Home Optics Experiments PE-0900 Diffraction Grating

Keywords:

  •  Grating Constant
  •  Amplitude Grating
  • Phase Grating
  • Reflection Grating
  • Transmission Grating
  • Spectral Resolution
  • Diffraction Order

 

Basic experiment

Intended institutions and users:

Physics Laboratory

Engineering department

Electronic department

Biophotonics department

Physics education in Medicine

 

Introduction

How it works ...

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PE-0900 Diffraction Grating

Educational PE-0900 Diffraction Grating Kit

Joseph von Fraunhofer, the investigator of the solar lines, invented the diffraction grating in 1821. This optical element showed a much higher dispersion than any glass prism and allowed Fraunhofer to investigate the solar spectrum in a resolution much better than ever seen before.

Enormous quality improvement as well as optimization of the manufacturing technique of ruled gratings are the results of Henry Rowlands efforts in development of diffraction gratings. His gratings were used worldwide and were unbeaten in quality and resolution for decades. Nowadays holographic techniques using the interference of laser beams allow manufacturing gratings with larger grating constants and bigger size.

The experiment comprises transmission gratings of different grating constants (lines per cm) a green laser with known wavelength of 532 nm and an energy saver lamp emitting a variety of different spectral lines. The resulting interference pattern is imaged on a white screen with mm scale. Applying gratings with different parameter the resolution power is demonstrated. By using a mesh like two-dimensional grating impressive patterns of light spots are created and the analogy to the principles of x-ray diffraction on crystal lattices or atomic layers demonstrated.

PE-0900 Diffraction Grating

PE-0900 Diffraction Grating how it works

The emitted radiation of the light source illuminates the adjustable slit. The image of the slit is projected by means of the imaging lens to the image screen which is fixed to the goniometer arm. After passing the grating the incident light is divided into multiple orders and the spectral distribution becomes visible as vertical bars (line), the image of the slit. The intensity of the image on the screen depends on the adjusted width of the slit. Closely neighboured lines may merge if the width of the slit is too wide. At this point the resolution comes into consideration and other gratings (1) with different grating constants are applied.

PE-0900 Diffraction Grating

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