UP-CLOSE Thermal Imaging and Night Vision
Night vision devices convert invisible infrared light into visible light, then amplifies that light millions of times to identify the target. Both active and passive night vision devices are available. Photo courtesy of Night Vision Depot.
Mission-Specific Uses
There are strategic uses for each of these technologies. It is important to understand each one so you can choose the technology that best suits your application and mission needs. The general field consensus is that having basic, low-budget night vision capability is better than no capa- bility at all.
So, with thermal image devices, what is important and what is not? With thermal imagers, the most important cri- teria is resolution. The 640 x 480 resolution is typically the best rating for handheld units. A system with a resolution of 320 x 240 will suffice for most operations, though 240 x 180 may be acceptable depending on the scenario. It is important to note that with each increase in reso-
lution, the cost increase is roughly $1,000 per unit. No camera is right for every thermal imaging task, but if you can identify a camera that falls within the aforemen- tioned resolution ranges, you likely have a camera that will offer superior performance for the vast majority of field applications.
40 LAW and ORDER I January 2016
Picture Quality What should you look for in a thermal imager? Picture qual- ity. A poor quality visual image will hinder any optical device and most infrared devices have fewer pixels than a regular cam- era. It is important to pay close attention to detector resolution and try to find something in the range outlined above. Also, be mindful of the difference be- tween detector and display reso- lution. Some manufacturers will boast about a high-resolution display and conceal the low res- olution of the detector when that is what really matters. Ease of use is also important. Some cameras boast what appears to be simplified functionality by offering as few as two buttons. Fewer buttons means that even simple tasks may require many button clicks. Sometimes more is less. More sophisticated naviga- tion pads can make for more in- tuitive use with fewer clicks. Since this is a police device,
heavy-duty durability is always a requirement. The camera will be deployed in a variety of environments, so durability is crucial. Impact resistance is an absolute must and, gener- ally speaking, products with longer warranties boast better impact resistance. Always check with the manufacturer and research product reviews.
Power supply and runtime is also important. The last thing an operator needs is to be out in the field with a dead battery. In this situation, it’s essential to be able to switch to a spare battery quickly and easily. Make sure your camera is outfitted with at least two batteries that can be quickly and easily switched out in the field.
Finally, photography. Why carry another piece of equip- ment to take photos? Many thermal cameras nowadays include a built-in 3- to 5-megapixel digital camera that si- multaneously captures visible light and thermal images. Digital photos that correspond to your thermal images may provide increased documentation during deployment.
Night Vision Priorities
What is important in a night vision device and what is not? Actually, judging the quality of night vision devices is sig- nificantly more complicated than with thermal imaging de- vices. The quality of any of these tools is determined by its optical characteristics and image intensifier tube. Night vision devices come in several ‘generations.’ First- generation units can be used in full or mostly full moon-
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