ISO 489 Test Standard Explained

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Refractive Index - ISO 489

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Refractive index, or index of refraction, is the ratio of the velocity of light in a vacuum to its velocity in the material in question. Refractive index is useful for identifying materials, and is important in optical applications.
Testing for ISO 489 is performed using one of two test methods as described below.

Refractive Index Testing Methods
Method	Name	Description
A	Refractometric Method	Measurements are made using an Abbe refractometer. This method is recommended when high accuracy is required.
B	Immersion Method	Measurements are made using a microscope by utilizing the Becke line phenomenon. Accuracy is similar to that of Method A.

Index of refraction can be calculated using Snell's Law:
n₁ / n₂ = sin θ₂ / sin θ₁
where n₁ and n₂ are the refractive indices of mediums 1 and 2, θ₁ is the angle of incidence, and θ₂ is the angle of refraction.

Refractive Index Geometry

Similar Standards

ASTM D542

Property information for specific grades of resin are available in the Prospector.
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