Name: Ramya Sethuram
Affiliation: Indian Institute of Astrophysics
Conference ID : ASI2022_764
Title : Conceptual Design of Wide Field Optical Spectrograph for TMT
Authors : Ramya, S., Sivarani, T., Sriram, S., Devika, D., Amirul H., Harimohan, V., Sudarshan, K., Ajin Prakash, Govinda, K. V., Viswanatha, N.
Abstract Type: Invited
Abstract Category : Instrumentation and Techniques
Abstract : The Wide-field Optical Spectrograph (WFOS) is a seeing-limited, near-UV, visible, near-IR imaging and multi-object spectrograph (MOS) being designed as a first light instrument for the Thirty Meter Telescope (TMT). The spectrograph design has gone through the Conceptual Design Phase and is expected to end in February 2022. The optical design provides two color channels, spanning the 310–550nm and 550-1000nm passbands, and a combination of gratings, filters, and mirrors to enable direct imaging and three spectroscopic modes with resolutions of 1500, 3500, and 5000 in both color channels using precision cut slit masks, providing a field of view ~25 arcmin^2. India has been contributing significantly to the design of WFOS since 2014 -leading the mechanical design of spectrograph mechanisms, namely, grating exchanger and camera articulation systems, Opto-mechanical design of Calibration system, electronics and instrument control software, thus contributing 1/3rd of the total effort towards design and development of WFOS. In this presentation, I will talk about the gravity invariant vertical rotation axis optical design that incorporates the latest developments in grating and coating technologies to provide a high throughput spectrograph that can cater to a wide variety of science cases ranging from IGM tomography to exoplanet atmospheres. I will also present the design of each of the subsystems of WFOS focussing mainly on India’s contributions and discuss a few science cases where an instrument like WFOS will play a significant role.