Beyond the Visible: Near-IR vs. Thermal Imaging

Jason Tsai, Edmund Industrial Optics

For some machine vision applications, you need to see more than what can be seen with the naked eye. Low-light or poor-contrast conditions may give cause to consider vision systems that image beyond the visible spectrum. Various types of data that cannot be detected by standard vision systems, such as heat emission and materials defects, can be obtained by imaging in the infrared. Extending into this part of the spectrum can offer a number of advantages, but each region of the infrared has its own benefits and requirements.

Although the near-IR and thermal IR regions both lie within the infrared spectrum, they use wavelengths that are an order of magnitude apart. For perspective, consider that the entire visible spectrum covers wavelengths only from about 400 to 700 nm. All the wavelengths from about 700 nm to 14 µm, however, are considered infrared...