Infrared Radiation Flashcards
What does blackbody do to all the radiation falling on it?
Absorbs all the radiation falling on it.
How do grey or white objects compare to black bodies?
Grey or white objects will emit less radiation.
What affects the total radiation emitted by a surface?
The colour, for example black Matt emits much more than shiny white
How are thermal images made?
The image is detected by several thousand detector elements arranged in a focal plane array which means in a grid.
What is the picture of an infrared image called?
Thermogram
What is a false colour in a thermogram?
The colour assigned to a temperature.
What can affect the surface temperature?
What is underneath the surface.
Why do you glasses appear black?
Because glass and optical plastics cannot transmit infrared.
What is meant by resolution?
It is a measure of how much detail we can see.
What are the two types of resolution and what can limit each type?
Spatial resolution. This is a measure of how well we can distinguish between objects at slightly different places.
Thermal resolution. This is a measure of how you can distinguish between objects at similar temperatures.
What are four examples of thermal detectors?
Thermocouples bolometers, pyroelectric detectors, and liquid crystals.
Describe two features of thermal detectors?
their response does not depend on the wavelength. They work well at room temperature.
What are photonic detectors made from?
They are made from semiconductors.
What is an advantage of photonic detectors over thermal energy?
They are more sensitive and respond faster.
What are two disadvantages of photonic detectors compared to thermal detectors?
They are more expensive and they require cryogenic cooling.
Give some examples of thermal imaging cameras and what they are used for.
Border security – border security specialist protect the country’s borders again smugglers and other intruders with thermal imaging camera they are able to see a man at a distance of 20 km away in total darkness.
Commercial security - as security customers benefit from thermal imaging cameras because they help them to secure the cities like Paul’s apples new killer facilities where has this estate and many more against intruders.
Building – building professionals look for installation losses and of the building related defects with the thermal imaging camera. Finding installation losses and reparing them results in huge energy savings.
Gas detection – gas leaks can also be detected seamlessly with a thermal imaging camera.
Law-enforcement – police officers use the power of thermal imaging to see without being seen they can easily find subjects in total darkness without giving away their position.
Automation – thermal imaging cameras are also installed to continuously monitor production processes and avoid fires.
Outdoor – outdoor enthusiasts can see clearly at night with the help of thermal imaging cameras.
Firefighting – firefighters are able to see through smoke. It helps them to find victims in a smoke-filled room and also to see if Fires are Well extinguish. It helps them to save lives.
What is thermal resolution?
Thermal resolution is a measure of how well the temperatures can differentiated (identified as being different from each other).
What is a black body?
A black body is a theoretical object which absorbs all the electromagnetic radiation that falls on it and reflects none.
Objects which are good absorbers of radiation are also good emitters, so a perfect black body would also be a completely efficient emitter of thermal radiation.
Physicist use the concept of the blackbody to develop a theory explaining thermal intensity graphs – thermal radiation is sometimes called blackbody radiation.
What is thermal radiation?
All solids liquids and then scuffs above zero Kelvin (absolute zero) give us some electromagnetic radiation.
The intensity and frequency of the radiation will depend on the temperature of the object and how good the object is at emitting the radiation.
This radiation is known as hot body radiation, or thermal radiation, even though the object emitting it may not be at a temperature we would describe as hot.
