If you ever took a class in practical physics that included a lab, then you remember those little diffraction gratings that could be used as a substitute for a prism to observe the spectrum of light. The gratings exhibited the properties of prisms, but without the bulk. If you did not happen to have a physics lab, then you may remember those flat Fresnel (pronounced ‘freh-nel’) fish-eye lenses that were popular in the back windows of vans and motor homes. Again, the properties of a larger, bulkier lens made in a compact format.
Image: (L. Koechlin et al/OMP) – a metallic prototype of a diffraction lens – click on the image for a larger view.
Now, it appears that a diffraction grating is being considered as a lightweight, and even more accurate, optical device for focusing light without the usual mirrors and lenses. That will be a boon for the future of space and even terrestrial telescopes.
This excerpt from New Scientist explains how that is possible.
