maritime Public Safety
Maritime Public Safety
Visible-light cameras – be they daylight cameras or lowlight cameras like NVGs – work
by detecting reflected light energy. But the amount of reflected light they pick up is not the
only factor that determines whether or not visible-light cameras can see an object: image
contrast matters, too.
If the object you are looking for has lots of contrast compared to its surroundings, you’ll
have a better chance of seeing it with a visible-light camera. If it doesn’t, you won’t see it.
That’s how camouflage works; by decreasing the visible contrast between an object and its
surroundings, that object becomes harder to see, even if there is plenty of light. At night,
when the lack of visible light naturally decreases image contrast, visible-light cameras suffer
even more in their ability to see.
moment), and the experience of the operator. Given similar conditions, you’ll be able to see
a freighter much farther away than a person in the water, for example.
When deciding what kind of imager to purchase, cooled or uncooled, take into account
your operating area (congested harbors, rivers, or open ocean), the types of targets you
encounter most often (pleasure boats, or larger vessels), and your primary mission profiles
(patrol, interdiction, search and rescue). When taken together, all of these factors will
guide you toward the imaging system that is right for you.
Maritime thermal imagers are the best tools
around for finding people in the water – even
at night.
Mid-wave or long-wave?
If you were paying attention in high school physics, or to Star Trek re-runs, you’ll
know that there is a broad range of energy called the “electromagnetic (EM) spectrum.”
The EM spectrum is a range of energy of varying wavelengths, from gamma rays and
X-rays (which have really short wavelengths) at one end, to radio waves (which have really
long wavelengths) at the other end. These types of energy are differentiated by their
wavelengths, which are measured in microns – a micron is one millionth of a meter.
Thermal imagers don’t suffer from any of these drawbacks. First, they have nothing
to do with reflected light energy: they see the heat given off by everything under the sun.
Everything you see in normal daily life gives off heat energy (called a “heat signature”) day
and night, in good weather and bad, even ice.
What’s more the heat signatures of people, boats, marinas, docks, pilings and all the
other things seen by maritime thermal cameras generally have better contrast at night
than during the day. As long as there is the tiniest bit of temperature contrast between
an object and its background, you can see it. In fact, many of the objects you could be
looking for, like people and boats, generate their own contrast because they generate
their own heat. Thermal imagers can see them so well because thermal cameras don’t
just make pictures from heat, they make pictures from the minute differences in heat
between objects.
Infrared energy is actually a sizable chunk of radiation in the EM spectrum, and sub-sets
(also called “wavebands”) of this energy have distinct characteristics. The two that we are
concerned with are the mid-wave infrared (MWIR) waveband from 3-5 microns, and the
long-wave infrared (LWIR) waveband from 7-14 microns. Which waveband is right for your
application?
For the most part, that decision is made for you once you choose a cooled or uncooled
imager. Most cooled imagers are only sensitive to the MWIR waveband, and most uncooled
imagers are only sensitive to the LWIR waveband. There are exceptions to this pattern,
but this division covers the majority of the maritime thermal imaging products you will
encounter.
Night-vision devices have severe range limitations as a by-product of their reliance on
reflected light energy. On the other hand, thermal cameras create images from heat that
is always there, they produce their own contrast, and they work best when we need them
the most.
So, is LWIR better than MWIR, or vice versa? Practically speaking, one is not better
than the other. MWIR energy travels through humid air better than LWIR energy does,
but at the ranges we’re talking about most operators aren’t likely to notice a difference.
Airborne law enforcement and SAR operators need to take this into account when
searching for a person in the water from thousands of feet up, when their slant range-totarget is measured in miles, but not maritime operators looking at targets less than a
mile away.
Cooled or uncooled? Mid-wave or long-wave? What kind of imager is right for you?
Now that we’ve got you all enthusiastic about thermal imaging for the maritime law
enforcement mission, what product is best for your application? Take a brief look at the
products offered for maritime law enforcement, and you’ll find a wide variety of capabilities
ranging from simple “point-and-shoot” cameras to imaging systems that can point to radar
returns and automatically track targets. Which is right for you and your department? Let’s
walk through a few of the basic factors for you to consider.
Other capabilities
There is more to your thermal imaging system than whether it has a cooler, or what
waveband of energy it sees. Maritime thermal imaging systems can have automatic target
trackers, they can automatically point to radar returns, and they can have differing levels of
image optimization software to help draw out faint targets from a cluttered scene.
