Form 9.B Project Summary

Chron: 972170

Proposal Number: 15.01-9233

Project Title: Multidither Sensing for Wavefront Control

Technical Abstract (Limit 200 words)

Attractive concepts for space-based telescopes with large apertures include thin stiffened membranes and assemblies of lightweight mirror segments. Either may be quite stable at rest, but disturbances can produce small distortions that would degrade optical performance if uncorrected, and means must be provided to accurately sense and position to the tolerances required for phase coherence. Hartmann sensing or shearing interferometry have generally been used in the past with ground-based adaptive optics systems, and phase retrieval techniques have recently been proposed for NASA’s NGST program, but all require a relatively bright distant object, the first two effectively measure the local tilt instead of the displacement itself, all require intensive computations to produce the needed result, and phase retrieval may not converge to the correct result. Unlike those techniques which seek to determine and then to correct the wavefront, this proposal is based on the all-but-forgotten "multidither" approach that unambiguously maximizes the intensity of the image itself by individually "tagging" corrective elements with small high-frequency piston oscillations and then adjusting those segments until those frequency components vanish. Sirius proposes to resurrect this promising technique, using high-speed electronics, logic, and detectors to overcome its early faults and to exploit its strengths.

Potential Commercial Applications (Limit 200 words)

Multidither sensing for wavefront correction promises the use of commercially available components and relatively simple electronic hardware, it does not require a separate "beacon" as a reference source, and it provides an unambiguous solution for maximizing intensity in the focal plane. As such, it offers significant economic and performance benefits to the astronomical community, ranging from very large space-based telescopes to the amateur community, and to the potentially massive communications industry for both ground-based receivers and laser transmitters.

Name and Address of Principal Investigator (Name,

Organization Name, Mail Address, City/State/Zip)

Dr. Glenn W. Zeiders

The Sirius Group

108 Spinnaker Ridge Drive SW

Huntsville , AL 35824

Name and Address of Offeror (Firm Name, Mail Address,

City/State/Zip)

Dr. Glenn W. Zeiders

The Sirius Group

108 Spinnaker Ridge Drive SW

Huntsville , AL 35824