Control algorithms developed for coarse phasing the segmented mirrors of the Next Generation Space Telescope (NGST)are being tested in realistic modeling and on the NGST wavefront control testbed, also known as DCATT.

space↗

NASA NTRS2000

Telescope Simulator for the Nexus Wavefront Control Testbed

A telescope simulator was built as part of the Nexus wavefront control testbed, an NGST technology experiment at NASA's Goddard Space Flight Center.

NGST↗

NASA NTRS2000

Calculation of Diffraction Effects on the Average Phase of an Optical Field

The present paper reports on algorithms for the computation of the average phase of a beam over a detector in the near field.

diffraction diffraction modeling space interferome↗

NASA NTRS2000

Performance of the NGST Wavefront Control System as Tested on DCATT

The NGST wavefront control testbed (also known as DCATT) is being used to map out the accuracy and dynamic range of the baseline NGST wavefront control system.

wavefront control large optics wave front sensing ↗

NASA NTRS1999

DCATT Dispersed Fringe Sensor (DFS) -- Modeling and Experiment with Transmissive Phase Plates

The alignment and phasing control of NGST's segment primary mirrors use images from the science camera instead of dedicated instruments.

Wavefront sensing wavefront correction dispersed f↗

NASA NTRS1999

Controlling the DCATT/NEXCAT Hardware

Explore the source record for details and available documents.

DCATT/NEXCAT NGST hardware↗

NASA NTRS1999

NGST Wavefront Control: Lessons Learned from DCATT and Nexu

Explore the source record for details and available documents.

NGST Wavefront Control NGST Lessons DCATT Nexu↗

NASA NTRS1998

Adaptive Optics Reconstruction Utilizing Super-Sampled Deformable Mirror Influence Functions

This paper describes adaptive optics control laws that are now being implemented on the Palomar Mountain Hale telescope. This system uses a Shack-Hartman sensor observing natural guide stars to drive a 241 active-actuator deformable mirror and a fast steering mirror.

Adaptive↗

NASA NTRS1998

Retroreflector Diffraction Modeling

The SIM metrology subsystem utlizes cornercube retroreflectors as fiducials.

retroreflectors↗

NASA NTRS1998

Infrared Telescope Technology Testbed Primary Mirror Test Results

An 85 cm aperture beryllium mirror was fabricated as part of the Infrared Telescope Technology Testbed (ITTT), a facility to which the SIRTF flight telescope will be traceable.

SIRTF↗

NASA NTRS1998

Wavefront Sensing and Control for a Next Generation Space Telescope

The Next Generation Space Telescope will provide more than ten times the collecting area of the Hubble Space Telescope in a package that fits into the shroud of an expendable launch vehicle. This paper illustrates the operation and performance expected for initial telescope alignment, segment phasing, and fine figure control for the NGST yardstick design.

wavefront↗

NASA NTRS1998

Retroreflector Diffraction Modeling for SIM

A retroreflector is an optical device that reflects light (visible, UV, or IR) in the direction where it came from.

retroreflector diffraction SIM UV IR↗

NASA NTRS1997

Next Generation Space Telescope Integrated Performance Modeling

The main points of focus in this presentation are the integrated modeling, optical control timeline, optical control algorithms, and optical performance of the next generation of space telescopes.

space telescope optical control next generation↗

NASA NTRS1995

Mirror Birefringence in a Fabry-Perot Cavity and the Detection of Vacuum Birefringence in a Magnetic Field

We discuss the effect of mirror birefringence in two optical schemes designed to detect the quantum-electrodynamics (QED) predictions of vacuum birefringence under the influence of a strong magnetic field, B. Both schemes make use of a high finesse Fabry-Perot cavity (F-P) to increase the average path length of the light in the magnetic field. The first scheme, which we called the frequency scheme, is based on measurement of the beat frequency of two orthogonal polarized laser beams in the cavity. We show that mirror birefringence contributes to the detection uncertainties in first order, resulting in a high susceptibility to small thermal disturbances. We estimate that an unreasonably high thermal stability of ~10-9 K is required to resolve the effect to 0.1%. In the second scheme, which we called the polarization rotation scheme, laser polarized at 45 relative to the B field is injected into the cavity.

Vacuum Birefringence↗