A thermal imaging camera works by detecting and measuring the infrared radiation or the heat energy emitted by objects and representing it in the form of an ‘image’ or a ‘thermograph’ (also known as thermogram). This is done using a special camera lens and an imaging sensor that is sensitive to frequencies in the infrared region of the electromagnetic spectrum.
The imaging or heat sensors are constructed as a grid of pixels, which convert the infrared wavelengths hitting them into electronic signals. The signals are then processed into a color map of different temperature values and gradients within the main body of the camera. The color map is displayed on the screen and can be used for further analysis.
The thermal camera generates images of infrared radiations that are invisible to the naked eye into a visible image, which is why the process of thermal or infrared imaging is also known as “invisible imaging”.
Eight Features and Specs to Consider
There are certain key features and specs of thermal cameras that you should consider before selecting one to meet your needs:
Resolution: A higher detector resolution means more pixels on the IR imaging camera. Improved spatial resolution means a larger field of view, while a lower spatial resolution value means better faster image processing and dynamic image rendering.
Focus: There are various focus mechanisms such as
Fixed focus: A simple mechanism of ‘point and shoot’.
Manual focus: Allows you to focus your thermal camera manually and precisely.
Autofocus: Automatically focuses on a target but may require manual adjustment for higher precision.
Laser-assisted autofocus: Uses a built-in laser distance meter to calculate the distance from the target and focuses accordingly.
Multifocal mechanism: Captures and stores multiple images of the target from different focal distances and blends them into one high-precision finely detailed image using computer software.
Temperature range: Choose a thermal camera with a temperature range similar to that of your target so that it can capture the highest as well as the lowest temperatures in the image. For multifunctional applications, choose a camera with a wide temperature range that can automatically select the range based on your target, or allows you to set the range manually.
Lens: There are lenses for various applications such as standard, wide angle, telephoto, and macro lens. Depending on your need, choose a lens that best serves the purpose of capturing the right area of view with the best resolution. Some thermal cameras also allow you to change lenses based on the type of operation or the target.
Memory and sharing: Select a memory that can store the IR images such as a removable SD card, or a USB flash drive. Certain thermal cameras can also connect to WiFi and Bluetooth for sharing and backup of data, portable analysis, and report generation.
Color palettes: Some color palettes help bring out certain details that other colors may miss. Slight differences are easier to see with a monochromatic palette, such as grayscale or amber. While monochromatic colors such as grayscale or amber are good for detecting slight differences in temperature, high contrast color palettes can easily detect obvious anomalies.
Color alarms and spot markers: Color alarms can be used to highlight areas outside the normal temperature range of your target objects. Spot markers mark specific temperatures on the thermal image to compare simultaneous temperatures across different points.