Study of tilt axis bearing arrangement for M3S of TMT project

Zhao, Hongchao; Zhang, Jingxu; Yang, Fei; An, Qichang; Su, Yan-qin; Guo, Peng

doi:10.1117/12.2068924

Cited by 2 publications

(1 citation statement)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The final design of the Rotator structure is illustrated in Figure 4. Due to the volume requirement of GSSM to stay within the obscuration shadow of the M2, the Tilt Assembly needs a compact design [3] . In addition, the angle between the Tilt axis and the gravity varies from 0 to 90°.…”

Section: Introductionmentioning

confidence: 99%

Pre-construction progress of giant steerable science mirror for TMT

Yang

Zhao

et al. 2016

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

The Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) team is developing the Giant Steerable Science Mirror (GSSM) for Thirty Meter Telescope (TMT) which will enter the preliminary design phase in 2016. The GSSM is the tertiary mirror of TMT and consists of the world's largest flat telescope mirror (approximately 3.4m X 2.4 m X 100mm thick) having an elliptical perimeter positioned with an extremely smooth tracking and pointing mechanism in a gravity-varying environment. In order to prepare for developing this unique mirror system, CIOMP has been developing a 1/4 scale, functionally accurate version of the GSSM prototype during the pre-construction phase of GSSM.The prototype will incorporate the same optomechanical system and servo control system as the GSSM. The size of the prototype mirror is 898.5mm×634mm×12.5mm with an elliptical perimeter. The mirror will be supported axially by an 18 point whiffletree and laterally with a 12 point whiffletree. The main objective of the preconstruction phase includes requirement validation and risk reduction for GSSM and to increase confidence that the challenge of developing the GSSM can be met. The precision mechanism system and the optical mirror polishing and testing have made good progress. CIOMP has completed polishing the mirror, the prototype mechanism is nearly assembled, some testing has been performed, and additional testing is being planned and prepared. A dummy mirror is being integrated into the cell assembly prototype to verify the design, analysis and interface and will be used when testing the prototype positioner tilt and rotation motions. The prototype positioner tilt and rotator structures have been assembled and tested to measure each subsystem's jitter and dynamic motion. The mirror prototype has been polished and tested to verify the polishing specification requirement and the mirror manufacturing process. The complete assembly, integration and verification of the prototype will be soon finished. Final testing will verify the prototype requirements including mounted mirror surface figure accuracy in 5 different orientations; rotation and tilt motion calibration and pointing precision; motion jitter; and internally generated vibrations. CIOMP has scheduled to complete the prototype by the end of July 2016. CIOMP will get the sufficient test results during the pre-construction phase to prepare to enter the preliminary design for GSSM.

show abstract

Section: Introductionmentioning

confidence: 99%

Pre-construction progress of giant steerable science mirror for TMT

Yang

Zhao

et al. 2016

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

show abstract

Estimation of the GSSM calibration error

et al. 2016

View full text Add to dashboard Cite

The calibration of the tertiary mirror of the Thirty Meter Telescope, also known as the giant science steering mirror (GSSM), is a step of great significance during its testing process. Systematic, drift, and random errors constitute the major limitations to the accuracy of the calibration measurements. In this article, we estimated the errors in the calibration of the GSSM with a laser tracker. For the systematic error, a measurement strategy based on the standard bar method was successfully designed and applied. At the same time, we can distinguish between the drift and random errors by means of a correlation analysis. The systematic error, which depends strongly on the configuration of the system formed by the GSSM and the laser tracker, was estimated to be 20 μm for the GSSM prototype. The random error, averaging 15 min, was about 4 μm. The correlation coefficients among three different noise measurements are all lower than 0.1, which indicates that the noise is dominated by random errors. Finally, the error can be sufficiently suppressed by rearranging the position of the spherically mounted retroreflectors. The result shows that the accuracy of the measurement can be improved by 21.4% with the new arrangement method.

show abstract

Study of tilt axis bearing arrangement for M3S of TMT project

Cited by 2 publications

References 4 publications

Pre-construction progress of giant steerable science mirror for TMT

Pre-construction progress of giant steerable science mirror for TMT

Estimation of the GSSM calibration error

Contact Info

Product

Resources

About