Why does PMMA have better transluency than PC in terms of optics for led work lamps

Reflector or optical len is very important for the brightness and lighting performance of led work lamps. Basically, two types of raw materials are used, such as PMMA (Polymethyl Methacrylate), which is also known as acrylic or Plexiglas and PC (Polycarbonate). Generally speaking, PMMA achieves about 5% better than PC materials in terms of light transmission and translucency.

Typically, PMMA has a higher light transmittance rate at about 92% in the visible spectrum. That is to say,more of the light produced by the led work lamp passes through the PMMA material with less internal absorption or scattering. On the other hand, PC usually has a slightly lower light transmittance at about 88%. For high power led work lights, this little difference can be noticeable in applications where maximum light output and focused clarify are desired. In poor weather or moisture environment,PMMA materials has lower haze values than PC materials. Less haze on the surface of optics ensures a clearer and more direct transmission of light, which is so important for optical performance of LED work lamps, especially in marine applications requiring focused beam or sharp light patterns.

Also, PMMA is well-known for its excellet optical clarity and resistance to yellowing over time because of UV exposure. Unless UV resitance treatment is made on PC optics, common PC materials can sometimes show a slight yellow tint, or may become yellowish over prolonged exposure to UV light. In contract, PMMA materials keep its colorless transparency better to ensure true color of LED illumination.

In theory, the refractive index of PMMA is about 1.49 while it is about 1.58 for that of PC materials. Less light is reflected at the surface of optics but more light is transmitted when the refractive index is relatively lower. The little difference in refactive index will result in totally higher light transmission.

It is hard to make a conclusion which material is best for optics of led work lamps depending on specific requirements. Although PMMA can achieve brighter,more energy-saving and color-accuracy illumination in many high power led lights application, it cannot work reliably at high temperature above 80 degrees celcisus. It is also much easier to scratch compared with pc material.