hey all
for an assignment at uni i need to write up about refractive index...any ideas on why it is important in optics??--other than makes lenses thinner?
thanks
leena
hey all
for an assignment at uni i need to write up about refractive index...any ideas on why it is important in optics??--other than makes lenses thinner?
thanks
leena
no longer playing in this sand box
Last edited by HarryChiling; 02-21-2007 at 04:55 AM.
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The refractive index has several applications and implications in spectacle lenses:
- As the refractive index of a lens material increases, the lens becomes thinner and lighter in weight since the curves are shallower.
- As the refractive index of a lens material increases, the Abbe value generally decreases, resulting in an increase in dispersion and a reduction in optical performance.
- If the refractive index is above 1.530, the material is considered a "high-index" material.
- As the refractive index of a lens material increases, the surface reflectance of the lens material also increases.
- The refractive index of a lens material varies across the entire visible spectrum, becoming highest in the blue end and lowest in the red end.
- The refractive index is important in lens surfacing for determining the effective power and precision of lap tools.
- The are two "reference index" values in use internationally, the Helium d line and the Mercury e line, and the measured focal value of a lens will depend upon the reference index.
- If there is a difference in refractive index between the scratch coating and the lens material, interference fringes may result.
- Layers of alternating refractive index are used to eliminate reflections in antireflection coatings.
Darryl J. Meister, ABOM
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