What Is the Angle by Which a Prism Bends a Laser Beam?

The angle by which a beam of laser light is bent when it travels through a prism depends on the properties of the glass and the angle at which the laser light strikes it.

Types

The speed of light in a vacuum is a fundamental constant of the universe and does not change. The speed of light in a vacuum divided by the speed of light in a different medium like glass is called the index of refraction.

Features

When the beam of light strikes the glass surface of the prism, the angle of the light beam is measured relative to an imaginary line extending out from the glass and perpendicular to the surface of the glass. This imaginary line is called the normal.

Function

The angle by which a beam of light is bent when it travels through the boundary between two media---from air into a prism of glass, for example---is given by Snell's Law, n1 sin O1 = n2 sin O2. In this equation, n1 is the index of refraction in the first medium, n2 is the index of refraction in the second medium, O1 is the angle from the normal at which the laser light strikes the glass, and n2 is the angle from the normal in the glass. When the beam of light exits the prism, it is refracted again as it passes across the boundary between the two media, and once again the angle is given by Snell's Law.

References

• "Physics for Scientists and Engineers"; Richard Wolfson and Jay Pasachoff; 1999
• Georgia State University Hyperphysics: Prisms