DIFFUSER & IT's TYPE

The traditional method of diffusing light is to position a frosted glass in front of the light source. But glass has a very high absorption-coefficient, which blocks a large amount of the LED light output. Apart from that, glass is heavy, increasing the weight of the whole product. It also does not possess the required toughness and is prone to breakage.

Nowadays, manufacturers are adopting new ways to develop cost-effective diffusers entirely from plastic.

LED diffusers generally come with two types of surface finishes—opal (milky) and frosted (translucent). The distribution of light through frosted diffusers is good but the LED light is quite visible. Opal diffusers give better results than frosted options—the light is more uniformly distributed and the LED is well concealed. LED diffusers are available in a variety of forms like UV-tolerant films and rigid sheets. Also, they are manufactured using various high quality plastic materials.

Polycarbonate (PC): 

This is a thermoplastic that has been customized for use in LED parts like reflectors, lenses and, most importantly, diffusers. PC components can be thinner and lighter than glass, and the material offers flexibility in design. Polycarbonate can be molded in the form of sheets and films which can be an excellent choice for diffusion of LED hot spots.

It is almost unbreakable, hence scoring over glass because of its high strength and elastic coefficient. It can resist extreme temperatures.

·    As it is more durable and impact-resistant, it has a longer life span making it cost-effective.

·       It provides a soft, diffused light.

·       It is very light and thin to handle during manufacturing.

·       Can be used to create complex shapes like curved light diffusers.

·       Available in UV stabilized grades for outdoor use.

Acrylic or polymethyl methacrylate (PMMA):

If you want a diffusion solution with fire-resistant properties, then polycarbonate is the best choice, but if you are looking for optical properties and the highest level of illuminance, acrylic or polymethyl methacrylate (PMMA) is the right choice. PMMA has superior optical properties compared to PC. It offers good light transmission and is easy to fabricate.

·       It has superior optical properties and illuminance.

·       It has the highest light transmission.

·       It is naturally UV stable, and this property can also be enhanced.

· It has excellent weather resistance and good high-temperature performance.

·       It provides design flexibility.

·       An acrylic plate has excellent weatherability and high surface gloss.

·       It is low cost and easy to mould.

Polystyrene :

Polystyrene (PS) is a naturally transparent thermoplastic. It is available in the form of solid plastic as well as rigid foam material. It is used in a variety of consumer products and light diffusion solutions. But this material is controversial as it is slow to biodegrade.

·       It is very low on cost.

·       It is wear resistant and scratch resistant.

·       Its chemical stability is good.

·       It has good surface anti-static properties to prevent dust adsorption.

·       It provides good optical transmittance and strong refraction.



When selecting thermoplastics for a light-diffusing cover or lens, transparency becomes a pivotal criterion. In its natural form, the polymer must be highly transparent to minimize the loss of LED output during the light diffusion process. While the number of appropriate engineering polymer solutions are by themselves limited, considering just cost, polycarbonate (PC) and acrylic (polymethyl methacrylate or PMMA) stand out.

Polycarbonate or acrylic

The choice between PC and PMMA is a close call as both are very similar in price, processing convenience and optical properties. The final choice depends on the application requirements. Table 1 compares the properties that manufacturers and developers should consider when selecting between the two polymers.

Prioritizing which properties are important for your application will make the selection process easier and more accurate for manufacturers and developers. Acrylic will be a good choice if optical properties are of high priority and the illuminance level (lux units) needs to be as high as possible as well. On the other hand, if the application requires fire resistance because of the high risk of fire, polycarbonate will be the only choice.



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