Total internal reflection: Theory and applications (1-4) @vashahri-en

Uploaded June 2022 | Updated September 2026, 3 hours ago

This video explores the behavior of light at planar boundaries, focusing on the fundamental principles and practical applications of Total Internal Reflection (TIR).

We begin by applying Snell’s Law to differentiate between external and internal refraction. You will learn how to derive the critical angle ($\theta_c$)—the specific point where light begins to reflect entirely rather than passing through a boundary—and understand why a surface acts like a perfect mirror beyond this limit.

The lecture also covers essential optical components used in laboratory settings, including:

Beam Splitters: How they divide or combine light rays using partially reflective surfaces.

Prisms: A deep dive into deviation angles, including a step-by-step mathematical derivation of the relationship between incident angles and exiting rays.
Advanced Beam Directors: An introduction to biprisms, Fresnel biprisms, and axicons (cone-shaped devices) for controlling light symmetry.
This session is part of our ongoing series on Physics and Photonics, designed for students and researchers looking to master ray optics and experimental setups.

Key Topics: 0:00 External vs. Internal Refraction 1:12 The Critical Angle ($\theta_c$) Derivation 2:20 Total Internal Reflection (TIR) Explained 3:05 Beam Splitters and Glass Plates 3:50 Prisms and Deviation Angles 5:00 Mathematical Proof of Prism Relations 8:45 Applying Snell's Law to Multi-Boundary Systems 11:08 Biprisms and Axicons

$Total internal reflection: Theory and applications (1-4) This video explores the behavior of light at planar boundaries, focusing on the fundamental principles and practical applications of Total Internal Reflection (TIR). We begin by applying Snell’s Law to differentiate between external and internal refraction. You will learn how to derive the critical angle ($theta_c$)—the specific point where light begins to reflect entirely rather than passing through a boundary—and understand why a surface acts like a perfect mirror beyond this limit. The lecture also covers essential optical components used in laboratory settings, including: Beam Splitters: How they divide or combine light rays using partially reflective surfaces. Prisms: A deep dive into deviation angles, including a step-by-step mathematical derivation of the relationship between incident angles and exiting rays. Advanced Beam Directors: An introduction to biprisms, Fresnel biprisms, and axicons (cone-shaped devices) for controlling light symmetry. This session is part of our ongoing series on Physics and Photonics, designed for students and researchers looking to master ray optics and experimental setups. Key Topics: 0:00 External vs. Internal Refraction 1:12 The Critical Angle ($theta_c$) Derivation 2:20 Total Internal Reflection (TIR) Explained 3:05 Beam Splitters and Glass Plates 3:50 Prisms and Deviation Angles 5:00 Mathematical Proof of Prism Relations 8:45 Applying Snells Law to Multi-Boundary Systems 11:08 Biprisms and Axicons$

$Reflection, refraction, Snells law, and the proof of Snells law (1-2)$

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