Infrared Waves& NIGHT VISION GOGGLES

The Electromagnetic SpectrumThe purpose of the electromagnetic spectrum is to explain (all) the different wavelengths of light. This spectrum is used by scientists to define colors that are invisible to us.

As you can see in the picture only the visible lights are visible to us and the visible lights are only a very small part of this Electromagnetic Spectrum.Fact: Most lights in the universe are actually invisible to us

Lights which are not visible to us

Lights visible to us

William Herschel

• Born 1738 in Hannover, Germany and died in 1822

• Well known as an astronomer and as a musician

• In 1757 he moved to england with his sister

• In 1781 he discovered a new planet, Uranus

• 1800, He conducted an experiment to find out how much heat passes through the visible colors of the spectrum

• He saw that the temperature was the highest just beyond the red area of the spectrum, he had discovered infrared.

The ExperimentGoal: To find the difference in temperature between the colors of the visible spectrum.

Materials:• A Glass Prism• Three Alcohol Thermometers• Black Paint or Permanent black marker• Scissors• Cardboard box• One blank sheet of white paper• Prism stand

Method:1. Blacken the thermometer bulbs2. Once the paint/marker has dried, tape the thermometers

together3. Place the sheet at the bottom of the cardboard box4. Place the glass prism at the top of the box (facing the sun)5. Rotate the prism until the largest spectrum you can get appears

on shaded part of the sheet6. Place the thermometers in the shade and record the ambiant air

temperature7. Then place each of the thermometers (bulbs) in a different

region of the spectrum : one in the blue, one in the yellow and one just beyond the visible red area.

This experiment should be conducted outside, preferably on a sunny day for the results to be as accurate as possible

Conclusion: It is by conducting this experiment thatHerschel was able to not only discover how much heat passesThrough the visible colors of the spectrum but he was also able To discover a color just beyond the red area of the spectrum. What we to this day call infrared.

Herschel’s Experiment

Herschel’s (reproduced) Experiment Diagram

Infrared Waves Characteristic• Wavelengths between 1 and 700 nm

• Frequency between 430 THz and 300 GHz

• Longer Wavelength than the visible lights on the spectrum

• Discovered in 1800 by William Herschel

• Travels at the speed of 300,000,000 m/s in a vacuum

This image shows why higher frequency means shorter wavelength and vice versa

Night Vision Goggles

Night Vision Goggles and Infrared

• There are 2 things you can use to obtain night vision

• Thermal imaging

• Image enhancement

Image enhancement: This works by collecting small amounts of light (from the lower part of the infra-red section on the spectrum) and amplifying these lights so that we can see them.

Thermal imaging: This works by obtaining heat from an object or a person and transforming that into an image. This is done using special lenses that focus the infrared radiation. Then, infrared detectors are used to scan this radiation.

Uses for Night Vision Technology• War

• Night hunting

• Security

• Observing nightlife

• Entertainment

Night vision technology was originally used to locate enemy targets during the night (war). Today this technology is still very much being used by the army for the same purpose and for navigation during the night. This technology is also used by the police for surveillance

DevelopmentGeneration 0:

• The very first night vision goggles were used by the German army in 1939

• The development of this device had started in 1935

Generation 1:

• The generation 1 night vision goggles were used during the Vietnam war

Generation 2:

• Generation 2 night vision goggles were much more effective than the ones that came before, the image given in complete darkness was much better/brighter.

Generation 3:

• The generation 3 night vision goggles again came out being much better than the generation 2 with a light amplification between 30,000-50,000x where the generation 2 only had a light amplification of 20,000x

GlossaryInfrared – Infrared is invisible to the human eye and has a wavelength which is slightly longer than that of red (normal red)

Radiations – The release of energy as electromagnetic waves

Wavelength – The distance between the top of two waves

Frequency – The rate at which an action occurs within a time limit

Citations