Quote from: chupacabras acheronsis on Mar 21, 2012, 07:26:05 PM
infra red and thermal are the same thing aren't they
Almost.
Infrared is the spectrum of light right next to the visible spectrum. All things that are not as cold as Absolute 0 give off some degree of heat, and that heat is infrared light. Infrared light is heat. Even the cold vacuum of space has some heat, even if that is just slightly above absolute 0.
Infrared is a much bigger spectrum of light than the visible spectrum of light so it likely has colors that we cannot even comprehend, since our eyes cannot see them.
When you see infrared photography online, the camera CAN see the infrared light, but it converts the image to "false colors" using our visible light spectrum so we can see it. We don't know what true infrared looks like.
Some examples of digital photos taken in the infrared spectrum and then assigned a visible light false color:
Because it does not require visible light you can take an infrared photo in complete darkness and the resulting photo will look like you took it in the middle of the afternoon!
Thermal imaging is when cameras use the infrared spectrum of light and then assigns a different visible light color to each temperature range. It too is a false color, but in this instance it is giving colors to different temperature ranges.
Basically if something has a temperature range of 100 degrees the camera might assign:
1-20 degrees = black
20-40 = blue
40-60 = red
60-80 = yellow
80-100 = white
Here are some examples of thermal imaging:
Popsicle melting:
http://coolcosmos.ipac.caltech.edu/image_galleries/images/popsicle_scale.jpgA cup with hot water inside:
http://coolcosmos.ipac.caltech.edu/image_galleries/images/hotcup_vis.jpghttp://coolcosmos.ipac.caltech.edu/image_galleries/images/hotcup_scale.jpgBoth are infrared, just varies in how the camera assigns visible light colors. Thermal is measuring the temperature, using infrared light.
We do not know what the real colors of infrared are, since our eyes and brains are not wired to see those colors. The wavelengths of infrared radiation is too long. That is why we use false colors.
I hope this helps.
