The key difference between critical angle and acceptance angle is that we measure the critical angle within the fiber while we measure the acceptance angle outside the fiber.
An optical fiber a thin, flexible fiber with a glass core through which light signals can be sent with very little loss of strength. The terms critical angle and acceptance angle come under the reflection of light through an optical fiber.
CONTENTS
1. Overview and Key Difference
2. What is Critical Angle
3. What is Acceptance Angle
4. Side by Side Comparison – Critical Angle vs Acceptance Angle in Tabular Form
5. Summary
What is Critical Angle?
The critical angle is the angle of incidence beyond which rays of light passing through a denser medium to the surface of a less dense medium are no longer refracted but totally reflected. With respect to optical fibers, the critical angle is the least angle of incidence at which total internal reflection takes place.
Figure 01: Critical Angle to Prevent Light from Reflecting Back
Furthermore, if a light ray exceeds the critical angle, the light is totally reflected back to the direction where it came (into the denser medium).
What is Acceptance Angle?
Acceptance angle is the maximum angle within which an element accepts light. In an optical fiber, it is the maximum angle from the axis at which light can remain confined within the core for “total internal reflection.
Figure 02: Acceptance Cones
Furthermore, mathematically, acceptance angle is half of the angle of the acceptance cone; the light that enters the optical fiber will propagate only through a cone that we call the acceptance cone.
What is the Difference Between Critical Angle and Acceptance Angle?
The terms critical angle and acceptance angle come under the reflection of light through optical fibers. However, there is a difference between critical angle and acceptance angle. We measure the critical angle within the fiber, whereas we measure the acceptance angle outside the fiber.
Summary – Critical Angle vs Acceptance Angle
Basically, we come across the terms critical angle and acceptance angle when we study the reflection of light through optical fibers. However, the key difference between critical angle and acceptance angle is that we measure the critical angle within the fiber and the acceptance angle outside the fiber.
Image Courtesy:
1. “RefractionReflextion” By Josell7 – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Acceptance Angle-Optical Imperfections” By Jcc2011 at English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia