Infrared (IR) thermal imaging, also known as infrared thermography (IRT), is a rapidly evolving field in science and industry owing to the enormous progress made in the last three decades in microsystem technologies of IR detector design, electronics, and computer science.
Thermography is a type of imaging accomplished with an IR camera calibrated to convert infrared radiation to a visual image and display temperature values across an object or scene.
An effective, convenient, and economical method for the last 30 years; it allows one to make non-contact measurements of an object’s thermal variations (from approximately 900 to 14,000 nanometers or 0.9–14 µm), invisible to human eyes.
Infrared thermography enables a simple and fast way to map the entire temperature distribution on the whole area of interest in one go. IRT provides accurate, real-time, and contactless temperature readings for several clinical and industrial applications, especially in diagnostics, inspection, monitoring, surveillance, and preventative maintenance applications.
An infrared thermographic camera detects this radiation similarly to an ordinary camera that can detect visible light. An IR camera’s main components are a lens, a detector in the form of a focal plane array (FPA), possibly a cooler for the detector, and the electronics and software for processing and displaying images.
Here is how it works. A special lens focuses the infrared light from all of the objects in view. The focused light is scanned by the infrared The focused light is scanned by the infrared-detector elements detector elements creating electric impulses. The impulses are sent to a signal processing unit that translates the information from the elements into data for the display. The signal processing unit sends the information to the display, where it appears in various colors depending on the intensity of the infrared emission.
IRT has many advantages over other technologies such as:
- IRT is non-contact. The devices are not in contact with the source of heat, making them non-contact thermometers. In this way, the temperature of extremely hot or dangerous objects can be measured safely.
- IRT provides two-dimensional thermal images, making a comparison between areas of the target possible and easy.
- IRT is real-time. It enables a high-speed scanning of stationary as well as fast-moving targets.
- IRT does not have any harmful radiation effects, which some technologies, such as X-ray imaging, have. This makes it suitable for prolonged and repeated use.
IRT is a non-invasive technique. Thus, it does not intrude upon or affect the target in any way.
- Thermal cameras can detect people, objects, and incidents in low-light environments, complete darkness, or other challenging conditions such as smoke-filled and dusty environments.
- Thermal cameras are robust and cannot be blinded by strong lights or put out of order using laser pointers.
Several parameters and factors can significantly affect the quantitative analysis and interpretation of IR images recorded with modern IR cameras systems. They are as follows:
- Emissivity of object
- The distance of the camera to the object.
- Size of object
- Relative humidity
- Ambient temperature.
- Atmospheric temperature
- External optics temperature
- External optics transmission
- The wavelength range of the camera
- Angle of observation
- Use of filters
- Thermal reflections
- Wind speed
- Solar load
- Shadow effects of nearby objects
Buying an infrared camera can be a big commitment, even though prices have fallen dramatically over the past few years. There are many choices in thermal imagers, ranging from affordable point-and-shoots to highly specialized HD-level science and research cameras. Finding the right fit for your needs, therefore, can seem daunting.
First, ask these questions when selecting an IR camera. What temperatures are you expecting to measure? How fast will you need to capture the data? What is the size and distance to your target of interest? What type of detector is best suited for your application? What kinds of temperature analysis and report generation will you need? What additional accessories will you require? What support and training options are available from the camera manufacturer?
Answering these questions will help narrow down which infrared cameras and detector types are best suited for your application. Let’s now explore some of the key things to remember while investing in an infrared camera.
- Determine the temperature range that you are expecting to measure.
- Pay close attention to detector resolution since most infrared cameras have fewer pixels than visible-light cameras. Be aware of the difference between the detector and display resolution. A high-resolution LCD does not mean a higher resolution detector.
- Find a system with a built-in, visible-light camera outfitted with an illuminator lamp and a laser pointer. Built-in LED lamp lights dark areas for better digital images while a laser pointer marks the target for visible light reference images.
- Select a camera that gives you accurate and repeatable results. Accuracy and consistency of the measurements is a very important factor when determining the value of a camera.
- Choose a camera that supports a broad range of file formats and software.
- Choose a thermal imager with a wide temperature range so you can measure ambient and high-temperature spots in the same image.
- Check if the camera can generate and send instant reports via Wi-Fi.
- Look for cameras with comprehensive, extended warranty programs like replaceable batteries to protect your investment.
- Ensure if the manufacturer provides ongoing technical support and training.