Jeffrey T. Baker

Self-Synchronous and Self-Referenced Coherent Beam Combination for Large Optical Arrays

A novel and highly accurate electronic technique for phase locking arrays of optical fiber amplifiers is demonstrated. This is the only electronic phase locking technique that does not require a reference beam. The measured phase error for this system is lambda /20. A model for calculating the signal-shot noise-limited phase errors and the phase-modulation-induced phase errors is developed. For the first time, nine fiber amplifiers are coherently combined. The total power in the phase locked array is 100 W.

On the use of dual frequency nematic material for adaptive optics systems: first results of a closed -loop experiment.

The use of liquid crystal devices for wavefront control has been suggested and implemented by several authors. In this paper we report some preliminary results on the use of Nematic based liquid crystal devices. Several experimental efforts have been carried out in the past few months. One of the main aims was to characterize a new device that uses dual frequency nematic material in a closed loop arrangement.

Non-mechanical zoom system

In order to optically vary the magnification of an imaging system, mechanical zoom lenses, such as those found on 35mm cameras, require multiple optical elements and use cams or gears to adjust the spacing between individual or groups of lenses. By incorporating active elements in the optical design, we can eliminate the need to change lens separations and create an imaging system with variable optical magnification that has no macroscopic moving parts.

Holographic compensation of severe dynamic aberrations in membrane-mirror-based telescope systems

Real-time holography compensates for severe aberrations in membrane-mirror based telescope systems. Laboratory demonstrations in both imaging and beam projection have been conducted. Prototype optically addressed liquid-crystal spatial light modulator devices, developed and adapted for this application, are demonstrated with significantly improved diffraction efficiencies.

Liquid crystal technology for adaptive optics: an update

The idea of using liquid crystal devices as an adaptive optics component has been proposed by several authors. In recent years a vigorous research effort has been carried out, and it is still flourishing, in several countries. Mainly the research and experimental work has been concentrated in the USA, U.K. and Russia. There are several reasons why liquid crystals may represent a valid alternative to the traditional deformable mirror technology that has been used for the past two decades or so. The main attractiveness of LC resides in the cost. Current deformable mirror technology has a range of price going from

EAGLE: relay mirror technology development

2K to

Progress report of USAF Research Laboratory liquid crystal AO program

15K per channel. LC technology promises to be at least a couple of orders of magnitude cheaper. Other reasons are connected with reliability, low power consumption and with a huge technological momentum based on a wide variety of industrial applications. In this paper we present some preliminary characterizations of a new, large format device. Such devices have the potential for extremely high-resolution wave-front control due to the over 10,000 corrective elements. The characterization of the device, so far, consists of measurements of the overall optical quality and of the phase control relationship

Kilometer scale primary collector telescopy

EAGLE (Evolutionary Air & Space Global Laser Engagement) is the proposed high power weapon system with a high power laser source, a relay mirror constellation, and the necessary ground and communications links. The relay mirror itself will be a satellite composed of two optically-coupled telescopes/mirrors used to redirect laser energy from ground, air, or space based laser sources to distant points on the earth or space. The receiver telescope captures the incoming energy, relays it through an optical system that cleans up the beam, then a separate transmitter telescope/mirror redirects the laser energy at the desired target. Not only is it a key component in extending the range of DoDs current laser weapon systems, it also enables ancillary missions. Furthermore, if the vacuum of space is utilized, then the atmospheric effects on the laser beam propagation will be greatly attenuated. Finally, several critical technologies are being developed to make the EAGLE/Relay Mirror concept a reality, and the Relay Mirror Technology Development Program was set up to address them. This paper will discuss each critical technology, the current state of the work, and the future implications of this program.

Electronic phasing of high power fiber amplifier arrays

In this paper we present a status report of our liquid crystal (LC) adaptive optics program. Liquid crystal have been proposed to be used for adaptive optics components by several authors. We are actively pursuing a two prong approach, on one side we have built a closed loop test bed based on a 127 element nematic LC device; on the other side we are actively involved in research on the ferroelectric side of the LC devices. In this paper we present preliminary results from our testbed. The essential elements of this testbed are a Shack-Hartman based wavefront sensors with an analog reconstructor, and the 127 nematic elements from Meadowlark Optics. Some of the basic experimental parameters will be reviewed, and result will be discussed. Furthermore we will present the status of our activity in the field of ferroelectric LC. Several prototypes are under testing to establish their capabilities as AO components.

Wide-field-of-view foveated imaging system using a liquid crystal spatial light modulator

We present an improved model for a spectrographic survey telescope with a kilometer scale diffraction grating collector. Refining the initial public disclosures, the new model quantifies flux collection for telescopes of this type. An option in the new model allows a trade of reduced spectral bandwidth for increased flux collection. We provide experimental evidence to demonstrate an earlier prediction of Ångstrom spectral resolution with relaxed tolerances for grating flatness, and we show how this model is extensible in two dimensions.