Designers devise space-based imaging spectrometers that are smaller, lighter, and possess high spectral resolution.

Researchers have developed a new, smaller and lighter design for imaging space spectrometers with higher spectral resolution. High dispersion imaging spectrometers aboard spacecraft or satellites can be used to study Earth’s atmosphere or the atmospheres of other planets.

James P. McGuire Jr. of NASA’s Jet Propulsion Laboratory in Southern California will present the new research at NASA Optics Design and Manufacturing Conferencewhich will take place from June 4-8, 2023 in Quebec City, Canada.

“This spectrometer provides the same measurement capabilities as conventional designs, but with one-tenth the size and mass and at a lower cost. Smaller, lighter and cheaper, it opens the door to new applications and markets,” McGuire said.

Imaging spectroscopy, also known as hyperspectral imaging, acquires information across the electromagnetic spectrum for each pixel in a scene image. When performed from space, it is typically used to observe solids or liquids, which requires high spatial resolution and low spectral resolution. However, smaller and lighter space imaging spectrometers that collect atmospheric information are needed, which requires high spectral resolution and low spatial resolution.

In the new work, the researchers describe near infrared (NIR) and long wave infrared (LWIR) imaging spectrometer designs that could help fill this need. Spectrometer designs combine desirable features from many existing designs, including an immersed lattice that reduces the lattice size as much as the refractive index, a Littrow optical configuration that uses the same optics before and after the lattice, and grating on a spherical surface merely to correct for an optical error known as Petzfall field curvature . Follicles separate white light into its component color spectrum.

The researchers developed a design for NIR imaging spectrophotometer covering a spectral range from 2302 nm to 2370 nm with 2048 spectral pixels and 512 spatial pixels with an f/1.9 aperture. Using different materials, they also designed an LWIR version covering 8 µm to 12 µm with 1,536 spectral pixels and 256 spatial pixels at f/1.7.