Photon sieve: the future of ultralight space telescopes?

A diffractive space-telescope primary could be made of an unfurlable thin film.

July 27, 2016

Sending a telescope into space comes at a high price, for more than one reason. Launching the Hubble Space Telescope was costly because it was heavy, due in part to its massive, rigid primary mirror and mirror mount. Building the James Webb Space Telescope, let alone launching it, is costly not only due to its weight, but also the fact that it needs a massive, intricate, and expensive mechanism to allow it to unfold and then keep its various parts aligned in space.

This drawing shows the difference between a Fresnel zone plate (left) and a photon sieve (right). The latter is patterned with millions of precisely machined holes.

Example 2. Etched into a silicon wafer, the photon sieve shown below is a lab test device developed at NASA’s Goddard Space Flight Center (Greenbelt, MD); it is a miniature prototype of a future 1-m-diameter photon sieve that could one day be used in space to image the Sun at UV wavelengths. While this photon sieve brings red laser light to a pinpoint focus on its optical axis, it produces exotic diffraction patterns when viewed from the side, as seen here.

About the Author

John Wallace

Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.