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Are there cameras which can see through opaque objects (i.e. a reasonably dense curtain, cardboards or walls)?

And by see I mean in almost full color the way a regular camera would work.

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2 Answers 2

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"full color the way a regular camera would work."

By definition, no. Cameras (or rather, imaging devices) that see through things work by using wavelengths which go through other materials but human eyes cannot detect, and translating those images into those wavelengths on a monitor which we can see. A false colour spectrum, if you will.

But colour, by definition, are the visible wavelengths we can see so there's a contradiction there.

That said, the only images I have seen that actually map invisible wavelengths to visible wavelengths are space telescope photos. There, effort is made to produce detectors that can distinguish wavelengths from one another. In images like these, the colour in the image is representative of the non-visible wavelength and the brightness of the colour is representative of the intensity of that wavelength.

But The vast majority of devices seems to just use broadband sensors that can measure intensity but not distinguish wavelengths, thereby producing what is essentially a monochromatic image; Equivalent to a black & white or greyscale image in the visible spectrum. Usually such images are just mapped to a grey scale for a black and white photo such as X-rays and night vision. On occasion, the intensity is mapped to a scale containing visible colours which is what you see in the typical thermal image. But both are still essentially monochromatic images, unlike the space telescope photos.

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  • $\begingroup$ Thanks for the response. Is it possible to map results from these spectrums into some colorspace so that we can essentially "see" it as if it was video taken by a regular camera? $\endgroup$ Oct 30, 2021 at 6:30
  • $\begingroup$ @AlbertKinterman of course. Take any x rays slide and colour them. Or all kinds of images in medical applications. Etc. $\endgroup$
    – Alchimista
    Oct 30, 2021 at 7:24
  • $\begingroup$ @AlbertKinterman That's basically what my answer said: false colour spectrum. But I added more detail. See updates. $\endgroup$
    – DKNguyen
    Oct 30, 2021 at 19:09
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    $\begingroup$ Re, "the only images I have seen that actually map invisible wavelengths to visible wavelengths are space telescope photos." Try Googling for "back scatter X-Ray," $\endgroup$ Oct 30, 2021 at 19:48
  • $\begingroup$ @SolomonSlow Oh the thing used at airports. $\endgroup$
    – DKNguyen
    Oct 30, 2021 at 23:06
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In the beginning of 2015, USA Today launched a wave of publications on a handheld radar called RANGE-R that has been used by the U.S. police and other government services. The radar system is able to ‘see through the walls’. To be more accurate, it registers motion inside closed spaces. The radar system’s high sensitivity is able to detect a hiding man’s breathing somewhere deep inside a building, behind several walls. The technology was only available for some governmental services. Today, the radar system is more widely used due to technological advancements that contributed to price decreases.

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  • $\begingroup$ I've read about this, though from what I understand it's still not able to see in color, an functions more like a highly sensitive motion detector? $\endgroup$ Oct 30, 2021 at 6:34
  • $\begingroup$ +1 Range-R has a Wikipedia article about it. en.wikipedia.org/wiki/Range-R and it says about the same as what you said. $\endgroup$ Jul 30, 2022 at 12:56

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