What is Spectroscopy?
Spectroscopy is the study of how electromagnetic radiation (e.g. visible light, heat) is absorbed or reflected by matter. Historically, spectroscopy has been key in chemical analysis, and through comparison of known materials' spectra, unknown materials could then be identified. Today's uses continue along this line, utilizing the unique reflectances of measured matter to further understand composition of matter on earth and in our universe.
What is a Spectroradiometer?
A spectroradiometer is a device that can precisely and accurately measure the magnitude of reflected light from organic and inorganic materials. It works by shining a beam of light onto the material, and interpreting which wavelengths are reflected back onto the sensor inside the machine. The spectrum of wavelengths that are able to be measured by these devices range from short (blue) to long (infrared) wavelengths; determining these wavelengths allows us to assign various materials unique spectral signatures.
What is a Spectral Signature?
Everything that we can touch or see has a unique spectral signature, which is the amount of light an object reflects, and the specific wavelengths that it reflects and absorbs. Reflectance is a variable largely dependent on the chemical composition of something, as well as something's physical state. Due to spectral signatures being unique, an object or piece of matter has a spectral "barcode" or "fingerprint" that can be used to identify the material through the use of a spectroradiometer.
To the right is an example of a spectral signature for the lichen Cladonia stellaris.
To the right is an example of a spectral signature for the lichen Cladonia stellaris.
Applications of Spectroscopy
By studying each pixel of a remote sensing image taken from the air, we can analyze the spectrum that was captured in that pixel area and then rely on our library to determine what lichens are growing in that particular area. This is done by comparing the spectrum of the pixel to the spectrum's from our library. This is a much more effective way of performing aerial surveying. Once we have the library compiled, we will no longer have to go to the actual sites to learn about the types of lichen growing there. This will save a lot of time and money in the long run.