Postulates of Ray Optics (1-1) @vashahri-en

Uploaded May 2022 | Updated September 2026, 3 hours ago

In the first lecture of Fundamentals of Photonics, we review the postulates of ray optics. In particular, we learn about the #Fermat'sPrinciple and #Hero'sPrinciple.

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Fundamentals of #Photonics, by Saleh and Teich, 3rd ed.

$How light curves: Graded index materials explained (1-7) This video explores Graded Index (GRIN) materials, focusing on how light behaves in media where the refractive index varies with position. We begin with a review of Fermat’s Principle and the concept of the Optical Path Length, setting the stage for understanding light trajectories in inhomogeneous media. Key topics covered include: The Ray Equation: Deriving the mathematical foundation for light propagation using the variational method. Paraxial Approximation: Simplifying complex 3D equations for practical solutions in optical systems. Trajectory Analysis: Solving for light paths in specific scenarios, such as slabs with parabolic index profiles. Optical Fibers: Examining how GRIN profiles lead to harmonic, self-focusing trajectories like meridional and helical paths. Whether youre a physics student or an optics enthusiast, this lesson provides a deep dive into why light curves and how we can mathematically predict its path through complex materials. References: Principles of Optics by Born and Wolf (7th Edition), Appendix 1. #Physics #Optics #Photonics #GradedIndex #RayOptics #Electromagnetics$ $Spherical boundaries and lenses (1-5) This detailed video on spherical boundaries and lenses provides a rigorous walkthrough of fundamental optics principles, complete with mathematical derivations and practical applications. What you will learn: Spherical Refraction: A step-by-step derivation of the refraction equation at a single spherical boundary using Snells Law and the paraxial approximation. The Famous Equation: How to derive and use $n_1/z_1 + n_2/z_2 = (n_2-n_1)/R$ for calculating object and image positions. Conjugate Planes & Magnification: Understanding the relationship between object and image planes, including lateral magnification and image inversion. Lens Maker’s Formula: Applying spherical boundary principles twice to derive the focal length equation for thin lenses. Practical Applications: An overview of LED collimators that combine reflection and refraction, plus a look at spherical aberrations and the caustic curve. Timestamps: 0:00 - Introduction to Spherical Boundaries 1:12 - Deriving the Refraction Equation (Snells Law) 2:14 - Paraxial Approximation 3:58 - Defining Object and Image Distances ($z_1$, $z_2$) 5:06 - The Spherical Boundary Equation 6:32 - Conjugate Planes and Magnification 8:28 - Introduction to Aberration 8:45 - Case Study: LED Collimators 9:35 - Spherical Lenses & Thin Lens Approximation 10:21 - Lens Makers Formula 11:50 - The Thin Lens Equation 12:51 - Non-Paraxial Rays and Caustic Curves If youre studying university-level physics or photonics, this lecture serves as a foundational guide to understanding how light interacts with curved surfaces. Subscribe for more Physics and Photonics lectures!$ $Light guides and optical fibers (1-6) In this lesson, we explore how light can be guided from one point to another, focusing on the fascinating principles behind modern optical fibers. We’ll demonstrate how to effectively bend light and discuss why total internal reflection is the ideal mechanism for minimizing power loss compared to traditional lenses and mirrors. In this video, you will learn: The fundamental differences between guiding light with lenses, mirrors, and fibers. The structure of optical fibers: Core vs. Cladding and the role of refractive indices ($n_1$ and $n_2$). How to calculate the critical angle ($theta_c$) using Snells Law for light confinement. Defining the Acceptance Angle ($theta_a$) and calculating the Numerical Aperture ($NA$). Whether youre a physics student or a photonics enthusiast, understanding these concepts is key to mastering how data and energy are transmitted across the globe through light. #Physics #Photonics #OpticalFiber #Optics #TotalInternalReflection #ScienceEducation #LightGuides$