1. Silicone lens
a. Because silica gel has high temperature resistance, it is often used to directly package LED light-emitting devices.
b. Generally, the size of silica gel lens is small, with a diameter of 3-10mm.
2. PMMA lens
a. Optical grade PMMA (polymethyl methacrylate, commonly known as acrylic).
b. Plastic materials, advantages: high production efficiency (can be completed by injection molding and extrusion); high light transmittance (about 93% when the thickness is 3mm); disadvantages: the temperature cannot exceed 80° (heat distortion temperature 92 degrees) ).
3.PC lens
a. Optical grade Polycarbonate (PC) polycarbonate. Plastic materials.
b. Advantages: high production efficiency (can be completed by injection molding and extrusion); light transmittance is slightly lower (the transmittance is about 89% when the thickness is 3mm); disadvantages: the temperature cannot exceed 110° (the heat distortion temperature is 135 degrees).
4. Glass lens
Optical glass material, advantages: rich optical parameter characteristics, high light transmittance (97% transmittance at 3mm thickness), high temperature resistance, etc.; disadvantages: large volume and heavy weight, single shape, fragile, difficult to achieve mass production , Low production efficiency, high cost, etc. However, the current high price of such production equipment makes it difficult to popularize in the short term. In addition, the shortcomings of glass that are more fragile than PMMA and PC materials require more research and exploration. In terms of the improved technology that can be achieved now, the non-fragile characteristics of glass can only be improved by coating or tempering, although these treatments , The light transmittance of the glass lens will be reduced, but it will still be far greater than the light transmittance of ordinary optical plastic lenses. Therefore, the prospect of glass lenses will be broader.
