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A mirror is under normal circumstance used to reflect Electromagnetic radiation also known as photons (light) and in airport security or medical facilities, they use X-rays to detect anomalies inside objects or bodies to detect narcotics or injuries. However, I always wonder what if I add a mirror inside the luggage or put a mirror in front of me during scanning?

That in mind, how would an X-ray scanner see the mirror? Would it be invisible? I am sure I am not the first one to think of this, as a lot of security and criminals thought of this, however I never got an answer, so can someone tell me please?

If there are X-ray reflecting mirrors? Why don't Airport security ban these items and Mirrors all together? Would X-Ray mirror look like a normal mirror? Do they reflect visible light spectrum as well?

dmckee --- ex-moderator kitten
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3 Answers3

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The thing that makes a mirror a mirror is a that it has a high reflectivity (and is very smooth of course, but that doesn't enter into this issue), but all optical properties including reflectivity are functions of wavelength.

The mirror is not reflective in the x-ray band, so it looks like a layer of glass (moderately dense) and a very thin layer of heavy metal (rather denser). It can be seen in the image but is in no way remarkable.

It will look just like any other thin layer of moderately dense material.

dmckee --- ex-moderator kitten
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dmckee points out that an ordinary mirror doesn't reflect X-rays, but if you could find an X-ray mirror and put it in your case it would just appear black.

When you look at yourself in the mirror you're seeing light from your skin/clothes that hits the mirror and is reflected back towards your eyes. But airport X-ray machines work by passing X-rays through the luggage. The X-rays are emitted on one side and detected on the other. An X-ray mirror would reflect the transmitted X-rays and stop them passing through your case, so the X-ray detector would just see it as a black sheet.

John Rennie
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As others have noted, an ordinary mirror will not reflect x-rays. X-ray mirrors do exist, but will also probably not do what you want here. It's very difficult to manipulate the optical trajectory of an x-ray. The critical angle of typical metal foils at x-ray wavelengths is a few degrees at most -- that means that the x-ray is only reflected if it hits the mirror surface at a very, very shallow angle, and its direction only changes by a few degrees. If the x-ray hits the mirror head-on, as it would if you were holding the mirror up in front of yourself while going through the scanner, the x-ray would just pass through the mirror rather than being reflected.

Adrian
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