(redirected from Polycarbonates)
Also found in: Dictionary, Encyclopedia.


(pŏl″ē-kăr′bĭ-nāt, -nĭt) [″ + ″]
A transparent polymer used to manufacture eye protectors, shields, and other medical devices.
Medical Dictionary, © 2009 Farlex and Partners


A very strong type of plastic often used in safety glasses, sport glasses, and children's eyeglasses. Polycarbonate lenses have approximately 50 times the impact resistance of glass lenses.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

index of refraction

The ratio of the speed of light in a vacuum or in air, c, to the speed of light in a given medium, v. Symbol: n. Hence,
n = c/v
The speed of light in a given medium depends upon its wavelength. Consequently, the index of refraction varies accordingly, being greater for short wavelengths (blue) than for longer wavelengths (red). The index of refraction forms the basis of Snell's law, which quantitatively determines the deviation of light rays traversing a surface separating two media of different refractive indices. Syn. refractive index. Plural: indices. See dispersion; law of refraction; gradient-index lens; high index lens; speed of light; refractometer.
Table I3 Refractive indices of some transparent media at selected wavelengths
spectral lineGFDCA
wavelength (nm)430.8486.1589.3656.3759.4
aqueous or vitreous humour1.34401.34041.33601.33411.3317
crystalline lens1.43071.42591.42001.41751.4144
spectacle crown1.53481.52931.52301.52041.5163
dense flint1.63971.62901.61701.61221.6062

Table I4 Index of refraction n of various media for sodium light (λ = 589.3)
water (at 20ºC)1.333
spectacle crown glass1.523
flint glass (dense)1.62
flint glass (extra dense)1.65-1.70
titanium oxide glass1.701
calcite crystal
ordinary ray1.658
extraordinary ray1.486
quartz crystal
ordinary ray1.544
extraordinary ray1.553
Canada balsam1.53-1.54
silicone rubber1.44
hydrogel polymer
20% water content1.46-1.48
75% water content1.37-1.38
aqueous humour1.336
crystalline lens (average effect)1.42
vitreous humour1.336


Various organic or synthetic materials (e.g. CR-39, HEMA, polymethyl methacrylate, polycarbonate, etc.) that can be transformed into solid shapes to make spectacle frames, contact lenses, ophthalmic lenses, etc. and can be made to have good optical surfaces, high light transmission and refractive indices and dispersions similar to that of crown or flint glass. See acetone; index of refraction; plastic spectacle frame.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
* Makroblend[R] EL4000 polycarbonate/polybutylene terephthalate (PC+PBT): MD&M West marks the debut of this new grade of polycarbonate blend, which offers a high level of chemical resistance against many of the powerful disinfectants used to wipe down hospital room surfaces and equipment today.
Several polycarbonate and PC-based blends were introduced by the Polymers Div.
Line is compatible with a wide variety of thermoplastic polyurethanes (TPUs), nylon, polycarbonate and ABS.
These pigments neither affect nor are affected by the usual polymerization catalysts or exotherms and are generally recommended for acrylics, both casting syrups and molding powders, nylons, polycarbonates, epoxies, urethanes, polyesters, PE, PP, both plastisol and extrusion vinyl, ABS, and PS.
According to the company, the Luwax line is compatible with a wide variety of thermoplastic polyurethanes (TPUs), nylon, polycarbonate and ABS.
Rohm & Haas says Paraloid EXL-5137 is targeted for use with ABS, polycarbonate and polycarbonate/ABS blends.
Both Weston 619 and Ultranox 626 have broad regulatory approval in polypropylene, polyethylene, PVC and polycarbonate for food packaging applications.
Mo Liu, Director of China polycarbonates at Covestro, said: "Covestro polycarbonate is widely used in medical applications, and we have partnered with Wego in many medical devices including dialysers and oxygenators.
Covestro is a leading global supplier of polycarbonates and has comprehensive expertise in their processing and application.