Light-emitting diodes (LED) are one of the most important innovations of the 21st century. This advanced lighting technology offers numerous benefits, including long life, responsiveness, energy efficiency, accurate color performance, and eco-friendliness. Optical design and LED lighting applications are virtually limitless, including automotive lamps, traffic signals, interior and exterior lighting, and aviation lighting.
However, LED lighting does have its limitations, including its efficacy over distances and operational costs. Optical design is a critical component of achieving LED lighting that’s less expensive and more effective.
Why Are LEDs Popular?
LEDs are energy-efficient and versatile, lending to their popularity. Here are some of the advantages of LED lighting:
- Energy Efficiency: By far, LED lighting’s most significant advantage is its energy efficiency over conventional lighting. LED bulbs can use up to 90 percent less energy than halogen or incandescent bulbs.1
- Longevity: LED bulbs have a longer lifespan compared to conventional lighting. Incandescent bulbs last about 1,000 hours, while LED lighting has an average lifespan of around 50,000 hours.
- Cost-Effectiveness: Because LED lighting consumes less energy and lasts longer than other lighting, it can save a lot on energy bills.
- Eco-Consciousness: LED lighting doesn’t have toxic materials like fluorescent lighting, which contains mercury.
- Versatility: LED lighting comes in various designs, types, and colors, whether for home décor or industrial projects.
LED Optics
An LED often has a primary optic, a protective dome that protects and shapes its output. This light is broad and not applicable to many uses because it lacks concentrated intensity at a distance. Because of this, most LED lighting uses secondary optics, such as reflectors or lenses to capture light and magnify its intensity.
Lenses and reflectors for LEDs are different from lenses for other lighting sources; LED lights emit light differently and must have appropriate optics.
For example, incandescent bulbs illuminate 360 degrees, but LED lights are directional and only illuminate (at most) 180 degrees. This is primarily because of the design of the LED, which contains one or more die mounted to a thermally conductive material. The primary optic encloses the die, so the maximum angle an LED can emit is 180 degrees.
Primary Optic
The primary optic refers to the light coming from the LED, or the center’s shape and spread of illumination. LEDs only emit in the forward direction from the center point, and the intensity won’t necessarily be the same across the entire field. The light is stronger in the center, much like other light sources.
In addition, the LED concentrates much of the luminous intensity along the center axis, which loses intensity as it moves farther away. To counter this, a secondary optic is necessary to maximize LED lights’ intensity, brightness, and efficiency.
Secondary Optics
LEDs have incredible potential for a wide range of applications in the future. Many of the current applications face barriers to delivering the desired intensity to the intended area. The light isn’t focused enough for some applications.
Secondary optics can be used to direct the light into a nearly collimated, focused beam that can reach the desired intensity in the intended area. Secondary optics can also be used to improve light distribution or color uniformity.
Total Internal Reflection (TIR) Optics
TIR optics are injected-molded polymer optics that use a refractive lens instead of a reflector. These are highly effective in controlling and reflecting LED light emissions.
Typically, these optics direct light from the center of the LED to the reflector, which then emits a reshaped beam. The beam can be adjusted to be wide or narrow, and textured surfaces in the assembly can modify the light, such as adding a frosted effect or shaping the light distribution. Also, a weak diffuser can be added to hide the structure of the LED source from the viewer.
Applications for LEDs
Signals/Indicators
One of the earliest successful LED lighting applications is as a signal or indicator. Examples include the indicator light on the “caps lock” key of a keyboard to the signals on traffic lights. They’re also used successfully for automotive lighting, particularly brake lights.
Healthcare
Once mercury in fluorescent lighting became a concern, LED lighting became the ideal alternative for lighting in hospitals and healthcare facilities. The safety, longevity, and cost-effectiveness make LED lighting beneficial for healthcare. LED lighting also provides a more natural light, which not only helps with diagnostics but also patient comfort while in a hospital or doctor’s office.
Commercial Lighting
Office and retail spaces are among the most prominent LED lighting applications. These lights are chosen for their cost-effectiveness and luminosity, which helps employees see better and avoid eye strain and fatigue. The wide range of colors for LED lighting is also beneficial for influencing moods or highlighting products.
Street Lighting
Along with indicator lighting, LEDs are used for street lights to replace incandescent or fluorescent bulbs. LEDs are more cost-effective than their predecessors and last longer before replacement, cutting back on spending and maintenance for the city or municipality. LED lights are also effective for illuminating road conditions and keeping drivers safe.
Security Lighting
LED lighting is perfect for security lighting. The light is bright, and LED lights can be equipped with features like timers and motion sensors to deter criminal activities. LED security lighting is used both in residential and commercial applications.
Premium Lighting
With its versatility, LED lighting can be used in a variety of high-end products in a way that incandescent lighting cannot. LED bulbs and optics can be used in premium flashlights to create bright, intense illumination extending farther and longer.
LED lighting offers virtually limitless design opportunities for ultramodern luxury and premium lighting fixtures.2 Before LEDs, lighting fixtures had to be large and bulky to accommodate big bulbs and tubes. LED lighting boasts compact sizes with light optimization, giving consumers attractive lighting fixtures without compromising brightness and visibility.
Optical Design and LED Lighting at Apollo Optical Systems
Have an LED lighting and optics project? Apollo Optical Systems custom designs optics and optical components for LED lighting for aviation, medical, automotive, and architectural use. We also offer substrate-guided components and beam shaping. Contact us today to discuss your custom optics project!
Sources:
[1] https://www.energy.gov/energysaver/lighting-choices-save-you-money#:~:text=LEDs%20use%20up%20to%2090,longer%20than%20traditional%20incandescent%20bulbs. [2] https://www.freedoniagroup.com/Content/Blog/2018/06/28/The-Pros–Cons-of-LED-Integrated-Lighting-Fixtures
