NASA puts lenses through a different drill to stare at the Sun
19th century optics gets the 21st century treatment
NASA Goddard boffins and engineers have taken inspiration from the Fresnel lens to craft a “photon sieve” they hope will help them observe the processes that heat the sun's corona.
The diffraction that gives a Fresnel lamp its soft edges is also handy for gathering light. NASA's post here explains that after passing through the plate, the light waves “reinforce or cancel each other out in precise patterns”.
In the “photon sieve” Goddard's engineers have replaced the alternating clear/opaque glass of a Fresnel plate with holes that match the Fresnel zones.
Their three-inch test lenses contain 16 million holes in a layout designed by Goddard's Adrian Daw, while fellow team member Kevin Dennis photolithographically etched that design onto a silicon wafer.
Eventually, the NASA team hopes to scale up the photon sieve to a one-metre diameter lens tuned to the ultraviolet, so as to capture better detail of the sun's corona. This, they say, would help research into the physical processes behind the heating of the corona – something that needs 100 times better angular resolution than is available from the NASA Solar Dynamics Observatory.
Fresnel lens design left, photonic sieve right. Image: NASA
To see if the photon sieve is ready to take to space, the group hopes to test the technology on a sounding rocket mission, and perhaps to hoist a payload on a CubeSat launch. ®