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How Night-vision Cameras Work

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Author's Note: How Night-vision Cameras Work

Growing up, I was captivated by various kinds of vision, from the world-tinting wonder of cheap transparent plastic to the insectlike, compound-eye effect of kaleidoscopes. I wandered rooms of funhouse mirrors, clicked through View-Masters and collected and constructed optical gadgets small and large, from cheap microscopes and telescopes to pocket-sized periscopes.

My foray into night vision began with an ill-advised high school trek into an unfamiliar part of town to find a security retailer. My friend and I were full of beans and on a mission: he, to check out the "spy" gear, and me to look through a night-vision scope. Had we given the matter any thought, we would have assumed that the sales staff would take one look at our teenaged faces and give us the boot. To my surprise, though, one of the staff took me to a darkened demo room and let me peer through one of the shop's several-thousand-dollar scopes.

Once I'd gotten over the fear of breaking the thing, I was swept up in the marvel of seeing my own hand in pitch-blackness. I still recall it vividly: The lack of parallax and the odd, invisible-flashlight greenness of it combined to make me feel oddly disembodied.

I first encountered daytime UV and IR photography while writing another HowStuffWorks article, How to Capture Winter Scenes in Photography. As I surfed around the Web looking for experts on the subject, I came across landscapes that looked to be covered in frost and rime, but were actually the product of IR reflecting brilliantly off chlorophyll-packed leaves and grass. Ever since then, I have been obsessed with the idea of experimenting with IR and UV photography.

I think the desire to see the world differently -- both literally and metaphorically -- is a natural tendency, and a useful one, for artists, scientists ... anyone, really. Now, if you'll excuse me, I need to find a pawnshop that sells digital cameras on the cheap; I have some IR blockers to hack.

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