Experts glasses frame, lens purchase tips

Natural materials:

Most commonly used crystals, is made up of quartz mine to figure out themselves. Main components are silica (SiO2), in pure Crystal containing apt-SiO2.

Category:

Rock: SiO2 has a high purity. Brown: due to the presence of other elements, and different colors, can reduce the transmittance of visible light, comfortable wearing Cheap Ray Ban Sunglasses allow homophobia, and foster said.

Advantages: material hardness, easy to wear.

Disadvantages: caot completely absorb UV. Material density, uneven stripe and bubble appear containing impurities, causing birefringence phenomena, thereby affecting vision.

Glass:

Suitable for the production of lenses of glass is glass, particularly strict quality requirements.

Such as refractive index, dispersion and transmission, etc. Main component silica (SiO2), followed by boron dioxide (B2O3) and phosphorus pent oxide (P2O5).

Advantages: good hardness, not worse than Crystal. Mixed with various oxides can be colored, you can reduce the glare can also absorb ultraviolet, infrared and other harmful rays (thus making optical glass lenses have a 300-year history).

Disadvantages: heavy weight, weight is resin material 1 time. As the refractive index increases, the proportion of marked increase, resulting in wears uncomfortable.
Poor impact resistance, mechanical damage can easily cause the glasses to hurt. It is less secure, people in the past century has been looking for a better alteative.

Resins:

Main components are organic, dominated by carbon, hydrogen, nitrogen, and oxygen. Resin for the production of Ray Bans Outlet lenses must be homogeneous, transparent and no distortion. Types currently used are as follows:

Poly methyl mentholated

Brand name: PUMA, also known as Alex.

Advantages: light weight, glass one-second.

Disadvantages: it is a thermoplastic material, solubility in 75C, heat deformation, and cause changes in diapers. Inadequate surface hardness, wear less.

Propylene carbonate acetate, also known as ally propels glycol acid grease, brand name: Colombia resins, for oil extract.

Advantages: light weight, safety, good impact resistance, UV-resistant, fully blocking the 350mm ultraviolet light.

Disadvantages: poor wear resistance, lower refractive index make lenses look thick.

PC (Polycarbonate), polycarbonate, is made of aliphatic carbonate around the song and Phenylalanine an ABS is not easily fixed. Lenses made with such materials are called "space".

Advantages: light, 57% lighter than traditional glass, security glass,
Its impact resistance is 60 times, bullet-proof glass thickness 2.5cm can do.

Thin, CR-39 Ray Ban Sunglasses with refractive index 1.6 equal to the thickness of the lens.