Optical modeling for dynamics and control analysis

Redding, David C.; Breckenridge, W. G.

doi:10.2514/3.20745

Cited by 40 publications

(12 citation statements)

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“…4) q q q, -q, is a linear function of translational and rotational displacement of the three mirrors and of the focal plane for the small displacement of the optical elements (Redding, Breckenridge, 1991). The parameters of this function depend on the ray trace of the telescope (Fig.…”

Section: Modellingmentioning

confidence: 99%

End-to-end simulation of the image stability for the airborne telescope SOFIA

et al. 2000

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To provide astronomers access to infrared wavelength unavailable from the ground the airborne telescope SOFIA is in development. This paper focuses on the image stability of the telescope, its modelling and simulation. The operation ot the telescope under the harsh environmental conditions in the aircraft makes the prediction of the image stability during the design process necessary. For this purpose an integrated mathematical simulation model, which includes the optics. the structural dynamics and the control loops has been constructed. Because of the high relevance of the structural dvnamics for image stability and control design. special attention is paid to the Import and reduction of the finite element model of the telescopes mechanical structure. Different control approaches are considered for the attitude control and the compensation of the impact of the structural flexibility on the image motion. Additionally the secondary mirror servo-mechanism is utilized to optimize the image stability. Simulation results are shown.

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Section: Modellingmentioning

confidence: 99%

End-to-end simulation of the image stability for the airborne telescope SOFIA

et al. 2000

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“…The direction SPIE Vol. 1489 Structures Sensing and Contro/(1991) / 205 of the ray reflected from the surface is given by i=R I (5) where R is the "reflection dyadic" R=I-2NN (6) and the normal at the point of incidence is R= unit(o + Mj') (7) Perturbations in the incoming ray or in the surface attitude and position change the outgoing ray state. COMP represents perturbed rays in terms of small ray direction perturbations di, transverse aberration or "beamwalk" y,and OPD dL ( Fig.…”

Section: Rms Wavefront Erroimentioning

confidence: 99%

“…We take the segi'5 to b in segment coordinates, so that each is in the form Xsegi [e 0y Oz x y ]T (9) C is thus an array of partial derivatives relating the ray OPDs to element perturbations alrayi aLrayi aeseg2 aoseg7 c= (10) Lrayn aLrayn aeseg2 asegi Details of the derivation of C are available in Ref. 7.…”

Section: Rms Wavefront Erroimentioning

confidence: 99%

<title>Segmented mirror figure control for a space-based far-IR astronomical telescope</title>

et al. 1991

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For segmented large mirrors to be used effectively for astronomy they must be actively aligned and controlled to extreme levels of precision. We consider the figure control problem for a spaceborne far-IR telescope, the Precision Segmented Reflector Project Focus Moderate Mission Telescope. We propose a two-stage approach. A figure initialization controller is used to achieve initial phasing and alignment of the telescope using an imaging science detector. A figure maintenance controller keeps the telescope aligned during normal operation using a laser metrology optical truss sensor system. We show that performance of any figure control system is subject to limits on the controllability of the wavefront. Maintenance controllers are additionally limited by considerations of the observability of the wavefront from the maintenance sensors. We show preliminary results for the figure initialization controller. We present a "Wavefront Compensation" method for figure maintenance control that minimizes wavefront errors due to misalignment errors.

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“…A fast coordinate-free ray tracing algorithm (Redding & Breckenridge 1991) forms the basis of the OM. Diffraction propagation is handled either by numerical approximation of the Rayleigh-Sommerfeld integral or by Fourier-optical methods based on the Fast Fourier Transform (FFT).…”

Section: Modeling Interferometer Opticsmentioning

confidence: 99%

Modeling the imaging process in optical stellar interferometers

Schöller¹,

Wilhelm

Koehler³

2000

Astron. Astrophys. Suppl. Ser.

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Abstract. Optical interferometers on the ground, like ESO's Very Large Telescope Interferometer (VLTI) and the Keck Interferometer, and in space, like the InfraRed Space Interferometer (IRSI/Darwin) and the Space Interferometry Mission (SIM), will bring a major breakthrough in optical and near-infrared high angular resolution astronomy at the beginning of the next millennium. These instruments are complex systems with an exceptionally interdisciplinary character involving active/adaptive optics, structural mechanics, control engineering, electronics and various environmental disturbances (e.g. atmospheric turbulence and absorption, wind, seismic noise). For their design and development an approach from two sides is appropriate: laboratory testbeds are used for experimental investigations while numerical modeling tools perform an End-to-End instrument simulation. We have developed a set of numerical modeling tools to simulate the dynamic imaging process of an interferometer. The time-dependent point spread function (PSF) mainly characterizes the imaging performance of the instrument. It is computed by an optomechanical model. Based on the knowledge of the PSF the image of an incoherently radiating extended object is computed using a Fourier optical method. This article describes the modeling approach including an extension to more than two interferometric beams. Some results of simulations on the VLTI as a representative example are shown.

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Optical modeling for dynamics and control analysis

Cited by 40 publications

References 0 publications

End-to-end simulation of the image stability for the airborne telescope SOFIA

End-to-end simulation of the image stability for the airborne telescope SOFIA

<title>Segmented mirror figure control for a space-based far-IR astronomical telescope</title>

Modeling the imaging process in optical stellar interferometers

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