Variable spectrum common visors/cameras I guess almost everyone knows about the really small area of electromagnetic spectrum that humans are able to see.
Well, it is just not fair :-).
Why there is still no multi spectral (means with variable spectrum) visors available on the market ?
The idea is to get an predefined by device settings spectrum area (can be changed at any time by user) and map it to common RGB palette in order to visualize all the spectrum.
Are there any unsolved technological problems or restrictions with that ?
What areas of spectrum are still difficult/unavailable to observe ? 
As far as I understand this kind of device is quite simple and is just a simple modification of common cell phone camera (so it is cheap for mass production).
No doubt, this kind of device will reveal a lot of great hidden info on EM interactions from the world that will be easy to observe in dynamics and will be quite useful for lots of people in all areas from science to applications. I guess it will be a revolution in technics/biology related areas or natural sciences (and also a good device to common use).  
 A: First of all, you probably know about night vision googles, which slightly increases the spectrum available to human eyes. But why not expand this type of technology to a wider band, of frequencies? I would say there are two reasons


*

*Most technologies designed to detect electromagnetic radiation are only efficient within some relatively narrow band of the spectrum. Even the human eye uses three different detectors (cones) to detect different colours. Your cell phone is another good example: The technology used to detect and emit radiowaves (the antenna) is very different from the technology used to detect and emit visible light (camera chip / pixels). A visor or camera such as you suggest would have to be able to shift between a wealth of different detectors (some of which might be quite unwieldy) as you scroll through the spectrum.

*It may very well not lead to anything revolutionary. One field which has immense interest in detecting a wide range of EM radiation is astronomy, and they basically already can using a combination of satellites and telescopes. Using these technologies is more practical than glasses, and jamming them all into one device would be unnecessarily complicated. For most of the interesting EM emission on earth, a pair of night vision goggles and a radio would probably suffice.


It would be very cool to have, but I am afraid that the price for a practical device of this kind would be much too expensive to build just because it's cool.
