To find out the wavelength of He-Ne laser using diffraction grating

Applied Physics

To find out the wavelength of He-Ne laser using diffraction grating. In short in this experiment of applied physics we are going to find out the wavelength of He-Ne laser by using diffraction grating method. This experiment is really simple and easy to understand and learn download below we had also attached a YouTube video for your betterment of understanding.

Experiment: Diffraction Grating

Aim: To find out the wavelength of He-Ne laser using diffracting grating.

Apparatus: Diffraction grating He-Ne laser source, Optical bench, Screen.

Objectives: To use diffraction grating for diffraction of laser.

Observation:

1) Total number of lines on diffraction grating N=15000 lines per inches.

2) Grating element formula

d= Width of the grating / Total number of lines ruled on grating.

Procedure:

1) Switch on the laser source and set laser spot on diffraction grating.

2) Place the screen at the suitable distance from diffraction grating, so that diffraction spot will appear on the screen. Also set the distance between source and the diffraction grating.

3) First order as well as second order diffraction spot will appear at the screen. Measure the distance of the spot on the screen from the centre.

4) Thus, follow the observation table and find out wavelength of the source used.

Important diffraction grating: