Drone eye capability and cost: there are basically three categories of electro-optical payloads made available for drones: fixed, small gimballed (down to about six inches in diameter) and large gimballed (six to nine inches). The types used very much depend on the type of data one expects from them, and this in turn dictates the choice of platform.

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The above sounds like stating the obvious. As will the fact of saying that much is owed to the miniaturisation of electronics. However, while no crystal ball has yet been invented to predict what lies in any future, a quick look over our shoulders will help realise that developments in the field of electro-optics have had a somewhat exponential growth.

Since the players on the defence market--producers and buyers alike--have traditionally (and not always justifiably) kept cost and price considerations close to their chests, a quick reminder of what actually happened on the civilian market might give us an idea of what to expect in the near future.

Miniaturisation Limits

Over the past ten years, the electronic camera market has exploded, to the extent that it is now almost impossible to find anyone able to develop your own old-fashioned film at a shopping mall. The amazing and perhaps surprising aspect here is that while 'miniaturisation' used to mean 'expensive' (remember the Minox spy camera of the 1950s), the word now means cheap. Indeed, the smaller the device, the fewer materials required and, of course, the lesser the weight and the packaging and despatching costs. Ironically, cameras could be made even smaller, but the limiting factor is ergonomics, since their users still need to operate its buttons, but fingers have not gone smaller. As a matter of fact, only five years ago, compact cameras were smaller than today's because their back displays (which are used as viewfinders) were still very small. Larger displays have now become more affordable and while cameras have become thinner, they have also grown taller.

On the cost front, a 1991 Nikon reflex camera fitted with a massive Kodak DCS100 digital back and underslung electronics pack would not only set you back 18,000, but would offer you an extravagant definition of 1.3 megapixels (Mpix). At the time, electronic compact cameras were not even a dream. Some ten years later, the size had dropped back to that of a 'normal' reflex, the price halved and the resolution grown to five Mpix. A mere five years later, in 2007, 600 [euro] would buy you a Canon 400D with over ten Mpix. On the compact camera front a 148-gram Olympus Mju 1200, for example, will cost around 300 [euro], but offers a resolution of twelve Mpix and a 6.8-cm diagonal display (now the norm) for you to admire your shots on. Icing on the cake, depending on memory size fitted, one can use it as a basic cinematic camera.

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Software

Here too--and especially in this particular sector in fact--descriptions of defence image-processing software capabilities are kept very secret. But again, a comparison with the software packages used in commercial cameras only over the past five years provides a useful yardstick. The fact that electronic cameras use software to 'translate' what the sensor catches into a viable image is not often perceived by the man in the street. Anyhow, the package is pretty much what the chemistry did in old film cameras, and now colour rendition, contrast and speed much depend on its capabilities. A few years ago, one had to wait quite a while between five-Mpix shots. Nowadays three to six shots per second is the norm. There is every reason to believe that the military sector has followed a similar path.

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Of course, while the military also use CCD cameras, they also--and primarily-use infrared sensors, but the progress process in terms of sensor size, capability and cost (on a different scale, of course) is pretty analogous if one can use this word in the context of digital devices.

Recent Introductions

At the lower scale in terms of size, Flir had the thermal imaging Photon 320, which has already been reviewed in the past by Armada. The company is now introducing the latest variant, the Photon 640, which with a 640 x 480 microbolometer sensor, offers four times the number of pixels of its predecessor as well as x 2 and x 4 digital zoom factors. Not often mentioned is the fact that capabilities depend on the destination of the items. In the case of the Photon 640, for example, the nominal operating frame rate is 30 Hz, but for the export market Flir has a slow-rate package that circumvents export restrictions.

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Aim Infrarot in Germany is perhaps less well known but has been a supplier of lightweight infrared cameras that have distinguished themselves in Kosovo and Afghanistan, particularly onboard the EMT Luna series of drones. The company currently markets the [micro]Cam UC uncooled infrared camera which weighs 180 grams. This offers a field-of-view of 41[degrees] x 31[degrees] with a detection and identification range of 800 and 130 metres respectively. The [euro]Cam HP on the other hand is heavier at 1.4 kg, but is of the cooled variety, offering identification at a range of 500 metres.

In terms of turret systems, Cloud Cap (also known for its autopilots, particularly the Piccolo series) has developed a lightweight gimballed turret that is able to accommodate a variety of sensors. Known as the Tase, it features an 'environmentally sealed' payload bay, allows for pilot, stabilised or latitude/longitude/ altitude flight modes. Its parallel drive and composite material design help reduce rotating mass (and thus inertia), but offer a slew rate of 200[degrees] per second. The Tase weighs 900 grams and a typical infrared sensor would be the Flir Photon discussed above.

Interestingly, Cloud Cap also offers the Tase Duo, which can accommodate two sensors; namely a Sony day camera and an infrared Flir Photon sensor. Of similar construction as the Tase and using a base of identical size, the Duo sees its sphere diameter expanding to only 12.7 cm and its weight just exceeding the kilo mark at 1060 grams.

Larger and heavier, but good for flight speeds of up to 250 knots, the new four-gimbal Emos from Elbit carries an 8-12[micro]m, 320 x 240 microbolometer infrared sensor and a colour CCD camera. As for the Tase, the Emos is self-contained and its base houses the entire related electronic package, including the autotracker.

Moving upscale, the Micro Compass, introduced by Elbit during the fourth quarter of 2007, exemplifies the sizes that current multiple-sensor (i.e. more than two) turrets command.

Particularly aimed at drones of the size of the Skylark II, in other words with a take-off weight of 35 kg and an endurance of six hours, the Micro Compass adds an infrared pointer to a cooled infrared sensor and colour television camera. This takes the systems in the eight-inch (20 cm) category of turrets and into a weight bracket of eight kilos. Incidentally, the electrically powered Skylark II configured with the Micro Compass has recently been selected by the Korean armed forces.

Records are meant to be beaten, but for the time being Flir's Mep packs a wide field-of-view 640 x 480 uncooled microbolometer, a 640 x 480 narrow field-of-view cryo-cooled infrared camera, a colour CCD camera, a 1.54-mm eye-safe, four-km rangefinder and a 1.06 mm, two-km-range laser designator into a single 7.25-inch (18.5 cm) stabilised turret.

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