| Name: Athul C N |
| Affiliation: Indian Institute of Technology, Kanpur |
| Conference ID: ASI2026_491 |
| Title: Development of a Shack–Hartmann–Based Atmospheric Turbulence Monitor and Profiler |
| Abstract Type: Poster |
| Abstract Category: Facilities, Technologies and Data science |
| Author(s) and Co-Author(s) with Affiliation: Athul C N(Indian Institute of Technology Kanpur), Prashant Pathak(Indian Institute of Technology Kanpur) |
| Abstract: Characterization of atmospheric optical turbulence is essential for the design and efficient operation of modern ground-based optical telescopes. The Differential Image Motion Monitor (DIMM) has long served as the standard instrument for measuring atmospheric seeing; however, it provides no information on other key turbulence parameters such as the atmospheric coherence time or the vertical distribution of optical turbulence strength. These parameters are critical for the successful design and operation of adaptive optics systems on large ground-based telescopes.
This work presents the development of a turbulence monitor and profiler that extends the DIMM concept by exploiting differential image motion measurements of bright stars using a Shack–Hartmann wavefront sensor in place of the traditional two-hole aperture mask. This approach, implemented in the Shack–Hartmann Image Motion Monitor (SHIMM), enables robust seeing estimates that are largely insensitive to shot noise and scintillation effects. In addition to seeing, SHIMM provides a low-resolution (three-layer) estimate of the vertical turbulence profile and an independent measurement of the atmospheric coherence time.
SHIMM is designed as a low-cost, portable instrument built entirely from off-the-shelf components, making it straightforward to replicate and suitable for deployment at remote sites. An end-to-end simulation and analysis framework has been developed to model the instrument and to quantify the response of Shack–Hartmann spot motion to atmospheric turbulence. We present the algorithmic framework, simulation results, and preliminary on-sky measurements demonstrating the instrument’s performance.
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