Infrared Camera

Unlike conventional visible light cameras that create images using the visible spectrum, thermal cameras operate in the infrared spectrum because all objects above absolute zero temperature emit thermal radiation energy. This fundamental principle allows infrared cameras to detect and visualize heat differences in a scene.

In an infrared camera, an optical lens system focuses thermal variations from the thermal emissions onto a detector array. This array consists of numerous pixels, each corresponding to a specific area in the scene. The intensity of infrared radiation detected by each pixel indicates the object’s temperature at that location. Depending on the infrared wavelength spectrum being used, the sensor detectors in these cameras may utilize different technologies, such as bolometers or infrared photodetectors.

When infrared radiation from objects within the infrared camera’s field of view strikes the detector, it changes the electrical properties of the sensor material, such as impedance, in most uncooled infrared cameras, which rely on uncooled bolometers. The absorbing element of bolometers is typically made of a material whose electrical resistance changes significantly with temperature. As the temperature of the absorbing element increases, its electrical resistance changes. In other cases, infrared cameras use semiconductor material that converts infrared light into an electrical current. Those operate based on the quantum effect, where photons incident on the photodiode’s surface generate electron-hole pairs. These infrared devices must be cooled to very low temperatures to achieve low noise, requiring more maintenance and higher costs.

The camera’s electronics amplify, digitize, and process these signals to generate a visual image. In most infrared cameras, a shutter mechanism periodically calibrates the sensor array by correcting for offset and non-uniformity, ensuring accurate intensity measurements.

The software within the camera processes the digitized signals by applying calibration data to translate the infrared radiation intensity into temperature values. This translation allows for precise non-contact temperature measurements, enabling temperature control, temperature analysis, and alarm triggering based on predefined thresholds.

Infrared cameras are not one-size-fits-all. They are available with various spectral ranges, measurement ranges, speeds, sensitivities, and resolutions, tailored to a wide range of application requirements and budget constraints. For instance, some cameras are designed to detect long-wave infrared radiation, which is invaluable for certain industrial applications, while others might be optimized for mid-wave infrared radiation, which is better suited for different environmental conditions. This adaptability ensures that there’s an infrared camera for every need.

The performance and capabilities of an infrared camera are determined by several factors. Spectral range refers to the specific portion of the infrared spectrum the camera is sensitive to, which impacts its suitability for different applications. Measurement range defines the range of temperatures the camera can accurately measure. Speed refers to how quickly the camera can capture and process images, critical for applications involving fast-moving objects or real-time monitoring. Sensitivity denotes the camera’s ability to detect minute temperature differences, which is essential for high-precision applications. Resolution determines the clarity and detail of the thermal images, with higher resolutions providing more detailed and accurate temperature data.

To select the appropriate infrared camera for a specific application, it is essential to consider the specific needs and constraints of the use case. For industrial applications, factors such as environmental conditions, required measurement accuracy, and the specific temperatures to be measured are critical. Additionally, the choice between cooled and uncooled infrared cameras can impact performance and cost. Cooled cameras, which use a cryogenic cooling system to enhance sensitivity and resolution, are more expensive and complex but provide superior performance in demanding applications. Uncooled cameras, on the other hand, are more cost-effective and robust, making them suitable for a broader range of applications.