Speaker
Description
The Wide Field Optical Spectrometer (WFOS) is an instrument under development for the first-light operation of the Thirty Meter Telescope (TMT), which will provide high throughput across the entire wavelength range of 310-1000 nm, including the extreme blue and red wavelengths. In order to achieve that, the design has a two-channel spectrograph layout, a red and a blue channel. Each channel has a separate grating, camera & detector system.
The grating exchanger is required for both red & blue channels to exchange the gratings for low, medium & high-resolution modes and filters for image mode. The rotation angles for the gratings/filters are different for each mode. The main challenge in designing the grating exchanger is the space constraint due to several other optomechanical systems requiring different gratings/filters to facilitate various observing modes. The allocated time budget for exchange to switch between observing modes is also a critical challenge that limits serial operations. In addition, it is essential to maintain the position and angular accuracy of placement of the grating in its place. The same is to be maintained through its expected functional life of about 50 years, considering the wear and tear of the moving elements.
Different trade-off design studies have been done to reach the conceptual design of the grating exchanger. The final conceptual design has 5 degrees of motion for exchanging the gratings/filters. The trade-off designs and finalized conceptual design of the grating exchanger, including calculations and kinematic assessment, will be presented in this talk.
| Presentation type | Oral |
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