| Authors : | List of Authors:
Janmejoy Sarkar (1, 2)*, Ravi Kesharwani (1), Ankala Raja Bayanna (3), Melvin K. James (4), Soumya Roy (1), Sreejith Padinhatteeri (1, 5), A.N. Ramaprakash (1), Durgesh Tripathi (1), Rushikesh Deogaonkar (1), Bhushan Joshi (1), Chaitanya V. Rajarshi (1), Deepa Modi (1), Nidhi Mehandiratta (1), Bhargavaram B. S. (6), Mandeep Kiran (6), Vishweshwar Rao B. (6), Venkateswaran R. (6), Sankarasubramanian K. (7), Nigar Shaji (7)
*Presenting Author
Affiliations:
1. Inter-University Centre for Astronomy and Astrophysics, Pune, India.
2. Tezpur University, Tezpur, India.
3. Udaipur Solar Observatory, Udaipur, India
4. Nayam Innovations Pvt. Ltd., Pune, India.
5. Manipal Centre for Natural Sciences, Manipal, India.
6. Laboratory for Electro Optics Systems, Bengaluru, India.
7. U.R. Rao Satellite Center, Bengaluru, India. |
| Abstract : | The Solar Ultraviolet Imaging Telescope (SUIT) is an off-axis Ritchey–Chrétien telescope onboard India’s first dedicated space solar observatory, Aditya-L1. It is built for full disk observations of the Sun in the 200-400nm wavelength range from the Sun-Earth Lagrange-1 point.
The chief optical components of SUIT include a primary mirror, a secondary mirror, a field corrector lens, and the CCD detector. In addition to this, the filter wheel assembly, thermal filter, shutter, and baffles are used to get a good image within the required spectral band. These components require intricate alignment to achieve the targetted image quality of 80% encircled energy in 2x2 pixels. The mounts of each component are designed to meet the tight mass budget of the payload leading to limited degrees of freedom for their movement, making the optical alignment a non-trivial and challenging task.
The dependence of the Zernike parameters on each degree of freedom is first simulated in Zemax. Assisted by a Fizeau Interferometer, similar adjustments are made iteratively in the optical components to minimize the wavefront errors till they are close to the modeled values. This is repeated for both the flight model and qualification model of SUIT. The qualification model of SUIT is used as a collimator to perform optical tests on the flight model. The Point Spread Function (PSF) recorded from SUIT is convolved with high-resolution solar images to simulate the onboard performance of the payload.
In this presentation, we illustrate the methodology developed for the alignment and integration of SUIT, the simulations employed to facilitate it, the optical quality after alignment, and the envisioned performance of SUIT during its tenure of observing the Sun.
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