Bengaluru-based Hind High Vacuum (HHV), leaders in vacuum and thin film technology, has bagged a contract from Physical Research Laboratory (PRL), a unit of Department of Space, Government of India, for manufacture and installation of a dedicated mirror coating plant for the latter’s upcoming 2.5-meter telescope.

This telescope is a part of the Mount Abu Observatory, located at the Gurushikhar Peak of Mount Abu, Rajasthan, at an altitude of about 5,600 feet above mean sea level, a spokesman for HHV said here on Monday.

Fundamental research

The Physical Research Laboratory was founded in 1947 by Vikram Sarabhai, and carries out fundamental research in physics, space and atmospheric sciences, astronomy, astrophysics and solar physics and planetary and geo-sciences.

The mirrors of the telescopes are amongst the most important components for sensing radiations from distant sources. These need to be coated with a reflective thin film that aids efficient light collection, the spokesman pointed out.

The reflective coatings are prone to environmental degradation which necessitates a re-coating. Existing coatings are stripped clean, and a fresh coating is then applied. These coatings are applied by vacuum deposition process to obtain the best properties in terms of reflectivity and durability.

Vacuum deposition process

As the mirrors are sensitive, and one of the most expensive components in the telescope assembly, the coatings are carried out on-site. Thus, a vacuum coater is stationed on-site astronomical observatories for coating of the mirror at regular intervals, the spokesman explained.

He quoted Prasanth Sakhamuri, Managing Director, HHV, as saying that astronomical telescopic mirrors coaters require a technologically advanced high vacuum equipment design, engineering, and manufacturing. “HHV has been globally recognised as a trusted supplier for coaters for telescopic mirrors and has demonstrated its coaters at various locations including demanding high altitudes going up to about 14,800 feet.”

Telescope mirrors of size of up to 3,700 mm diameter and weighing more than 4,000 kg can be accommodated in HHV coating chambers with a maximum overall dimension of 4,000×2,100 mm. The coaters offer an automated and highly reliable process for coating mirrors with aluminium and/or silver-based coatings.

National, international clients

HHV is the supplier of the coating plant for several organisations in India and across the world such as the Indian Institute of Astrophysics, Inter-University Centre for Astronomy and Astrophysics, Aryabhatta Research Institute of Observational Sciences, and Observatory of the Sternberg Astronomical Institute, Moscow State University, Russian Federation.

Last year , HHV was short-listed by the Thirty Meter Telescope (TMT) International Observatory and India TMT Coordination Committee to develop the conceptual design of the coater for secondary and tertiary mirrors of their upcoming telescope. TMT is a joint venture between scientific institutions in Canada, China, India, Japan, and the US to build a 30 m diametre optical infra red telescope, which will be one of the largest optical telescopes ever built.

Expertise in niche area

HHV is currently executing an order from Physical Research Laboratory, Udaipur, for building a mirror coater for handling mirrors of different sizes going up to a maximum of 700 mm diameter. This re-emphasizes HHV’s technical competency in this niche area, the spokesman added.

HHV is continually taking up development activities in this area to integrate its coaters with proven process recipes for the deposition of highly reflective and durable thin film coating stacks, he added.

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