Vibration budget for observatory equipment

Abstract

Abstract. Vibration from equipment mounted on the telescope and in summit support buildings has been a source of performance degradation at existing astronomical observatories, particularly for adaptive optics performance. Rather than relying only on best practices to minimize vibration, we present here a vibration budget that specifies allowable force levels from each source of vibration in the observatory (e.g., pumps, chillers, cryocoolers, etc.). This design tool helps ensure that the total optical performance degradation due to vibration is less than the corresponding error budget allocation and is also useful in design trade-offs, specifying isolation requirements for equipment, and tightening or widening individual equipment vibration specifications as necessary. The vibration budget relies on model-based analysis of the optical consequences that result from forces applied at different locations and frequencies, including both image jitter and primary mirror segment motion. We develop this tool here for the Thirty Meter Telescope but hope that this approach will be broadly useful to other observatories, not only in the design phase, but for verification and operations as well.

Management of equipment vibration for extremely large telescopes

“…To first order, TMT has tied its vibration budget to its desired adaptive optics (AO) image quality; 10 if AO performance is met then vibration will not be an issue for seeing-limited observations. TMT allocates an overall budget of 30 nm of allowable WFE to vibration.…”

Dynamic stabilization of thin aperture light collector space telescope using active rods

“…7 The pointing stability of a telescope is largely affected by the microvibrations caused due to the on-board equipment. [8][9][10] Passive vibration isolation is often used because of the issues such as reliability and low maintenance cost. [11][12][13][14] Owing to the large aperture, space limitations in the launch vehicle, and deployment mechanism, the TALC is bound to be more flexible than the previous telescopes.…”

A review on control methodologies of disturbance rejections in optical telescope

“…However, long integration time of the image sensor is always required for a high signal to noise, which restricts the closed-loop control bandwidth. Therefore, the vibrations induced by telescope structures could not be fully compensated by classical control loops 11,12 . If disturbances are measurable, it is obvious that a disturbance feedforward control strategy is the most effective way to attenuate them [13][14][15] .…”