Objective of the Experiment

Grasp the concepts of transverse and longitudinal modes in lasers.

Learn to use the cat's eye coupler to observe laser transverse modes.

Learn to use a scanning interferometer to observe laser longitudinal modes, and master the calculation of longitudinal mode spacing.

Experimental Content

Learn to adjust the transverse mode of the output laser by using a cat's-eye sleeve with a semi-external cavity HeNe laser and observe through a light screen.

Learn to observe the output laser's longitudinal modes through an oscilloscope using an interferometer, and master the calculation of the longitudinal mode spacing.