Anti-Reflective Lenses Flashcards
Which is a correct statement concerning light waves that are more than 20 feet for their source?
a.) They lose their magnetic property but retain their electrical property
b.) They become polarized and are propagated only in one direction
c.) They are propagated as concentric circles
d.) They have a flat wave front
d.) They have a flat wave front
What is the range of visible wavelengths the human eye is sensitive to?
380nm to 760nm
Which of the following occurs to the greatest degree when light encounters a lens surface?
a.) Changed to heat energy
b.) Reflected
c.) Absorbed
d.) Transmitted
d.) Transmitted
Lens reflections increase in brightness and intensity as _____
a.) The refractive index of the lens’ material becomes higher
b.) The front base curve of the lens steepens
c.) The thickness of the lens increases
d.) The angle of reflection decreases
a.) The refractive index of the lens’ material becomes higher
How much light does a 1.74 index lens reflect?
14.1%
On what optical characteristic are AR treatments based upon?
Destructive interference
What does the term broadband mean in regard to AR treatments?
A reduction of surface reflections over the entire visible spectrum
Which type of glare does AR treatment eliminate?
Distracting glare
Where is ultra-violet found in the electro-magnetic spectrum?
Above violet
When light is reflected back towards the wearer it can do what?
Compromise vision and reduce visual performance
Who is credited with being the inventor of AR treatment?
Carl Zeiss Company
In order for an AR lens treatment to be effective, its index of refraction must be ___ of the index of the material it is being coated upon
The square root
How thick are today’s modern AR lens treatments?
0.2-0.3 microns
What coating material was used to create early AR lenses?
Magnesium fluoride
Each layer of a modern AR treatment is composed of a different material of either ____
Silicon dioxide or a metal oxide
How do modern AR lenses prevent crazing of the AR treatment on plastic lenses?
A special hard coating is used that acts as a transition between the glass-like AR treatment and the plastic lens
What are the names of the methods that are used to place a hard coating on a plastic lens?
Spinning and dipping
How thick is the hard coating used on plastic lenses?
3 to 5 microns
A rainbow-like visual effect that can occur when an AR treatment is not properly index matched to the lens material it is coating upon is known as what?
Newton’s Fringes