Cooled or Uncooled
This option didn’t even exist until just a few years ago. The traditional thermal imager
has a cryogenic cooler inside that cools the infrared detector (the thing that actually senses
thermal energy) down to cryogenic temperatures of about -196°C (that’s -321°F, or 77K).
Today, there are solid-state detectors called “microbolometers” that don’t require the
cooler; these are used in uncooled cameras.
They can have lasers that point objects of interest out to other officers, and they can
have lasers that help calculate the latitude and longitude of objects within the camera’s
field-of-view. All of these are capabilities you need to think about above and beyond the
basics of coolers and wavebands.
There are pluses and minuses to each type of system. Cooled imagers have greater
sensitivity to thermal energy and can therefore see fainter targets from farther away
than their uncooled counterparts can. This increased performance comes at a price,
however – literally.
Benefits to the Maritime Law Enforcement Operator
Thermal imaging cameras do things the human eye cannot. They see heat, and are
therefore not dependant on light and contrast to create an image, working as well or
better at night than they do during the day. And, they can often see their targets from
much farther away than a person can because the human relies on light and contrast to
see things just like visible-light cameras and NVGs. Simply put, for the police boat’s mission,
thermal imaging cameras are vital partners to the work done by the human eye, providing
benefi ts beyond what you may think.
Cooled imagers are generally much more expensive than uncooled cameras both in
purchase price and in long-term cost of ownership. Coolers need to be rebuilt or replaced,
periodically. Not only are cryogenic coolers precision instruments built to extremely tight
tolerances, but they wear out over time (the actual time varies with the make and model,
but it’s usually in the 8,000 – 10,000 hour timeframe). They also contain helium gas that
can leak or become contaminated, requiring servicing.
See In The Dark
Thermal imaging cameras see the heat signatures of people and vessels in total
darkness, and through smoke, haze and light fog. This capability gives boat drivers an
added margin of safety when responding to calls at night, allowing them to navigate
confidently while avoiding floating debris, outcroppings of land, docks, pilings and boats
riding at anchor.
Uncooled cameras do not use coolers (obviously), so they are less expensive to
manufacture and require less maintenance. But, they also can’t see as far as cooled
imagers can. How far any thermal imager can see depends on many factors, the most
important being the size of the target, the difference in temperature between the target
and its background, the atmospheric conditions at the time (more on this last one in a
2
3
Maritime thermal imagers help boat operators
see in total darkness. They clearly have better
range performance and provide more image
detail than systems based on night vision goggle
(top) and I2 (middle) technologies.
Maritime Public Safety
Maritime Public Safety
First Mate MS
It also allows them to see what is happening on land without the need of extra lighting,
supporting land-based officers while maintaining effective cordon and perimeter actions.
Maritime operators using a thermal imager can monitor personnel in and around a crime
scene or search area. This allows the maritime and shore-bound teams to work together
more effectively and safely, as the boat crews can communicate possible safety issues to
units in and around the search area.
First Mate
Thermal
Imaging
Specifications
MS-224
Improved Search and Rescue Operations
The utility of maritime thermal imagers in the search and rescue role cannot be
overstated. In a man overboard scenario, the head of a person floating in the water is often
the only part of him that is visible; still, this shows up on the video display as a white ball
against a black or dark gray background because their body heat makes them warmer than
the water. This is as true at night as it is during the day, making them a crucial asset with
true 24-hour response capability.
Detector
Type
MS-324
240 × 180 VOx 320 × 240 VOx
Microbolometer Microbolometer
FOV
HM-224
HM-224 Pro
HM-324 XP
240 × 180 VOx
Microbolometer
HM-307 XP
HM-307 XP+
24° × 18°
24° × 18°
7° × 5°
6.70” × 2.31” × 2.44”
(172 × 58.7 × 62 mm)
9.4” × 3.3” × 2.6”
(10.5” × 3.3” × 2.6” w/ Extender)
11” × 3.3” × 2.7”
12 oz (340 g)
1.45 lb (653 g) with batteries
2.2 lb (984 g) with batteries
System Specifications
Size
Weight
Managing a rescue at sea is a complex undertaking, made less so when using a thermal
imaging camera. The thermal imager allows on-scene commanders to keep accurate track
of victims and rescue personnel in the water alike. This improved situational awareness
increases the safety of all involved.
Warranty
MSRP
Safety
2 Year
$1,995
$2,995
$3,149
$4,199
$5,249
$5,999
$7,499
$8,499
Range Performance†
A thermal imaging camera can see things at night that pose a threat to a police boat’s
safety, and the safety of her crew. When operating close to shore, the thermal imager
gives the crew important awareness of their surroundings: how close the shoreline is, their
distance from pilings or docks, and there is any debris floating in the area.
