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Dive into the principles of mirrors and lenses, understand image formation, mirror equations, and the thin lens concept. Quiz and exam preparation included. Practice with concave and convex mirror calculations. Learn the lensmaker's equation and graphical methods for optical systems analysis. Enhance your understanding of geometric optics in this comprehensive guide.
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Geometrical Optics – Part II Chapter 24
Stuff • We continue with mirrors and lenses and even refractive surfaces. • Quiz on Friday • For a while, office hours will be in, of all places, my office. We really don’t need MAP-318 except before exams. And the hours are too confusing. • Next Exam is on Wednesday, December 2nd. • I give up on the remaining evil clickers. Clicker grade=0. • Let’s move on.
R When the Center of Curvature is on the same side of the outgoing ray, R is positive. Otherwise, if the center of curvature is not on the same side as the outgoing ray, R is negative.
Concave Mirror/Paraxial Approximation Consequently MIRROR EQUATION Mirror, mirror on the wall…
Image Formation ‘ ‘ y’<0 (from the diagram) so image is inverted.
A concave spherical mirror has a radius of 10 cm. Calculate the location and size of an 8mm object a distance 15 cm from the mirror. 10 cm 5 cm Normal to mirror and bounces back along incoming path.
A concave spherical mirror has a radius of 10 cm. Calculate the location and size of an 8mm object a distance 10 cm from the mirror. 10 cm 5 cm
A concave spherical mirror has a radius of 10 cm. Calculate the location and size of an 8mm object a distance 2.5 cm from the mirror. virtual image 10 cm 5 cm eye
The Concave Mirror The Equations are the same as the convex mirror but the Radius of the mirror is negative
Spherical Refractive Surfaces air glass
The Thin Lens • We ignore the thickness of the lens. • We will use mostly geometrical methods. • Any ray that bends is assumed to bend only once at the center of the lens.
From whence it came Surface 2 Surface 1 n>1 n=1 n=1.5 n=1 Surface 2
The thin lens - geometry parallel
More Geometry • Lens is thin • Actual thickness of the lens is ignored. • Image from first surface provides the object for the second surface. • Paraxial Ray Approximation • sin(x)=tan(x)=x • cos(x)=1 • x is in RADIANS
More Geometry Triangle PQO and triangle P’Q’O are similar. We willshow that for a very thin lens: F1=F2=f The Thin Lens Equation
This, of course depends on where the object is placed with respect to f.
Image that would form if material “a” was all on this side of the lens. Object for second surface. Thin Lens (con’t)
Procedure for equation • Solve for image position for first surface • Use image as object for the second surface. • Use the refraction equation in both cases. For a lens. na=nc=1 So we can call the middle one just n Mess with the algebra and you will get:
FINALLY – with some algebra and obvious substitutions, we get: The Lensmaker’s Equation Ta Daaa!
Two Ways to do this STUFF • Algebraically using the lens equation (with the 1/f if you know it) • Using graphical Methods
Most important case: converging lens So, now you know!