Mirrors, lenses: Science behind Surya Tilak of Ram Lalla on Ram Navami

The ‘Surya tilak’ of Ram Lalla in Ayodhya was done at noon on Wednesday on Ram Navami factoring in detailed calculations of the Sun’s position and using an elaborate mechanism involving mirrors and lenses by which sunbeams were directed on the forehead of Ram idol.

The Indian Institute of Astrophysics, Bengaluru, an autonomous body under the department of science and technology, played a crucial role in the Surya Tilak project.

“Sunlight was directed onto the forehead of Sri Ram Lalla at 12 noon on April 17, 2024, on the occasion of Sri #RamNavami in the Chaitra month, and this ritual will be repeated every year,” Abhay Karandikar, secretary of the department of Science and Technology, government of India, posted on X.

In a series of posts on X, Karandikar, former director of IIT Kanpur, explained how the project was executed by a team of IIA, Bengaluru and experts of the Central Building Research Institute, Roorkee.

The team led by IIA, Bengaluru, carried out calculations of the Sun’s position, designed and optimized the optical system, and performed the integration and alignment at the site, Karandikar said.

“As the temple is not fully completed now, the IIA experts modified the design to suit the existing structure and performed image optimization. This design, with four mirrors and two lenses, was executed for the Surya Tilak,” added Karandikar.

“The final design of the Surya Tilak, with four mirrors and four lenses, will be implemented once the full temple is constructed by placing the mirrors and lenses in their permanent fixtures,” Karandikar added.

“The English calendar date of Sri Ram Navami festival changes every year as it follows Lunar calendar. Therefore, the position of the sun in the sky changes every year on the day of Sri Ram Navami,” he said.

“Detailed calculations show that the English calendar date of Sri Ram Navami repeats every 19 years. Calculating the position of the sun in the skyon these days requires expertise in astronomy,” he added.

The team led the estimation of the size, shape and location of mirrors and lenses in the system for sufficient light to fall on the idol for about six minutes.

“Opto-mechanical design of the lens and mirror holder assembly, and manual mechanism were carried out to shift the position of the first mirror according to the position of the Sun in the sky,” Karandikar said.

This helped the entire system to work flawlessly for the Surya Tilak to be carried out successfully. The device was manufactured by Optica, Bangalore, and the implementation of the opto-mechanical system at the site was being done by the CBRI, Roorkee, Karandikar posted on X.