Digital infrared thermometer has entered ordinary households

Posted by aijj on January 6th, 2020

Thermometers are not new to us, especially common thermometers, which have become one of the essential items at home. It is difficult to imagine how humans measured temperature before the thermometer was invented. Digital infrared thermometer solve the problem of general thermometers that require a shake.

Measuring principle of thermometer

Almost all liquid thermometers are made using the principle of thermal expansion and contraction. However, the degree of expansion varies with different substances, and this substance constant is often referred to as the coefficient of expansion. Volume expansion is evident in liquids such as water, alcohol, and mercury. Among them, the expansion coefficient of mercury is higher than that of water and lower than that of alcohol. Compared with water, the volume of mercury changes more significantly with temperature, and the rate of mercury rise and fall is slower than that of alcohol.

Therefore, we take out the thermometer from the high temperature, and its reading will not be disturbed and cause errors. The common medical thermometer's working substance is mercury. Why do we often see doctors and nurses throwing the thermometer before using it?

This is because the design of the lower port of the thermometer is small, and there is a very narrow neck above the glass bulb containing mercury. When measuring body temperature, mercury expansion can rise into the above glass bubble through the constriction. When the reading is taken, the thermometer leaves the human body, the mercury becomes cold and shrinks, but the mercury cannot be squeezed back from the narrow mouth smoothly.

Therefore, after the temperature drops, if the mercury column wants to return to its original position, it must have a certain pressure to smoothly pass through the narrow curved neck. This design is mainly to measure the accuracy of the temperature, to prevent the thermometer from starting to drop after leaving the body. So the doctor will shake it before taking the temperature every time to return the mercury to its original position for the next accurate measurement.

With the development of technology, digital infrared thermometer has entered ordinary households. Unlike ordinary mercury thermometers, digital infrared thermometer do not need to be clamped under the armpit. This advantage is essential for some families with newborn babies, because using an ordinary thermometer to measure the temperature of infants and children is a very laborious task, and infrared thermometers just solve this difficulty.

This digital infrared thermometer is based on the principle of infrared temperature measurement technology. In the natural world, all objects whose temperature is higher than absolute zero (minus 273.15 degrees Celsius) will radiate infrared light every moment.

The amount of infrared radiation energy of an object and its distribution according to wavelength are closely related to its surface temperature, which is the basis of infrared temperature measurement technology.

Digital infrared thermometer is composed of optical system, photodetector, signal amplifier, signal processing and display output. The optical system collects the infrared radiation energy of the target. The energy is focused on the photodetector and then converted into the corresponding signal. Converted into the temperature value of the measured target.

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aijj
Joined: June 6th, 2019
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