Yup. Light is a radio wave. The issue<div>is whether one can form images, or </div><div>otherwise manipulate the radiation. e.g.,</div><div>1THz is about 0.03 cm, which is probably</div><div>in the microwave range, but it can be </div>
<div>imaged. And it can go through many</div><div>things. And since 0.03 cm is much </div><div>smaller than everyday objects, it could</div><div>spot a wiring error in a wall. Or people</div><div>doing all kinds of things in their houses.</div>
<div><br></div><div>But you won't get a unit from Cyberguys.</div><div>What you can "see" depends on technology,</div><div>which always changes, and what you can </div><div>spend.</div><div><br></div><div>//endjob -- IBM 360 JCL.</div>
<div><br></div><div> -- Bob</div><div><br></div><br><div class="gmail_quote">On Thu, Jan 28, 2010 at 9:31 PM, Michael Mol <span dir="ltr"><<a href="mailto:mikemol@gmail.com">mikemol@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Ah, in that case, I should have directed my response to Ben. 1THz is<br>
actually far, far, deeper than even the far-IR stuff I work with.<br>
1THz has a wavelength of a few hundred micrometers; My stuff doesn't<br>
even get as long as one micrometer.<br>
<br>
It borders on radio waves, which is how it gets its greater<br>
penetration capability.<br>
<br>
For a quick comparison:<br>
<br>
100s of nanometers -- visible spectrum, IR<br>
~300 micrometers -- This terahertz tech.<br>
~3cm -- 10GHz ISM band, not used for much, but in the general vicinity<br>
of satellite TV.<br>
~6cm -- 5GHz ISM band, commonly used in 802.11a and 802.11n.<br>
~12.5cm -- 2.4GHz ISM band, commonly used in bluetooth, 802.11b,<br>
802.11n, most cordless phones, newer R/C car and airplane controllers.<br>
~33cm -- 900MHz ISM band, mostly used for older cordless phones, R/C<br>
cars and airplane controllers.<br>
<br>
Below that, you'll find your over-the-air and cable TV channels.<br>
<br>
If you're really worried about see-through-walls EM intrusion, you<br>
could conceivably set up a Faraday cage designed to trap the bands<br>
you're worried about.<br>
<div><div></div><div class="h5"><br>
On Thu, Jan 28, 2010 at 9:13 PM, Bob Kline <<a href="mailto:bob.kline@gmail.com">bob.kline@gmail.com</a>> wrote:<br>
> Oh, I understand. The original question<br>
> was what Cyberguys level gadgets could<br>
> do in terms of seeing bad wiring inside a<br>
> wall.<br>
> If cost is no object, one can of course<br>
> do more. A lot more.<br>
> Devices operating in the 1THz range<br>
> can see people inside their house.<br>
> Through walls. There were discussions<br>
> about the legal implications of all this<br>
> several years ago.<br>
> -- Bob<br>
><br>
> On Thu, Jan 28, 2010 at 9:04 PM, Michael Mol <<a href="mailto:mikemol@gmail.com">mikemol@gmail.com</a>> wrote:<br>
>><br>
>> On 1/28/2010 8:48 PM, Bob Kline wrote:<br>
>> > How cool was the room?<br>
>><br>
>> Thermostat is normally 72F, but that's in another room. I'm in the room<br>
>> with the servers, which is usually about five higher.<br>
>><br>
>> ><br>
>> > You seen to have a short sleve<br>
>> > shirt on, but I think I can see the<br>
>> > back of a chair, walls in the the<br>
>> > background. Is it a big room?<br>
>><br>
>> I wear short-sleeves year-round, primarily because of the higher<br>
>> temperatures in the vicinity of my workstation. That was actually taken<br>
>> in Dec of 2007, I think. (The date is off on Flickr, but that's because<br>
>> the source is a BMP, and the timestamp was screwed up due to a few<br>
>> workstation migrations.)<br>
>><br>
>> Room is about 750 ft^2, or about 6000ft^3.<br>
>><br>
>> ><br>
>> > Jet gets to the fact that because<br>
>> > you stand out some the room might<br>
>> > be large, and-or cool<br>
>><br>
>> I don't think you understand how far-IR temperature monitoring works.<br>
>> If you'd like, I can delve into a discussion of microbolometers and<br>
>> measurement adjustments stemming from surface emissivity, ambient<br>
>> temperature and ambient humidity values.<br>
>><br>
>> There's more at work than just the wavelength of quanta, there's also<br>
>> intensity of emissions, considerations of atmospheric absorption and<br>
>> considerations of ambient temperatures reflecting off of other surfaces.<br>
>><br>
>> What it boils down to is that in practical conditions, I can (and do,<br>
>> for use cases such as those that that software was written for) measure<br>
>> surface temperatures to within 0.01C.<br>
>><br>
>> Don't forget I also control the palettization -- the conversion of raw<br>
>> temperature numbers to RGB pixels, which goes towards making differences<br>
>> "stand out."<br>
>><br>
>> ><br>
>> > -- Bob<br>
>> ><br>
>> ><br>
>> > On Thu, Jan 28, 2010 at 8:18 PM, Michael Mol <<a href="mailto:mikemol@gmail.com">mikemol@gmail.com</a><br>
>> > <mailto:<a href="mailto:mikemol@gmail.com">mikemol@gmail.com</a>>> wrote:<br>
>> ><br>
>> > On Thu, Jan 28, 2010 at 8:02 PM, Bob Kline <<a href="mailto:bob.kline@gmail.com">bob.kline@gmail.com</a><br>
>> > <mailto:<a href="mailto:bob.kline@gmail.com">bob.kline@gmail.com</a>>> wrote:<br>
>> > > On Thu, Jan 28, 2010 at 6:03 PM, Michael Mol <<a href="mailto:mikemol@gmail.com">mikemol@gmail.com</a><br>
>> > <mailto:<a href="mailto:mikemol@gmail.com">mikemol@gmail.com</a>>> wrote:<br>
>> > >><br>
>> > >><br>
>> > >> The chief problem with "darkvision" as it applies to passive<br>
>> > near-IR is<br>
>> > >> that there is a lot of ambient near-IR radiation that's not<br>
>> > related to<br>
>> > >> warm bodies.<br>
>> > >><br>
>> > >> In short, your warm body radiation in the near-IR will be there,<br>
>> > but<br>
>> > >> largely drowned out by the ambient near-IR radiation.**<br>
>> > ><br>
>> > > The peak wavelength for a human body<br>
>> > > thermal spectrum is 10 microns - in the so<br>
>> > > called long-wave infrared range. You shine<br>
>> > > if you're standing out in the snow, but the<br>
>> > > human body is not really very hot. About<br>
>> > > the same as your house interior, which is<br>
>> > > that temperature, by design. So you don't<br>
>> > > stand out much.<br>
>> > > See <a href="http://en.wikipedia.org/wiki/Infrared" target="_blank">http://en.wikipedia.org/wiki/Infrared</a><br>
>> > > -- Bob<br>
>> ><br>
>> ><br>
>> > <a href="http://www.flickr.com/photos/28208534@N07/3681419505/in/set-72157620862996406/" target="_blank">http://www.flickr.com/photos/28208534@N07/3681419505/in/set-72157620862996406/</a><br>
>> ><br>
>> > I don't?<br>
>> ><br>
>> > What kind of image is this? i.e., how<br>
>> > is it corrected?<br>
>> ><br>
>> ><br>
>> ><br>
>> > _______________________________________________<br>
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