Nanosatellite System Could Lower Cost of High-Resolution Space Imagery

A new nanosatellite imaging system developed by Ben-Gurion University (BGU) researchers is able to capture high-resolution images at far less cost than the full-frame, lens-based, or concave mirror systems used on today’s telescopes.

The researchers used a digital holographic system, called a synthetic marginal aperture with revolving telescopes (SMART) system. SMART is based on the concepts of synthetic aperture imaging and interferenceless coded aperture correlation holography.

An illustration of the SMART nanosatellite. The new nanosatellite system captures better imagery at lower cost. Courtesy of Ben-Gurion University of the Negev.

This synthetic aperture-based imaging system has two physical subapertures distributed along the perimeter of the synthetic aperture only. The optical configuration is based on a setup in which two synchronized satellites move only along the boundary of the synthetic aperture and capture a few light patterns from the observed scene. The light reflected from the two satellites interferes with an image sensor located in a third satellite. The sum of the entire interfering patterns is processed to yield the image of the scene with a quality comparable to an image obtained from a complete synthetic aperture.

The system uses the incoherent coded aperture holography technique in which the light diffracted from an object is modulated by a phase mask. The modulated light is recorded and digitally processed to yield the 3D image of the object.

To demonstrate the SMART system capabilities, the researchers built a miniature laboratory model with a circular array of subapertures to study the image resolution and compare it with full lens imagery. The researchers then contrasted these images to those produced by direct imaging systems, which have similar dimensions of the whole aperture and are based on a layout of annular subapertures.

Experimental results validated that sampling along the boundary of the synthetic aperture was enough to yield an image with the same resolution obtained from the complete synthetic aperture. The researchers said that with the SMART system, there is no need to sample any other part of the aperture beside its border. They believe that this could generate a significant savings of time and/or devices needed for image acquisition.

Researcher Angika Bulbul, working under the supervision of professor Joseph Rosen, said that the BGU study proves that by using a partial aperture, even a high-resolution image can be generated. This could reduce the cost of traditionally large telescopic lenses.

“We found that you only need a small part of a telescope lens to obtain quality images,” Bulbul said. “Even by using the perimeter aperture of a lens, as low as 0.43 percent, we managed to obtain similar image resolution compared to the full aperture area of mirror/lens-based imaging systems. Consequently, we can slash the huge cost, time, and material needed for gigantic traditional optical space telescopes with large curved mirrors.”

The research was published in Optica, a publication of OSA, The Optical Society (https://doi.org/10.1364/OPTICA.5.001607).