ABBE Value Interpretation

April 4, 2008 in Optical Spectrum by Scott

Different lenses have different properties. The density varies, known as index of refraction, and the ABBE VALUES are different for the various materials. The ABBE VALUE is a number given to describe the amount of chromatic aberration of an ophthalmic lens material. Here is a list of ABBE VALUES. The higher the number, the less amount of aberration.

MATERIAL INDEX ABBE VALUE
Crown Glass 1.523 59
High Index Glass 1.60 42
High Index Glass 1.70 39
Plastic CR-39 1.49 58
Mid Index Plastic 1.54 47
Mid Index Plastic 1.56 36
High Index Plastic 1.60 36
High Index Plastic 1.66 32
Trivex 1.53 43
Polycarbonate 1.58 30

Chromatic aberration is when white light is broken up into component colors. A color fringe may be noted around a light source or around an object. In reality, most patients never complain of color fringes but rather complain of blurriness and peripheral distortion. Note that crown glass has the highest ABBE number (least aberration) and polycarbonate has the lowest ABBE number (most aberration). The higher index of refraction means a denser material and therefore a thinner lens. Cosmetically, thin lenses appear more attractive but has more aberration. They also cost more. High index glass has more aberration than standard crown glass. Different manufacturers may have a different ABBE VALUE for the same exact lens. You might have experienced a previous pair of eyeglasses provided better vision when you thought there were no changes in prescription nor type of lens material with your new pair. Polycarbonate lenses are used extensively for safety eyewear such as in your shooting glasses and has the most aberration. Keep in mind that most of us see just as well with a low ABBE VALUE lens as compared to a high ABBE VALUE lens. Crown glass is most commonly used for eyeglass lenses with an index of refraction of 1.523. There are however, 50 glass formulations used today for various optical applications, all with its unique properties. Ernst Abbe was a brilliant German mathematician and physicist. Carl Zeiss was so impressed with Ernst Abbe that he was hired by Zeiss in 1866 and later became the owner of the company.