The UN marks the International Day of Light (IDL) — an annual initiative held globally to raise awareness on the critical role played by light-based technologies in everyday life.

The IDL as mentioned in the news creates no scope for a possible prelim question, but the purpose behind its celebration does.  i.e. LASER technology. LIDAR is the latest development in the LASER technology. UPSC may puzzle you here by asking the working principle of LIDAR.

International Day of Light (IDL)

• The IDL is administered from the International Basic Science Programme (IBSP) of UNESCO, and its Secretariat is located at the Abdus Salam International Centre of Theoretical Physics (ICTP) at Trieste, Italy.
• The IDL highlights the contribution of such technologies in various avenues such as science, technology, art, and culture, thus helping achieve the UNESCO goals of education, equality, and peace.
• The day selected, May 16, marks the anniversary of the first successful operation of the LASER in 1960 by physicist and engineer Theodore Maiman.
• The LASER is a perfect example of how a scientific discovery can yield revolutionary benefits to society in communications, healthcare and many other fields.

Why is the IDL celebrated?

• In 2015, to raise global awareness of the achievements of light science and its applications, the UN observed the International Year of Light and Light-based Technologies 2015 (IYL 2015).
• The event helped establish links and collaborations between decision-makers, industry leaders, scientists, artists, social businesses, NGOs, and the public at large.
• Following the success of IYL 2015, Ghana, Mexico, New Zealand and Russia placed a resolution before the UNESCO Executive Board supporting the idea of an International Day of Light.
• It was adopted on September 19, 2016, at the Board’s 200th session at the UNESCO HQ in Paris, France.
• The Board decision was endorsed by the UNESCO General Conference at its 39th session on November 7, 2017, and the first IDL was held on May 16, 2018.

Back2Basics: LASER

• A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation.
• It is an acronym for “light amplification by the stimulated emission of radiation.
• The laser stimulates atoms or molecules to emit light at particular wavelengths and amplifies that light, typically producing a very narrow beam of radiation.
• The emission generally covers an extremely limited range of visible, infrared, or ultraviolet wavelengths.
• Many different types of lasers have been developed, with highly varied characteristics.
• A laser is widely used in industrial cutting, surgical removal of tissues etc.
• LIDAR is the most famous application of LASERs.

LiDAR (Light Detection And Ranging)

• It is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth.
• It bounces pulsed laser light off the ground, revealing contours hidden by dense foliage.
• These light pulses—combined with other data recorded by the airborne system— generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.
• LIDAR systems allow scientists and mapping professionals to examine both natural and manmade environments with accuracy, precision, and flexibility.
• A LIDAR instrument principally consists of a laser, a scanner, and a specialized GPS receiver.
• Airplanes and helicopters are the most commonly used platforms for acquiring LIDAR data over broad areas.

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