Classifications of Lenses

What is basic lens?

The lens is made according to the law of refraction of LED light. A lens is an optical component made of a transparent substance such as glass, crystal, or the like. The lens is a refractor whose refractive surface is two spherical surfaces (part of the spherical surface), or a spherical surface (part of the spherical surface) of a flat transparent body. 

It has a real image and a virtual image. Lenses can generally be divided into two broad categories: convex lenses and concave lenses. The central part is thicker than the edge part, which is called a convex lens, which has three kinds of convex, convex, convex and concave; the central part is thinner than the edge part, which is called concave lens, flat concave, convex and concave.

LED lenses are generally silicone lenses, because silicone is resistant to high temperatures (and can also be reflowed), so it is usually packaged directly on the LED chip. Generally, silicone lenses are small in size and have a diameter of 3-10 mm. And the LED lens is generally closely associated with the LED, which helps to improve the light-emitting efficiency of the LED, and the optical system LED lens that changes the light field distribution of the LED, that is, closely associated with the LED, helps to improve the light-emitting efficiency of the LED, An optical system that changes the light field distribution of an LED. 

The high-power LED lens/reflector is mainly used for collecting and guiding light of high-power LED cold light source products. The high-power LED lens designs the light distribution curve according to the angle of the different LEDs, and increases the optical reflection to reduce the light loss and improve the LED flood light efficiency (and the set aspherical optical lens). The following focuses on the secondary concentrating high power LED lens of PMMA material.

a), classified by material

1, silicone lens

a. Because silicone is resistant to high temperatures (and can also be reflowed), it is usually packaged directly on the LED chip.

b. The general silicone lens is small in volume and has a diameter of 3-10 mm.

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, extrusion); high transmittance (93% penetration rate at 3mm thickness); disadvantages: temperature can not exceed 80 ° (heat deformation temperature 92 degrees ).

3, PC lens

a, optical grade material Polycarbonate (referred to as PC) polycarbonate.

b. Plastic materials, advantages: high production efficiency (can be completed by injection molding, extrusion); light transmittance is slightly lower (the penetration rate is about 89% at 3mm thickness); disadvantage: the temperature cannot exceed 110° (heat distortion temperature 135) degree).

4, glass lens

Optical glass material, advantages: high transmittance (97% penetration at 3mm thickness), high temperature resistance, etc. Disadvantages: large volume, heavy weight, single shape, fragile, difficult to achieve mass production, low production efficiency, cost higher. However, the current price of such production equipment is high and it is difficult to popularize in the short term. In addition, the disadvantages of glass compared to PMMA and PC materials are more fragile, and more research and exploration are needed. In the improved process that can be realized now, the non-fragile properties of the glass can only be improved by coating or tempering treatment, although after these treatments The transmittance of the glass lens will be reduced, but it will still be much larger than that of the ordinary optical plastic lens. So the prospect of glass lenses will be even broader.

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