What are the common lens materials for eyeglasses?

Natural Crystal Lenses
The main component of this material is silicon dioxide, typically available in colorless and brown variants. It is resistant to abrasion and has a small coefficient of thermal expansion. However, due to its unique transparency to ultraviolet light, it can cause eye fatigue when worn for extended periods. Additionally, crystal lenses often contain impurities due to uneven density, which can lead to birefringence.

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• Glass Lenses
  Common materials include "Toric lenses," "Crox lenses," "Crox-Si lenses," "Ultraslim lenses," and "1.60 glass lenses." Glass lenses are more scratch-resistant than other materials, but they tend to be heavier. Their refractive index is relatively high: regular lenses have a refractive index of 1.523, and ultra-thin lenses can reach up to 1.72, with some going as high as 2.0. Glass lenses are thinner than resin lenses for the same prescription due to their higher refractive index. They have excellent light transmission and stable mechanical and chemical properties. Clear lenses are called optical white lenses, while colored lenses, like pink lenses, are known as Crox-Si lenses. These can absorb ultraviolet rays and slightly reduce the effect of strong light. However, glass lenses are fragile and heavy.

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• Resin Lenses (CR-39)
  The most representative resin lens is CR-39, made from a hard and transparent material with a refractive index of 1.499 and a light transmission rate of 92%. It has good thermal stability, remaining stable below 150°C. It is resistant to water, corrosion (except for strong acids), and most organic solvents. It is lighter than glass, with a specific gravity of 1.32, which is half that of glass. Resin lenses are impact-resistant, not easily broken, and offer enhanced safety (complying with FDA standards). They are comfortable to wear and easy to process, making them suitable for various frames, including semi-rimless and rimless designs. However, resin lenses are more prone to scratches and are thicker (1.2-1.3 times) than glass lenses for the same prescription due to their lower refractive index.

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• PC Lenses (Polycarbonate Lenses)
  Polycarbonate lenses, also known as "space lenses" or "cosmic lenses," are made from thermoplastic material. This means they are solid before heating and will shape into lenses once heated. However, they can deform if overheated, making them unsuitable for high-humidity or high-temperature environments. PC lenses are highly durable, impact-resistant (can be used in bulletproof glass), and extremely lightweight, with a specific gravity of just 2 grams per cubic centimeter. Despite their excellent impact resistance, PC lenses are prone to scratches, have poor heat stability, and soften at temperatures above 100°C.

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• Nylon Lenses
  Nylon lenses primarily use TROGAMID, a special transparent polyamide (commonly known as memory nylon). This is an ultra-fine anti-UV crystal material that does not scatter visible light. The most significant advantage of nylon lenses is their excellent stress crack resistance and outstanding chemical resistance. They also have better processing capabilities than PC lenses, making them the preferred choice for high-end lenses. While they are coated to improve scratch resistance, their surface still offers less protection than CR39 lenses and is comparable to PC lenses. The relatively high cost of nylon lenses is a barrier to their widespread use.

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• Polarized Lenses (Polaroid Lenses)
  The main function of polarized lenses is to filter light coming from one direction while blocking light from other directions, similar to how Venetian blinds filter light. This helps eliminate glare, especially from surfaces like water, land, or snow. Polarized lenses increase contrast, reduce eye strain, and provide clearer, more natural vision. They are particularly popular with drivers as they reduce glare from the sun and other reflective surfaces. Polarized lenses also block UV rays and harmful light, which helps prevent cataracts and eye fatigue. With enhanced scratch resistance, polarized lenses provide high durability and excellent impact resistance, protecting your eyes from harm.

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At Hechang, we are dedicated to offering the highest quality products across a wide range of materials to meet your specific needs. Whether you are looking for durable, lightweight, or innovative materials, we ensure that our products deliver exceptional performance and longevity. From premium lenses to custom-made solutions, we offer an extensive selection to cater to various industries and applications.

Explore our diverse collection of products, crafted from the finest materials including crystal, glass, resin, polycarbonate, and more. With Hechang, you can trust that each product is designed to provide superior functionality, durability, and style.