• Question: How do infrared cameras help scientists?

    Asked by anon-258031 on 26 Jun 2020.
    • Photo: John Hadden

      John Hadden answered on 26 Jun 2020: last edited 26 Jun 2020 1:31 pm

      Infrared cameras allow us to see light which our eyes can’t see. You can classify light (or more generally electromagnetic radiation) by the length of the electromagnetic wave associated with it.

      The infrared range spans a large wavelength range from around 700 nanometers which is just redder than we can see(that is 700 billionths of a meter – or around 1 hundreth of the width of a human hair around 70 micrometers) … all the way up to 1 mm. Above this the radiation is called microwaves (like what is used in a microwave oven).

      Radiation in the infrared contains lots of useful information. For example near-infra red cameras can be used to see in the ‘dark’ – when there is no visible light, but there is a low level of infra red light.

      Thermal long wavelength infra red cameras can also be used to image ‘heat’ from the ‘black body’ radiation which all objects emit. The hotter an object is, the shorter the wavelength of this radiation, as well as its brightness. For temperatures from around 89 Celsius down to minus 80 Celcius to, the radiation is around 8–15 micometers (so 8-15 millionths of a meter or around a quarter of the size of a human hair).

      Much hotter objects are much brighter, and emit shorter wavelengths, so for instance an old incandescent (not a fluorescencent) light bulb has an element which heats up to several thousand Celsius, which emits some visible light – however most is still in the infra red specturm.

    • Photo: Yueng Lenn

      Yueng Lenn answered on 26 Jun 2020:

      And guess what, there are super power infrared sensors on many scientific satellites at the moment. These sensors look at the planets surface and record brightness at different near infrared wavelengths. These data help us work out what the temperature of the sea surface, land and atmosphere are. How cool is that?

    • Photo: Mike Taverne

      Mike Taverne answered on 13 Jul 2020: last edited 14 Jul 2020 12:41 pm

      Well, others have already given proper answers.

      I will answer in a way very specific to one of my experiments:

      I measure how much light gets reflected at different angles from my samples (photonic crystals).
      The light I am interested in is infrared (near-infrared to be exact: 0.9-1.7um, i.e. just slightly longer than visible wavelengths).

      The way the experimental setup works is that you first use a camera to position the sample right under your light beam. Then you flip a mirror, so the light goes to a spectrometer (1) instead of to the camera.

      Unfortunately, we use a camera for visible light and a visible light source that only emits a tiny amount of infrared.

      This allows us to see the sample so we can position it. But the weak infrared light means we need to measure for a long time to get enough data.

      If we had an infrared light source and an infrared camera, we could still see the sample to position it and spend less time measuring each sample! 🙂

      So an infrared camera (and the light source to go with it) would save me a lot of time!

      (1) A device telling you how much light of each wavelength/frequency (think color, except extended to invisible light) there is.

Comments