PHY 452/562 Lasers and Modern Optics
Transcript of PHY 452/562 Lasers and Modern Optics
Prof. Eden Figueroa
Lecture 3: Laser beam propagation
PHY 452/562 Lasers and Modern Optics
Sept 4th 2013
Geometrical optics refresher ABCD matrix analysis Back to paraxial wave equation. Gaussian beam solution.
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Discussion: How can we describe the propagation of a laser beam in a complicated experiment?
Geometrical optics
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Geometrical OpticsLight is treated as rays. Although not physical it yields intuitive results.
Law of reflection (Snell’s law)
2211 sinsin nn
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Ray tracing through thin lenses
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We will describe the rays at any propagation distance z by using:
r: position from optical axisθ: the angle that the ray makes with the optical axis.
The angle is positive if the ray should be rotated clockwise to coincide with with the +z direction.
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Paraxial ApproximationWe will assume that the angle is small and the ray is close to the optical axis.
The input and output parameters are related through a lineartransformation:
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Ray matrices (ABCD matrices)For many optical components, we can define 2 x 2 ray matrices.The effect on a ray is found by multiplying its ray vector.
Ray matrices can describe very complex systems.
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(Homework problem)
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For cascaded elements, we simply multiply ray matrices.
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