Vergence Flashcards
Vergence
Quantitative measure of the degree of convergence or divergence of light at a particular position
Inversely proportional to the distance from the wavefront to the center of curvature
How is vergence measured ?
Measured by the curvature of the wavefront of light
What is curvature of a sphere?
Reciprocal of the radius
1/d
Unit of vergence
Diopters
-influenced by media
Vergence calculation
D = n/r
See photo
The linear distance used to calculate diopters is always in ________
Meters
Real objects
- give off diverging light
Real objects
- give off diverging light
Convergence
Occurs when light travels from a large area to a point of focus
Becomes stronger as it approaches the point of focus
NOTE: noo naturally converging rays exist
Condensing lens
Needed to converge light to a point focus at a predetermined distance
Real images
Are formed by converging light
Convergence sign convention
All converging light has a (+) sign convention
Distance r
Measured from the wavefront to the center of curvature
NOT always measured from the optical system
When distance from wavefront is same as light (+)
When distance from wavefront is opposite direction of light (-)
Curvature vs vergence
The longer the radius of curvature the water the di optic strength
The shorter the radius of curvature the stronger the diaoptic strength
Optical infinity
20 ft = 6 m and beyond
- here vergence is so weak that you can approximate to be 0 ( D = 1/-6 = -.17 =0 )
