Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Measuring InfraRed
Name:  Harry W.
Status:  other
Age:  40s
Location: N/A
Country: N/A
Date: 2000-2001


Question:
How is it possible to measure the wavelength of light emitted from an Infra Red heating element?


Replies:
The wavelength(s) of infrared radiation is measured with an instrument called an infrared spectrometer [or spectrophotometer]. It consists of a slit of variable width which forms an slit-image of the impinging infrared radiation. The infrared image is then focused by mirrors on to a grating [in older instruments this element could be a large crystal of NaCl] designed to diffract infrared radiation, that is spatially separate the radiation according to wavelength in much the same way a prism spatially separates the various wavelengths of visible light. The diffracted infrared radiation then passes through a second slit that shields the detector from all the diffracted radiation except a narrow bandwidth. This narrow bandwidth of radiation falls on an infrared detector. The infrared detector can be any number of devices that convert the radiation impinging upon it to an electrical signal that is amplified and displayed on some sort of chart. The detector can be a thermocouple, or any number of solid state devices.

I hope that is not more about "elephants" than you cared to know!

Vince Calder


Radios are sensors constructed to detect specific wavelengths much longer than infrared light. Televisions respond to specific wavelengths between radio and infrared. Digital cameras respond to wavelengths in the visible range. Just adjust the sensors so they notice slightly longer wavelengths and you have a camera with sensors that respond to infrared. By having the frequency/wavelength adjustment like a radio tuner, you can determine the wavelength by "tuning in" to the signal from the heating element.

Kenneth Mellendorf



Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory