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Residual speckles due to aberrations arising from optical errors after the split between the wavefront sensor and the science camera path are the most significant barriers to imaging extrasolar planets. While speckles can be suppressed using the science camera in conjunction with the deformable mirror, this requires knowledge of the phase of the electric field in the focal plane. We describe a method which combines a coronagraph with a simple phase-shifting interferometer to measure and correct speckles in the full focal plane. We demonstrate its initial use on the Stellar Double Coronagraph at the Palomar Observatory. We also describe how the same hardware can be used to distinguish speckles from true companions by measuring the coherence of the optical field in the focal plane. We present results observing the brown dwarf HD 49197b with this technique, demonstrating the ability to detect the presence of a companion even when it is buried in the speckle noise, without the use of any standard "calibration" techniques. We believe this is the first detection of a substellar companion using the coherence properties of light., Comment: 32 pages, 11 figures. Accepted for publication in MNRAS

Low-loss (1.4-cm(-1)) single-mode rib waveguides in Al(x)Ga(1-x)As heterostructures are fabricated by liquid phase epitaxy, double anodization, and photolithographic techniques. Switching of optical channels between adjacent waveguides is accomplished with directional coupler switches controlled with electrodes laid over an isolating dielectric, making a metal-oxide-semiconductor (MOS) configuration. Complete switching is achieved with20 V applied to a stepped Deltabetareversal electrode configuration. A 2 x 4 switching matrix with low-loss lateral offsets of the waveguides is demonstrated. By laying out several optical switching and guiding experiments within a 128-mum stripe, we show that independent optical circuits can be packed with adequate optical isolation using centerline separations approximately 10 microm.

Breaking gravity waves are studied in a wave tank at small grazing angles (4.5/spl deg/-11/spl deg/) where all four polarization elements (HH, VV, HV, VH) are simultaneously measured. Temporally averaged Doppler spectra are obtained for mechanically-generated 4 m breaking waves of various energies. The authors describe the dependence on breaking-wave energy of the parameters describing the backscatter. The results of grazing angle dependence of the backscatter are also shown and discussed.

The non-circular shape of the Keck telescopes primary mirror, combined with the fact that the telescope is on an alt/az mount with the adaptive optics system on the left Nasmyth platform, means that as the telescope tracks a star field the hexagonal pupil image rotates on the wavefront sensor camera and on the deformable mirror. This creates a need for a dynamic control strategy. The control matrix, the list of which subapertures are sufficiently illuminated and the list of which actuators are active and which are slaved, all must change on the fly, with the loops closed and without perturbing a science observation in progress. This control strategy must also be robust in the presence of modest pupil translation. These needs are met in the Keck AO system by the Pupil Rotation Compensation (PRC) software tool. The PRC software is responsible for maintaining system parameters that are functions of the pupil position and orientation. This paper will present the details of the PRC software design including algorithms used for selecting active subapertures, dealing with variable subaperture illumination, calculating control matrices, and slaving actuators outside the pupil illuminated area on the deformable mirror.

The wavefront controller for the Keck Observatory AO system consists of two separate real-time control loops: a tip-tilt control loop to remove tilt from the incoming wavefront, and a deformable mirror control loop to remove higher-order aberrations. In this paper, we describe these control loops and analyze their performance using diagnostic data acquired during the integration and testing of the AO system on the telescope. Disturbance rejection curves for the controllers are calculated from the experimental data and compared to theory. The residual wavefront errors due to control loop bandwidth are also calculated from the data, and possible improvements to the controller performance are discussed.

The Adoptics software used with the Hooker telescope's ADOPT adaptive optics system implements real-time control on a network of eight Texas Instruments C40 40Mhz DSP processors. System inputs and outputs consist of a 32 port 4 fiber wavefront sensor CCD with 32 X 32 pixels, a tilt mirror and a deformable mirror of which 241 elements are actively controlled. The network os eight DSP processors is configured as two cross-connected rings of four processors each. Four input sites perform intensity and gradient calculations immediately on incoming pixels as well as passing pixels on to adjacent sites for parallel calculations.

The Multiple Mirror Telescope on Mt. Hopkins will soon be upgraded to a single 6.5 m primary mirror.An adaptive- optical system, featuring a thin-shell, adaptive-secondary mirror with 330 voice-coil actuators is being developed for this new telescope. The thin-shell mirror is supported by a thick, concave aluminum substrate which also holds the actuator control and monitoring electronics and serves as the reference surface. With the actuator electronics dissipating heat into the substrate, the thermal behavior of the aluminum reference plate becomes as important issue. This paper presents results form tow experiments designed to determine the thermal behavior of the reference plate.

