Optics 101

What is a Diffraction Grating?

Topics Covered

Introduction
Working Principle
Construction
Applications
References

Introduction

Diffraction gratings can be used to separate light of different wavelengths with a high resolution. A diffraction grating is a multiple slit arrangement made by etching lines on a transparent flat piece of material. These lines separate an incident beam of light with high resolution by following principles of diffraction.

Each of the lines are opaque; the gap in between the lines transmits light. The type of diffraction that is brought about by a diffraction grating with multiple slits is called Fraunhofer diffraction. This datasheet will look into the working principle, construction and applications of diffraction gratings.

Working Principle

A parallel beam of light is incident on the grating, by following Huygen’s Principle each of the transparent slits of the grating become a light source and spread out from each other. These sources interfere with each other, when constructive interference occurs light is made brighter at that point.

Construction

A diffraction grating consists of a flat piece of transparent material on which lines have been etched having uniform gaps in between. These lines are etched by photolithographic techniques and digital planar holography.

The striated muscles present in the human body are a form of natural gratings.

Applications

Some of the typical applications of diffraction gratings are as below:

  • Atomic spectra measurement
  • Optical spectrometers, monochromators and wavelength multiplexing devices.

References

 

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