Polarisation Characteristics of a Laser Beam From HeNe Source-Physics-Lab Report, Exercises of Physics

Download Polarisation Characteristics of a Laser Beam From HeNe Source-Physics-Lab Report and more Exercises Physics in PDF only on Docsity! Polarisation characteristics of a laser beam from HeNe source Four types of polarisation may be investigated in this experiment. Unpolarised laser beam Or unpolarised light from conventional sources e.g. tube lights, sun light etc. Linearly Polarised light Circularly polarised light and Elliptically polarised light You will be provided the following equipment: Two linear polarisers, Two quarter wave plates, two laser sources, one photo –detector, three mounts along with holders out of which two are fitted with angular rotational stages. Fig. 1 Holes in the optical bench A typical mount A typical holder docsity.com First align your laser source according to the set up shown in Fig. 1. All your mounts and holders must also be aligned, i.e. the centre of the holders must be at the level that the needle should just approach their centre points. Fig. 2 To check that the given laser source is un-polarised, put a linear polariser in the path of the laser beam and a detector at the other end. Rotate the polariser by say 5 degrees in steps up to a 360 and record the intensity obtained from the photo-detector. A volt meter is connected for this purpose to the photo detector. Plot a graph between the intensity versus the angle of rotation of the polariser. Remove the polariser and record the laser intensity directly with the photo detector. What do you conclude about the intensity of the beam with polariser and without polariser? Fig. 3 Photo Detector B Notch indicating polarisation axis Linear Polariser /4 plate Holes in the optical bench Photo Detector B A typical mount Rotatable Linear Polariser holder docsity.com