The cassegrain adaptive optics system (ADOPT) on the Mount Wilson 100-inch telescope has been in operation now since June of 1995. This report chronicles the ongoing performance improvements, the drive towards unassisted use by visiting observers, and some significant science results of this system. The last includes: observations Mira with its companion and other red giants, many observations of asteroids, and the satellites of Jupiter and Saturn, the planets Uranus and Neptune, and of course, double stars. Objects with magnitudes from V=0.0 to V=13.7 have served as natural guide stars, with no change in optics or filters needed over this range. Resolution of 0.07 arcsec is routine on a bright object in good seeing, with 0.058 arcsec at B band as the best performance to date. Coronagraphic and spectroscopic additions are planned for the system.

In January 1994, we began construction of a modern adaptive optics system for the newly refurbished 100-inch telescope. The design philosophy of the adaptive optics system is to achieve a working system in the visible in a short time at relatively low cost. This means wavefront sensing with natural guide stars and implementation at the bent Cassegrain focus of the telescope. The system has an integrated wavefront sensor and finder camera, and is automated for one-person operation. It uses off-the-shelf components where possible. The deformable mirror, which has 241 actuators, is on loan from the U.S. Air Force. The use of an existing mirror imposes constraints that have driven some of the design considerations. The system is operating at the telescope, with early results described below.

We have mounted an early adaptive optics system, the Atmospheric Compensation Experiment (ACE), on the 60-inch telescope at Mount Wilson Observatory in California in a program designed to investigate the performance of ACE at an astronomical site and to evaluate the usefulness of adaptive optics for astronomy. Despite its development as a non-astronomical instrument, ACE has produced positive results, including the obtaining of images of single and double stars with a resolution (full-width half-maximum) of 117 milliarcseconds at 700 nm. Improvement of image quality is obtained for guide objects with a B magnitude brighter than 5.9. To deepen this limiting magnitude, we have embarked on a low-noise high-speed CCD fabrication project jointly with JPL. First devices have been fabricated. We have applied post- processing techniques borrowed from speckle methodology to the adaptive optics images, and find that the pre- and post-processing techniques complement each other powerfully. We conclude that an adaptive optics system designed specifically for visible-wavelength astronomy would be a low-order system with good site thermal control, combined with post-processing. Such a system could be effective, robust and relatively low cost.

In this paper, we describe TRW's latest version of the scanning laser slope gauge (SLSG) which was used to characterize the sea surface in a recent ocean experiment. The SLSG, capable of measuring the spatial distribution and temporal evolution of the surface slopes of a patch of ocean, provides ground truth data which form a quantitative basis for the understanding of ocean wind-wave interactions and the development and validation of radar scattering models relevant to ocean remote sensing.

A three-color IR photometer suitable for speckle imaging or for traditional fast or slit-scan photometry is described, with special attention given to the photometer's scanning and relay optics, the dewar, the electronics, and the data acquisition and reduction hardware and software. The system is able to acquire sets of object and sky scans on three colors simultaneously, while concurrently performing a Knox-Thompson speckle analysis on the incoming data. The slit-scan photometry operation mode allows observations of objects too faint for speckle imaging. To date, the system was used to observe more than 20 T Tauri stars, several evolved stars, numerous binaries, and G29-38, with good agreement with published and known results for binary observations and those of NML Cyg and IRC + 10216.

The transmission properties of single‐heterostructure GaAs‐AlxGa1−xAs rib waveguides (RWG) clad with thin anodized oxides (0–200 A) covered by gold (MOS structures) are investigated both theoretically and experimentally. Efficient polarizers having extinction ratios of 35 dB and insertion losses

Metal-oxide-semiconductor rib waveguides are low loss for any polarization and are efficiently electrooptically modulated. We show COBRA switching of 90% with 15 V and a 2 × 4 switch matrix. These suggest versatile applications in integrated optical circuits.

Metal-oxide-semiconductor rib waveguides are low loss for any polarization and are efficiently electrooptically modulated. We show COBRA switching of 90% with 15 V and a 2 x 4 switch matrix. These suggest versatile applications in integrated optical circuits.