ANSI Z80.3-2008 pdf download Nonprescription Sunglass and Fashion Eyewear Requirements
3 Definitions
3.1 Capable of withstanding an impact test: Capable of withstanding an impact test means able to withstand impact as determined by 100% testing or by testing of a statistically significant sample (for example, conforming to the requirements of ANSI/ASQC Z1.4-1993) of each production batch, or at the option of the manufacturer, as an integral part of the manufacturing process. Capability of withstanding an impact test is determined by testing at any feasible stage of manufacture, as described in 5.1.1 and 5.1.2.
3.2 Density: Density (also called optical density) is the logarithm to the base 10 of the reciprocal of transmitance (Density =log 1/t ). 3.3 Geometric center: The geometric center is the point midway between the two vertical tangents and midway between the two horizontal tangents of the edges of a lens.
3.4 Lens fracture: A lens is considered to have fractured when it cracks through its entire thickness and across a complete diameter into two or more separate pieces, or when any piece of lens material visible to the naked eye becomes detached from the ocular surface, or if the test ball passes through the lens.
.5 Lens types
3.5.1 Polarizing lens: A polarizing lens is a lens whose luminous transmitance varies with the amount and orientation of the polarization in the incident light.
3.5.2 Photosensitive lens: A photosensitive lens is a lens whose luminous transmitance or color, or both, depends on the recent exposure history of the lens.
3.5.3 Gradient density lens: A gradient density lens is a lens whose luminous transmittance varies significanty across the lens.
3.5.4 Uniform density lens: A uniform density lens is a lens whose luminous transmitance does not vary significantly over the area of the lens.
3.5.5 Strongly colored lens: A strongly colored lens is a lens that causes the apparent chromatcity of standard iluminant D65, when viewed through the lens, to fall outside of the boundary for daylight (4.6.3.1 part 4, and Figure 1).
3.6 Noncorrective impact-resistant lenses: Noncorrective impact-resistant lenses are glass lenses, plastic lenses, or laminated glass lenses made impact resistant by any method; however, all such lenses shall be capable of withstanding the impact test described in 5.1.
3.7 Production batch A production batch is an identifiable group of lenses of essentially the same curvature, thickness, and material, manufactured under essentially the same conditions and during a substantially continuous production period.
3.8 Refractive properties
3.8.1 Refractive power: Refractive power of a lens is measured in diopters and is the reciprocal of the back focal length expressed in meters.
3.8.2 Astigmatic power: Astigmatic power is a measure of the maximum refractive power difference between any two meridians within a lens.
3.8.3 Prismatic power: Prismatic power of a lens, expressed in prism diopters, is the apparent displacement, in centimeters, of an object located 1 m from the lens in the meridian of maximum displacement.
3.9 Transmittance properties
3.9.1 Luminous transmittance: Luminous transmittance is a function of the spectral transmittance of the lens weighted by the corresponding ordinates of the photopic luminous efficiency distribution of the CIE (1931) standard colorimetric observer and by the spectral intensity of standard iluminant C.