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.

Electronics Bazaar - - Contents - 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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