MS-224
HM-224 PRO
Detect Man
24° Lens
(1.8 m × 0.5 m)
~1,050’
24° Lens
Detect Man
(1.8 m × 0.5 m) 12° Lens (2x Extender) ~1,815’
~1,050’
Detect
24° Lens
Small Vessel
(2.3 m × 2.3 m)
Conclusion
Thermal imaging cameras are vital pieces of equipment for maritime law enforcement.
They expand the capabilities of police boats and their crews, while permitting these
important missions to be accomplished more safely and efficiently than ever before.
~2,940’
Detect
24° Lens
Small Vessel
(2.3 m × 2.3 m) 12° Lens (2x Extender)
MS-324
Detect Man
24° Lens
(1.8 m × 0.5 m)
~1,500’
Detect
24° Lens
Small Vessel
(2.3 m × 2.3 m)
~4,200’
HM-324 XP & HM-324XP+
~1,500’
24° Lens
Detect Man
(1.8 m × 0.5 m) 12° Lens (2x Extender)
Detect
24° Lens
Small Vessel
(2.3 m × 2.3 m) 12° Lens (2x Extender)
~2,590’
~4,200’
~1.3 mi
HM-307 XP & HM-307 XP+
Detect Man
(1.8 m × 0.5 m) 7° Lens
Detect Small
7° Lens
Vessel
(2.3 m × 2.3 m)
4
HM-324 XP+
320 × 240 VOx Microbolometer
5
~4,800’
~2.4 mi
~2,940’
~4,940’
Maritime Public Safety
M-Series (Single Payload)
M-Series (Dual Payload)
Navigator II
Voyager
SeaFLIR
320 × 240
VOx
Two
320 × 240 VOx
Cooled InSb;
320 x 240
18° × 14°
36° × 27°
20° × 15°
(Wide);
5° × 3.75°
(Narrow)
21.7° x 16.4°
(Wide) to
1.2° x 0.9°
(Narrow)
Daylight/
Lowlight
N/A
Daylight/
Lowlight
Daylight/
Lowlight
7.3” × 4.0”
× 7.4”
15.18” ×
18.68”;
15.5” × 22”
Swept Volume
Cylinder
9.0” × 15.2”
45 lb
28 lb
Thermal Imaging
Specifications
M-324XP
M-625XP
M-324L
Detector Type
320 × 240 640 × 480 320 × 240
VOx
VOx
VOx
FOV
24° × 18°
Daylight Imaging
Specifications
25° × 20°
24° × 18°
M-625L
M-612L
M-618CS
640 × 480 VOx
25° × 20°
N/A
12° × 10°
Microlux
Fixed
System Specifications
Size
7” dia. × 11.2” ht
7” dia. ×
11.4” ht
~ 9 lb
11.6 lb
Weight
Warranty
3 Year
2 Year
Voyager II
$84,000
MSRP
$8,995
$14,695
$14,995
$20,995
$23,095
$39,995
Contact
Voyager III
your FLIR
$105,000
representative
(Adds video
object tracking,
firefighting
features.)
$4,999
Range Performance†
M-Series
Navigator II
Detect Man
M-324XP
(1.8 m × 0.5 m)
~2,700’
M-625XP
M-324L
M-625L
Detect Man
(1.8 m × 0.5 m)
~1,500’
~1,020’ (310 m)
Detect
Small Vessel
(2.3 m × 2.3 m)
~1,500’
~2,700’
~2,900’ (880 m)
~3,750’
M-618CS
~3,900’
M-612L
Detect
M-324XP
Small Vessel
(2.3 m × 2.3 m) M-625XP
~4,200’
~1.4 mi
~4,200’
M-324L
M-625L
~1.4 mi
M-618CS
~1.9 mi
M-612L
~2 mi
Voyager
Detect Man
(1.8 m × 0.5 m)
~1.4 mi
Detect
Small Vessel
(2.3 m × 2.3 m)
~4 mi
† = Actual object detection range performance
may vary depending on camera set-up,
environmental conditions, user experience,
and type of display use.
All specifications are subject to change without
notice. Visit www.flir.com for the most up-todate specifications.
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[email protected]
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USA
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[email protected]
6
©2008 FLIR Systems, Inc. Specifications are subject to change without notice, check our website: www.flir.com. 04162008 [Rev 08/12]