Axis Q1910 Thermal Network Camera review

Stop messing

It is time for all cameras, both fixed and hand-held, to have user-controlled frequency selection as a continuous variable throughout its entire range.

By specious on 6 Apr 2010

cool

read more http://www.e-castig.com/index.php?r=K1kwg

By niceguy on 6 Apr 2010

Glass and Infra-Red Radiation

You comment that "the camera won't work well through glass". This is no surprise, since you also say that the camera works in the far infra-red (around 10 microns) and glass does not transmit well above about 1.2 microns (it reflects longer wavelengths - the original greenhouse effect!). It will, however, see through black plastic bin-bags and, perhaps, thin clothing.
Special materials, such as Germanium or Zinc Selenide, have to be used to make lenses for these cameras.
I would not expect it to see well through fog or heavy rain and the black smoke from burning tyres, although wood smoke (for example) would appear transparent to it.

By dwrobinson on 7 Apr 2010

Clarity

Can Specious provide more info? Regarding the camera’s inability to work through glass, I’ve mentioned in the review that Axis offers an external casing for outdoor use that has a germanium window. Not sure why you’d want to look through bin bags, though.

By DaveMitchell on 7 Apr 2010

Thermal vs Optical

Ordinary things often look very different through a thermal imager. for example, both a white horse and a black horse (to the human eye) would look the same through a thermal imager, because each horse's body is much hotter than the surroundings, but the body of the white horse is the same temperature as the black one - and temperature is one of the important parameters (although emissivity is also a factor). Objects that might be invisible to the eye, because of an obscurant barrier (such as smoke or black plastic) or camouflage (such as green painted screens) become clearly visible in thermal either because the thermal radiation penetrates the barrier or because foliage reflects infra-red radiation whereas green paint often absorbs it (so an object that is painted green looks different from green vegetation in a thermal image). Look at the (glass) spectacles that are shown in the image in the article - you cannot see the man's eyes, just a reflection of the surroundings. Thermal cameras require special materials for lenses and windows (e.g. to look out of an armoured vehicle, through a small window in the armour); often these 'windows' are made from Germanium, as this is transparent to 10 micron thermal radiation, even though human eyes see it as black and opaque.
One hidden danger is that those Germanium lenses, prisms and windows often have radio-active materials (such as Thorium) added to them to enhance their optical or mechanical properties. This makes them potentially dangerous when damaged.
Ordinary window glass blocks radiation longer than about 1.2 microns; even fused quartz gives up around 4 microns. To detect efficiently the thermal radiation from people (around 300 Kelvin) the thermal detector needs to respond to far infra-red radiation around ten microns (because that is what objects at that temperature emit most strongly - basic quantum physics!). Germanium and Zinc Selenide are, pretty much, the only useful materials for transmitting far-IR.
Bin bags are quoted only as an example of how different things look when seen by the human eye and by the thermal camera. Watch some of the ubiquitous TV programmes that show how the police use thermal cameras to find the bad guys when they are hiding in the bushes on a dark night, to see what I mean.

By dwrobinson on 7 Apr 2010

Not radioactive

I passed the comments from dwrobinson on to Axis and it has confirmed that the germanium lenses used in its thermal cameras do not contain radioactive material

By DaveMitchell on 29 Apr 2010