This "color" infrared image was obtained using the
2MASS
three-band
survey camera. The camera produces simultaneous images
in the J (1.2 micron wavelength), H (1.6 micron), and Ks (2.2 micron)
photometric bands. These three images were combined by assigning
blue to the 1.2 micron image, green to the 1.6 micron image, and
red to the 2.2 micron image (i.e. longer wavelengths equal redder
colors, just as is the case for visible light). Since I am
warm, my skin glows brightly at 2.2 microns -- thus my red
skin color. I have a cold nose and cold fingers, however.
Human skin is quite non-reflective at these wavelengths, so my
cool skin appears nearly black in this image.
The color image is composed of the three images below. In order, they are J (1.2 microns), H (1.6 microns), and Ks (2.2 microns).
Click here for a larger jpeg format image of the color image above.
This image was obtained using
the NICMASS infrared camera.
A single small lens relayed the image through an infrared filter that
permits only light with a wavelength of 2.2 microns (2200 nanometers,
or 22,000 Angstroms) to reach the infrared detector array. This
"color" of light is invisible to the human eye. This wavelength is
approximately 4 times greater than the wavelengths of light that the
eye typically detects. Most everything humans see with their eyes is
seen via reflected light with the exception of self-luminous sources
of light like the Sun and incandescent light bulbs.
The Sun and light bulb filaments glow because they are hot. The
glow produced by hot objects is called "blackbody radiation." The
brightness and color of hot glowing objects is dictated by their
temperature. The Sun has a temperature of 6000 degrees and glows
"white-hot", emitting most of its light at a wavelength of 0.5 micron
(the green part of the spectrum). Cooler objects emit most of their
radiation at longer wavelengths. At room temperature all objects glow
predominantly at infrared wavelengths. The picture you see above
was obtained in a darkened room and shows that I am glowing at
infrared
wavelengths. The hotter any point in the picture is, the brighter the
glow.