Thick lens and multiple lens system Flashcards
What is the cardinal point method
Combine elements or surfaces into unique system by redefining reference plans and power
Involves more calculation in setting up new system
Redefining the reference points
What is the elemenbt by element imaging
Uses single refracting surface and thing lens imaging formula for each element or surface
Image through each element or surface seperatly
Locate first surface image, use as object for second surface and continues for rest of elements
What are the 6 cardinal points
- primary and secondary focal point
-primary and secondary principal point
- primary and secondary nodal point
What is the primary focal point of the thick lens power
The object posistion that yields image at infinity and is measures from primary principle plane to primary focal point
What is the secondary focal point
image plane when object is at infinity
measures from secondary principal plane to secondary focal point
What is the front focal length (ffl)
distance from front surface of lens or first element of optical system to the primary focal point of the system
What is the back focal length (bbl)
distance from back surface of lens or last element of optical system to secondary focal point of the system
What is the optical center (O)
The position where refracted ray from the front surface crosses the optical axis
Optical center is independent of refractive index and wavelength
What does nodal points represent (N)
Apparent position of the optical center when viewed from front and back of lens
What does nodal points represent
Apparent position of the optical center when viewed from front and back of lens
What are principal planes (H)
primary principle plane: where all incident rays strike
secondary principle plane: where all emerging rays are refracted from
What is the effect of thickness on principal planes
In thin lens, principlpe planes coincide and pall at center of lens
As thickness increaesm principal palnes seperate H falls to left of H’ and both fall within lens
When thickness increases further, planes coincide and reverse order
What is the effect of thickness on power
Zero lens thickness, power=sum of two powers
Increase in thickness= increase in negative power and decrease in posistive
What is neuralizing power
The incident vergence on front surface of lens or first element of optical system that tield final image at infinity
What is back vertx power
The emergent vergence from back surface of lens or last element at optical system for object placed at infinite position
