how does the laser thermometer measure how hot/cold something is, by just shining on it with a few rays of laserlight?

204 views

how does the laser thermometer measure how hot/cold something is, by just shining on it with a few rays of laserlight?

In: Technology

It has nothing to do with the laser, that is just an indicator to see where it is pointed. Instead the temperature is measured by gauging the frequency of infrared light the object emits, as that directly relates to the temperature of the object. If it gets hot enough the frequency actually raises into the visible spectrum which is why very hot things will start to glow.

Heat and light are just two forms av energy, and by measuring the speed and wavelength of the returning light you get the temperature.

“””
The light bounces back at different wavelengths depending on the temperature of the air and the object that was hit. This is also the reason why the laser might reach a few meters but not being able to calculate the correct temperature over a distance further than a few centimetres.
“””

They have little lenses that focus the infrared light coming off of the surface of your skin into a detector (thermopile). The detector turns the light into heat, the heat into electricity, and then reads out the result.

The laser just helps you pointing it in the right direction. You get the same thermometers without lasars as well. What these thermometers does is to measure the infrared light coming from that area. You may have noticed that hot things tends to glow red, orange or even white depending on its temperature. It still emits light even if it is not red hot, just that it its color is an invisible infrared one. You may feel this as a warm glow from hot things. The sensor in an infrared thermometer is able to measure this infrared light and using this information it can calculate the tempearture.