Some defintionsNeutralizing (front vertex) power: Incident vergence on front of lens that yields image at infinityBack Vertex Power: Emergent vergence from back surface of lens for object at infinity. They exist in thin lenses, but all coincide with the axial position of the lens. Practical applications of thick lenses and schematic eyesAccommodation and AC/A ratioCatoptric imagesĬardinal PointsIn thick lenses, not valid to assume that focal lengths are measured from the center of lensConvenient reference positions for all optical systemsPrincipal planesPrincipal pointsNodal points Lateral Mag of Lens SystemsSo, if you have the following lenses8x7x2xTotal mag is (8)(7)(2) =112X Lens systems: Size and OrientationProduct of Lateral Magnification of each object/image Note that you cannot predict orientation of final images Where is the final image?Knowns F1=+15D, F2=-3D, t=17cm, obj dist l1=-1m,Unknown image dist lEquations L=F+L, L=n/l and L=n/l

An object is placed 1m in front of the first lens. ProblemLens system has 2 thin lenses, +15D and -3D with CT of 17cm.

The Effect of Thickness on PowerWhen thickness is 0, the F=F1+F2If both surfaces are the same sign, increasing the thickness makes the net equivalent power more negativeIf one is negative and one is positive, then increasing CT makes the lens more negative. If the n1=n3, then f=fIn English, this means that the focal lengths on either side of the lens will be the same if the index of refraction is the same on both sides of the lens. Imaging of multiple lens systems- element by elementRORIn1n2n3VOROE1E2E3 The medium between the elements is the index of the lens system Use the image of one lens as the object of the next lensEach refracting surface is an element of the system. Thick Lens Theory Element by Element ImagingUse previously developed thin lens imaging techniques for each refracting surface. Thick Lens TheoryA lens is not thin if the CT is sufficient to change the powerThe eye is a moderately complex thick lens system Focusing power depends on curved surfaces, each separated by media of different indices of refraction What well do todayThick lens theor圜onceptsCardinal points explainedSchematic eyesExactReducedConstruction of retinal imagesĬatoptric imagesAngle KappaAccommodation and AC/A ratio

System lens theory