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Researchers have created a new smaller, lighter design for high-resolution imaging spectrometers in space. These high-dispersion imaging spectrometers could be used to analyze the Earth’s atmosphere or the atmospheres of other planets aboard spacecraft or satellites.
The new research will be presented by James P. McGuire, Jr. of NASA’s Jet Propulsion Laboratory in Southern California at the Optica Design and Fabrication Conference, which will be held June 4-8, 2023 in Quebec City, Canada.
“This spectrometer has the same measurement capabilities as conventional designs, but it is one-tenth the size and mass, and it is also less expensive.” Smaller, lighter, and less expensive open the door to new applications and markets,” McGuire explained.
Imaging spectroscopy, also known as hyperspectral imaging, collects information for each pixel in an image of a scene spanning the electromagnetic spectrum. It is generally employed from space to monitor solids or liquids that require great spatial resolution and low spectrum resolution. However, there is a need for smaller and lighter-weight space-based imaging spectrometers that collect atmospheric data with high spectral resolution and low spatial resolution.
The researchers discuss near-infrared (NIR) and long-wave infrared (LWIR) imaging spectrometer systems that could assist fulfill this gap in their new paper. The spectrometer designs incorporate desirable features from several existing designs, such as an immersed grating that reduces the grating size by as much as the refractive index, a Littrow optical configuration that uses the same optics before and after the grating, and a grating on a spherical surface to simply correct an optical error known as Petzval field curvature. Gratings divide white light into its constituent color spectrum.
The researchers designed a NIR imaging spectrometer with 2,048 spectral pixels and 512 spatial pixels with an aperture of f/1.9 that covers a spectral range of 2302 nm to 2370 nm. They also created an LWIR version with 1536 spectral pixels and 256 spatial pixels at f/1.7 using various materials.
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