DLideas 3: Spectroscopy

The DLideas series focuses on current developments in the world of DLP^® and emerging applications using the technology.
Spectroscopy is being used in a wide-variety of applications such as pharmaceuticals, petrochemicals, food & agriculture, manufacturing, as well as security. Spectroscopy is an effective tool for recognizing and analyzing properties and materials by measuring the variations in absorption or emission of different wavelengths of light. This can be performed using ultraviolet, visible and infrared light and samples may be materials of any of the various physical phases – solid, gas, liquid or plasma. Some samples are light-emitting, while others are light absorbing.

During spectroscopy, light is spread out into a spatially-distributed rainbow of wavelengths. The light intensity and wavelengths are compared, measured and recorded. This allows for the analysis of the recorded data in order to learn more about materials by cross-referencing with a catalog of spectral characteristics.

DLP^® technology is being utilized in spectroscopy, with the spectrum of light being spread out across the DMD micromirror array. The DMD then acts as a programmable wavelength selection filter and a dispersive optical element such as diffraction gratings or prisms are used to spatially separate the wavelengths of light. Columns of the DMD are then selectively turned on or off to select the range of wavelengths that the user wants to work with. From there, rows of the DMDs are used to attenuate these individual wavelengths.

DLP^® makes it possible to design rugged, mechanically-robust, high-performance spectrometers, as opposed to alternative methods that use rotating gratings or large expensive array detectors. Currently, large and expensive lab-based spectrometers are required to properly identify and characterize the composition of a material. Now, with DMDs, more industries can obtain affordable, portable equipment to perform real-time analysis in the field or on the assembly line.