Why do we need to add a lens in front of the infrared temperature sensor?

肖柳子

Why do we need to add a lens in front of the infrared temperature sensor? [Copy link]

Looking at the infrared thermometer products on the market, why is there an elongated black cylinder in front of the temperature sensor, and a lens inside? Is it for measuring farther?

chunyang

There are two common types of infrared temperature measurement, one based on thermopile sensors and the other based on infrared-sensitive image sensors. The black object in front is an infrared filter, which is used to filter out-of-band interference such as visible light, and the meaning of the lens is different for the two types of sensors. Generally, no lens is added in front of the thermopile sensor. If it is added to gather light and improve the receiving sensitivity, then it can be said that it is "in order to measure farther", but not only that, adding a lens can also measure the temperature of heat sources with smaller radiation areas. However, for the latter, that is, the infrared image sensor, the meaning of the lens is different. The imaging sensor must image the measured area on the sensor. Taking a photo is one thing, but it cannot be said that it is "in order to measure farther" because it cannot work without a lens. In addition, the lenses and installation requirements of the two are fundamentally different. The latter is more appropriately called a "lens".

maychang

In order to image the object to be measured on the sensor.

肖柳子

maychang posted on 2020-9-25 18:19 In order to image the object to be measured on the sensor.

Increase the measuring distance

Gen_X

The long tube is of course designed to reduce the measuring angle, making it easier to distinguish objects at a longer distance.

Some lenses are used to filter out the influence of visible light, while others are used to focus light and improve measurement sensitivity.

After all, infrared can cause greater damage at a "long distance".