# Q & A: Finding information on thermography-Schlieren cameras

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Most recent answer: 10/22/2007
Q:
What is a thermography- schlieran camera? What does it do? How does it work? significance? (Please answer my question as soon as possible cause I have a assignment is due on next Tuesday)
- Vivian (age 14)
scarborough, On, Ca
A:

Vivian -

Much though I'm sure you'd like me to, I'm not going to write your report for you. I would suggest that you go to an online search engine (like https://www.google.com) and run a search. To give you an idea (and someplace to start), I ran a search for "schlieren camera" (the correct spelling is with an 'e', not an 'a'). I got a number of useful results including which (among other helpful things) describes how they work: https://www.google.com/search?q=schlieren+camera.

"Here's the simple principle of how this works...all you need to know is how a camera works. A lens produces an image of the striped reflective wall, or source grid, on a photographic film. This film is developed, and the eight-by-ten-inch negative is placed in front of the lens so that the dark lines of the negative, or cut-off grid, match up with the light lines of the source grid. So no light gets through ... Now, the source grid is quite large and the lens is quite small. Any disturbance causes light rays to bend and lets the light through. So if you put a person in the middle, that person gets imaged. You don't see the image on the negative, you see it behind the negative. What you're seeing is what gets past the negative - if the grids were completely aligned, you'd get a uniform gray. A TV camera focused on a ground-glass screen captures the light that sneaks past the cut-off grid and images the cause of the disturbance: the person's heat plume. "

How to do research like this is one of the most useful things that you can learn in school. Good luck!

-Tamara

(published on 10/22/2007)