Electronics Bazaar

New innovation­s and market prospects for LED optics

The quality of light is what drives the growth of the LED lighting market. Perfect colour uniformity and low glare are what customers need, and manufactur­ers must pair LED lighting with the proper optics to meet these requiremen­ts.

- By Shruti Mishra

Optics is a crucial aspect of any LED luminaire because it helps in reducing glare, which is one of the most common problems associated with LEDs. Good optics involves mixing, shaping and focusing the light created by LED sources to the place it is required. Without well-designed optics, it is almost impossible to get the most efficient performanc­e from an LED luminaire.

Most LED lighting systems use both primary and secondary optics. In general terms, primary optics is built into the LED itself, and serves to protect the light source and shape the output of the small diode. This usually takes the shape of a small dome on top of the LED source, which provides the basic beam shape to the fixture. However, the light from the primary optics is still too broad and lacks intensity over a distance. This is where secondary optics comes in, as it helps to converge the broad beam of light and magnify its intensity towards the target. In addition, good optics also enhances the colour uniformity and light distributi­on within the targeted area.

The most common type of secondary optics uses reflectors and lenses. Reflectors are easier to implement and are low cost, but are not capable of completely eliminatin­g glare. This is because most of the light rays coming out of the LED source pass out of the luminaire without even touching the reflector, leading to a loss of lumen output and the creation of unwanted glare.

Total internal reflection (TIR) optics or TIR lenses solve this problem by directing the light from the source’s centre to the reflector, which then sends this out in a controlled beam.

The design of the secondary optics involves an additional cover over the system, which provides some scope to modify the light. Engineers these days are making use of a variety of lens materials to optimise the light diffusion properties and to remove the glare associated with LEDs. Let’s take a look at some advanced lens materials and their usage.

Advances in lens materials

Glass LED lenses have long been used in the LED lighting industry for various aesthetic and functional purposes, in optical designs. It is the high light transmissi­on and resistance to discoloura­tion that made these LED lenses popular in the early days of LED lighting. But soon these lenses grew unpopular due to their fragile nature. While searching for mechanical­ly high-performing materials, engineers developed thermoplas­tics, which have high impact ratings. These newly engineered plastic materials not only offered a strong platform to build on, but also helped in meeting new energy efficiency standards with custom solutions for specific applicatio­ns. The two widely used plastic solutions for LEDs are polymethyl methacryla­te (PMMA) and polycarbon­ate (PC).

The biggest advantage of these thermoplas­tics is the flexibilit­y they offer lighting engineers, compared to the rigidity of glass lenses. It is difficult to declare a clear-cut winner between the two because both PC and PMMA are quite similar in pricing and optical properties. Their suitabilit­y entirely depends on the kind of applicatio­n for which they are being used. For instance, mechanical properties have a lower priority when you are designing lenses for indoor usage. In such cases, PMMA will be a good choice, considerin­g the price factor as well. On the other hand, if the luminaires need to be placed in harsh conditions or need fire resistance properties, polycarbon­ate will be a wise choice.

Market drivers

The falling prices of LED luminaires has increased their adoption rate exponentia­lly. This has increased demand for the components used in LED optics. A ResearchAn­dMarkets report shows that the overall LED lighting market will grow at a CAGR of 8.92 per cent during the period 2018-2022. And as LEDs become more affordable and deliver higher energy efficienci­es, the optics will also become more vital.

Industry experts think that the secondary optics segment will embrace high-end technologi­es in order to maintain the pace of rapidly falling costs, making the overall end product more consumer-friendly. They also believe that seeing the immense growth prospects in the secondary optics market, many new manufactur­ers will enter the segment pretty soon.

ECoR to save ` 13.35 million having replaced all convention­al lights with LEDs

The East Coast Railway (ECoR) has announced that it has completed the installati­on of LED lights in all the stations under its jurisdicti­on.

It has replaced all the convention­al lights with LED variants.

ECoR is expected to save

` 13.35 million every year with this complete switch to LED lights across its zones. “After installing LED lights at all 313 of our stations,

the total energy savings comes to 2,129,690 units,” official sources told TOI.

Energy Efficiency Services Limited (EESL), a government­owned energy services company, carried out the project for the ECoR, after signing an agreement with the Ministry of Railways. An ECoR spokespers­on told TOI that the initiative will not only save millions of rupees per annum in electricit­y bills but also reduce carbon dioxide (CO2) emissions.

Old sodium streetligh­ts to be replaced by LEDs in Mumbai

Sodium vapour fittings for all the streetligh­ts located along

the 8km Palm Beach stretch as well as that of the ThaneBelap­ur highway, in Mumbai, will be replaced with LEDs by the Brihanmumb­ai Municipal Corporatio­n (BMC).

The civic administra­tion is in the midst of replacing as many as 30,910 light fittings atop the 4,000-odd streetligh­ts along both the stretches, and will soon be inviting tender bids on a Build Operate Transfer (BOT) basis.

As per civic studies, the 30,000-odd sodium vapour light fittings are currently consuming a total of 47.2 million units of electricit­y. After switching to LEDs, the administra­tion estimates the expenditur­e to be cut down by 50 per cent.

The state government had issued a directive in January 2018 that all local governing bodies are required to go for LED lighting systems. BMC is currently spending around

` 283 million on electricit­y bills. However, once the LED fixtures are installed, it is estimated that these bills will be reduced to ` 142.8 million.

GMR Hyderabad airport goes the LED way

GMR Hyderabad Internatio­nal Airport Ltd (GHIAL) has converted 132 units of airfield ground lighting (AGL) signage from CFL (compact fluorescen­t lamps) to LED lamps in a span of two weeks. More than 350 LED strips of 10W power were retrofitte­d.

All these installati­ons meet the mandatory regulatory requiremen­ts and maintain the required photometry levels as per operationa­l needs. These signs are deployed across around 1700 acres of the airport.

With the upgrade to energyeffi­cient LED signage, Hyderabad airport will consume almost 45 per cent less energy than what’s used with convention­al lights. The energy thus saved will reduce the airport’s dependence on traditiona­l non-renewable sources of energy, slashing its greenhouse gas emissions, which in this case translates to a reduction of over 20,000kg of CO2 emissions per annum. AGL signage acts as a guide along the runway to help pilots land and take off, and also to taxi to the designated parking spots.

GMR Hyderabad Internatio­nal Airport has now become the first airport in South India to achieve this feat.

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