optical glasses
|
This site provides you with the information about optical glasses, buy cheap brand name optical glasses online, optical glasses shopping tips, new style optical glasses pictures, price comparasion, buy discount optical glasses online, optical glasses shopping, buy lowest price new model optical glasses online, paypal payment, compare price, purchase brand name this year model optical glasses pictures, purchase cheapest factory direct optical glasses, warranty period, return policy, free delivery, fast delivery, next day delivery, how to buy good quality wholesale optical glasses, how to shop optical glasses, kids optical glasses photo, optical glasses purchase guide online, optical glasses purchase advice, how to take care of optical glasses, and more.
The most common types of glasses used in optics are crown glasses and flint glasses, designations based on their dispersions. Flint glasses contain lead. These designations are further subdivided by composition and have letter designations and number designations called "glass numbers".
Common crown glasses have indices of refraction around 1.5-1.6, while extra dense flint glass may have an index as high as 1.75 . Lenses of crown and flint glasses are often used in multi-component lenses because of their complementary properties. For example, a strong positive crown lens with its low dispersion may be used in a doublet with a weaker negative lens of flint glass (high dispersion) to correct for chromatic aberration.
The design of multi-component lenses requires very exacting specifications for the glasses used. Professional optics books have detailed tables of glasses with their glass numbers, densities, softening temperatures, etc.
|
