Benefits of LED technology
LED or Light Emitting Diodes have potentially replaced the traditional lighting source for its cost and size advantages. It was initially used as indicator lamps in a number of electronic devices. However, continuous development in LED technology had led to embrace this technology in all types of general lighting.
LEDs are extremely energy-efficient and can consume up to 90% less power than conventional fluorescent bulbs. As such they help to massively cut power costs. Because of low power usage, LEDs are becoming popular light sources in remote areas that use solar panels. LEDs also have long life of up to 60,000 hours compared to 1,500 hours for luminous bulbs. Moreover, they are durable and can withstand shock, vibration and extreme temperature. You can also improve safety by using LED since they produce 3.4 btu’s per hour compared to 85 for incandescent bulbs.
People are using LEDs in a variety of applications, including residential lighting, aerospace, architectural lighting, automotive, aviation, broadcasting, electronic instrumentation, entertainment and gaming, and more.
Especially in the micro-projection system, use of LED optics will increase over the years. It is because lighting uniformity and efficiency on spatial light modulators or SLM are two most important factors to gauge performance of micro-projection system. People often use tapered light pipe (TLP) and square compound parabolic concentrator (SCPC) as a beam shaper in LED-based micro projection system. By this, you will get SLM with uniform and efficient illumination.
However, TLP or SCPC has some disadvantages the primary one been insufficient compactness induced by the working length of TLP or SCPC for the illumination system. To overcome this problem, one can use TIR or Total Internal Reflection lenses.
Definition of TIR lens
TIR or Total Internal Reflection lenses are cone-like lenses that usually have rotationally symmetrical designs to distribute light in a rounded pattern. You can use TIR lens to collimated light or to generate a preferred uniform illumination.
TIR lens manufacturing process
During TIR lens manufacturing, often the designers do not pay attention to color uniformity, which also limits their application. You can however address this problem through effective color mixing, and use a phosphor-converted white LED module integrated with a compact modified free form to get compact size and high angular color uniformity (ACU).
Manufacturers design total internal reflection lens with an optimization method to combine and transfer most of the light emitted from LED optics into a rectangular target plane or RTP representing SLM. Typically, TIR lens has six surfaces controlled by seventeen dimensional parameters. Design takes place optimizing dimensional parameters with general algorithms. In order to keep RTP in immovable position with pleasing illumination uniformity and efficiency, designers consider illumination uniformity and efficiency on RTP during the optimization process.
In the Tracepro program, the simulation result of LED illumination system with the optimized TIR lens shows that the illumination efficiency and uniformity has achieved 61.9%, 76% with considering the limitation angle of light (15 degrees).
You can manufacture these lenses for multiple LED applications. Manufacturing of different sizes of TIR lenses depends on its optical performance, so one cannot specify FWHM angles, etc.