A conceptual design for the Thirty Meter Telescope alignment and phasing system

Troy, Mitchell; Chanan, G. A.; Michaels, Scott; Bartos, Randy; Bothwell, G.W.; Give’on, Amir; Hein, Randy; Radin, Maxwell D.; Roberts, J. T.; Rodgers, J. Michael; Scherr, L.; Seo, Byoung-Joon; Zimmerman, D.

doi:10.1117/12.788560

Cited by 19 publications

(9 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Troy-2008. 5 The largest source of error in the mirror alignment is from the atmosphere. The APS measurement errors are based on data from the Phasing Camera System (PCS) 6 of the Keck Telescopes scaled for TMT and also a separate MACOS modeling activity as seen in Ref.…”

Section: Segment Piston Tip and Tilt Errorsmentioning

confidence: 99%

“…We approximate the atmosphere through a Zernike decomposition as proposed by Chanan using an integration time of 600 seconds. 5 Previous modeling work 7 has generated a set of Zernike covariance matrices to simulate the AO correction of this time-averaged atmosphere. Using these covariance terms, we scale the time-averaged Zernike coefficients and pass them to a Matlab routine used to calculate segment rigid-body motion to simulate this corrected atmospheric surface.…”

Section: Segment Piston Tip and Tilt Errorsmentioning

confidence: 99%

See 1 more Smart Citation

High-resolution optical modeling of the Thirty Meter Telescope for systematic performance trades

et al. 2008

Self Cite

View full text Add to dashboard Cite

We consider high-resolution optical modeling of the Thirty Meter Telescope for the purpose of error budget and instrumentation trades utilizing the Modeling and Analysis for Controlled Optical Systems tool. Using this ray-trace and diffraction model we have simulated the TMT optical errors related to multiple effects including segment alignment and phasing, segment surface figures, temperature, and gravity. We have then modeled the effects of each TMT optical error in terms of the Point Source Sensitivity (a multiplicative image plane metric) for a seeing limited case and an adaptive optics corrected case (for the NFIRAOS). This modeling provides the information necessary to rapidly conduct design trades with respect to the planned telescope instrumentation and to optimize the telescope error budget.

show abstract

Section: Segment Piston Tip and Tilt Errorsmentioning

confidence: 99%

Section: Segment Piston Tip and Tilt Errorsmentioning

confidence: 99%

High-resolution optical modeling of the Thirty Meter Telescope for systematic performance trades

et al. 2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…The desired set-point for the sensors is determined every 2-4 weeks with optical wavefront information using the Alignment and Phasing System (APS). 7 Sensor installation errors result in some cross-sensitivity to gap and shear motions between neighbouring segments; the gaps are also measured, and shear (imperfectly) estimated, and this used together with APS information to calibrate out the cross-sensitivity. In addition to the quasi-static gravity and thermal deformations controlled at Keck, M1CS at TMT will provide some reduction of the response to wind turbulence forces over M1.…”

Section: Introductionmentioning

confidence: 99%

Control system modeling for the Thirty Meter Telescope primary mirror

MacMynowski

Thompson

Shelton

et al. 2011

Integrated Modeling of Complex Optomechanical Systems

View full text Add to dashboard Cite

The Thirty Meter Telescope primary mirror is composed of 492 segments that are controlled to high precision in the presence of wind and vibration disturbances, despite the interaction with structural dynamics. The higher bandwidth and larger number of segments compared with the Keck telescopes requires greater attention to modeling to ensure success. We focus here on the development and validation of a suite of quasi-static and dynamic modeling tools required to support the design process, including robustness verification, performance estimation, and requirements flowdown. Models are used to predict the dynamic response due to wind and vibration disturbances, estimate achievable bandwidth in the presence of control-structure-interaction (CSI) and uncertainty in the interaction matrix, and simulate and analyze control algorithms and strategies, e.g. for control of focus-mode, and sensor calibration. Representative results illustrate TMT performance scaling with parameters, but the emphasis is on the modeling framework itself.

show abstract

“…First, the edge sensors are modified to report segment-to-segment gap, as well as the height difference, to give observability to the in-plane segment positions. Second, the telescope is aligned, or "phased", using the Alignment and Phasing System (APS) on bright stars, 9,10 at a sufficient set of zenith angles and temperatures. Third, a "calibration procedure" is applied.…”

Section: Introductionmentioning

confidence: 99%

Advances in edge sensors for the Thirty Meter Telescope primary mirror

et al. 2008

Self Cite

View full text Add to dashboard Cite

The out-of-plane degrees of freedom (piston, tip, and tilt) of each of the 492 segments in the Thirty Meter Telescope primary mirror will be actively controlled using three actuators per segment and two edge sensors along each intersegment gap. We address two important topics for this system: edge sensor design, and the correction of fabrication and installation errors.The primary mirror segments are passively constrained in the three lateral degrees of freedom. We evaluate the segment lateral motions due to the changing gravity vector and temperature, using site temperature and wind data, thermal modeling, and finite-element analysis.Sensor fabrication and installation errors combined with these lateral motions will induce errors in the sensor readings. We evaluate these errors for a capacitive sensor design as a function of dihedral angle sensitivity. We also describe operational scenarios for using the Alignment and Phasing System to correct the sensor readings for errors associated with fabrication and installation.

show abstract

A conceptual design for the Thirty Meter Telescope alignment and phasing system

Cited by 19 publications

References 3 publications

High-resolution optical modeling of the Thirty Meter Telescope for systematic performance trades

High-resolution optical modeling of the Thirty Meter Telescope for systematic performance trades

Control system modeling for the Thirty Meter Telescope primary mirror

Advances in edge sensors for the Thirty Meter Telescope primary mirror

Contact Info

Product

Resources

About