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Announcements 3/28/12. Prayer Exam review problems for sign-up. Calvin & Hobbes. Reading Quiz. A lens placed after a diffraction aperture causes the Fraunhofer pattern to be produced: before the focal length at the focal length after the focal length (but at a finite distance) at infinity.
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Announcements 3/28/12 • Prayer • Exam review problems for sign-up Calvin & Hobbes
Reading Quiz • A lens placed after a diffraction aperture causes the Fraunhofer pattern to be produced: • before the focal length • at the focal length • after the focal length (but at a finite distance) • at infinity
f f f f Lenses • What it object is not at infinity? • What appears at q? • What appears at f? Object at f: “Fourier transform plane”
Lens Fourier Transforms at focus of lens From Hecht
“Fourier Transform smoothing” Before After From Hecht
Reading Quiz • What does the “Rayleigh criterion” tell us? • The angle at which both light polarizations have equal reflection coefficients • The angle at which p-polarized light has minimum reflection • The angular separation resolvable by an imaging system • The number of orders produced by a diffraction grating
Reading Quiz • The Rayleigh criterion for resolving two point light sources comes from: • Fourier transforms of delta functions. • Jinc functions’ maxima and minima. • Lagrange multipliers. • Parallax of stars.
What do you get in this situation? board with hole • What if there’s a lens in the hole? • What if there isn’t a board? • What if you have two light sources? superimposed patterns at focus pattern at infinity pattern at focus f
Rayleigh Criterion Curve is (J1(x)/x)2 plotted vs (krb/f), = qD/l (using sinq q) Mathematica “FindRoot” command: q/l = 1.21967… (= first zero of J1(x)) Rayleigh Criterion