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Intro to Opt Test #2

Refractive Errors, Focal Length, Prisms, etc

What is a prism? A non-parallel sided medium.
Prisms bend light towards the...? Base
Prisms deviate images towards the...? Apex
What are prism diopters? Units used to measure the power of a prism.
What is nearsighted vision, when the eyes are too strong, referred to as? Myopia
What is myopia corrected with? Minus lenses
What is farsighted vision, when the eyes are too weak, referred to as? Hyperopia
What is used to correct hyperopia? Plus lenses
What is astigmatism? Eye has different powers in each meridian.
What is a meridian? Line through the center of a circle.
Do steeper, shorter curves create weaker or stronger power? Stronger (Remember SSS - steeper, shorter, stronger)
What is a toric surface? A surface that is not spherical?
What lenses are used to correct astigmatism? Cylinder or compound lenses
What has a toric surface on the front? Plus cylinder lens
What has a toric surface on the back? Minus cylinder lens
What has a toric surface on front and back Bitoric lens
What is presbyopia? Loss of accommodation as you age.
What lenses are used to correct presbyopia? Plus lenses
What is the steepest curve on a toric surface? Toric Cross Curve
What is the flattest curve on a toric surface? Toric Base Curve
What are the Toric Cross Curve and Toric Base Curve referred to as? Major Meridians
The major meridians are how many degrees apart? 90 degrees
The major meridians create what is known as the...? Toric cross
Convex surfaces have what kind of curves? Plus curves
Concave surfaces have what kind of curve? Minus curves
What is optical infinity? 20 ft
What is the optical center? The point of no prism because the front and back surfaces are parallel where vision is the sharpest.
Where is the optical center on a plus lens? The thickest part
Where is the optical center on a minus lens? The thinnest part
What is the optical axis? The imaginary lines through the optical center of a lens perpendicular to the front and back surfaces.
The further the object point is from the lens, the ______ the image point is to the lens? Closer
Rays of light coming from 20ft or beyond can be considered....? Parallel
What is the focal point? Image point when the object is at infinity.
What is the focal length of the lens? Image distance from the lens to the image point when the object is at infinity.
Images formed by minus lenses are....? Imaginary
What is conjugate foci? A specified object point taken together with it's specific image point, that share the property of reversibility.
Older biconvex and biconcave lenses are known as...? Flats
Lenses common today where only one side is concave or convex are known as....? Bents
What is another word for "bents"? Meniscus
What is the mechanical center? The actual physical center of the lens, which can be different that the optical center.
Concave mirrors magnify images how? Make them bigger
Convex mirrors magnify images how? Make them smaller
When dealing with mirrors the angle of reflection will always equal what? The angle of incidence
What is the image point? The point to which the lens focuses light.
What is the distance between the two major meridians? Interval of sturum
Formula for diopters in meters D=1/f
Formula for diopters in inches D=40/f
Prism formula Prism=deviation(cm)/distance(m)
Created by: griffiskr