What Is Spectral Imaging?

Mary McMahon

Spectral imaging is an imaging technique that can provide information about a sample beyond what the observer can see on the visible spectrum. In this process, devices capable of detecting and recording radiation outside the visible spectrum can pick up information from a specimen and return it in a form meaningful to the operator, like a graph of the chemical signatures in a cell. This technique is used in scientific research, medical practice, and military theory, and there are a number of systems users can utilize in spectral imaging.

Man holding computer
Man holding computer

Equipment available for spectral imaging can be highly variable, depending on which spectra people wish to look at and what they want to do with the data. Telescopes, spectroscopy equipment, cameras, and a variety of other sensors are employed in the collection of spectral data. Sophisticated computer programs can interpret, smooth, and present data in a variety of formats for the benefit of users.

In multi-spectral imaging, the device picks up information from several different spectra and can separate it out for the user. Thus, a user might look at visual information as well as data from the infrared spectrum and other spectra of interest. This can be useful in fields like botany, where researchers may compare the visual appearance of a flower with its infrared or ultraviolet signature to understand how it attracts and signals insects and other animals.

One application for spectral imaging is in surveying, where imaging equipment can be flown over an area of interest. In addition to picking up visual data, it can identify specific chemical signatures of interest as well as other forms of radiation. This may allow the operator to do anything from identifying human beings to radioactive materials. Military organizations use this technique to identify targets and collect intelligence information.

In physics, spectral imaging can be a very valuable tool for the collection of information. It can generate a three dimensional image, where each pixel of the visual image also has accompanying spectral data. Researchers can use that data to identify things like x-rays and other radiation, tell-tale signs of activity that may not be visible. This can be useful for understanding the formation of the universe, or analyzing samples of unknown material.

Biologists use spectral imaging to pick up unique chemical signatures in samples from cells to water. It can also be useful in forensics, where very precise spectral data can allow technicians to match paint chips or to learn more about the source of a specimen. The images generated may have false colors coded for ease of reading, and it is important to be aware of this when looking at a spectral image. What appears red in the image, for instance, is not actually red.

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