Holmarc's Kerr effect apparatus (Model No: HO-ED-P-05A) is used to determine the Kerr constant of the Liquid (Nitro Benzene C6 H5 NO2 ). In this apparatus, Nitrobenzene is used as the Kerr agent because Nitrobenzene shows a large Kerr constant than other polar liquids. Multiple travel of laser beams through Kerr cell helps to make it compact. This apparatus helps students to acquire knowledge on the fundamental physical property, Kerr Effect.
The Kerr effect, also called the quadratic electro-optic effect (QEO effect), is a change in the refractive index of a material in response to an applied electric field.
By plotting the square of the applied voltage versus the phase shift between normal and extraordinary beam it is to be shown that the relation between the two quantities is approximately linear. From the slope of the straight line the Kerr Constant is to be calculated.
The phase-shift between the normal and the extra-ordinary light beam is to be recorded for different voltages applied to the Kerr cell respectively for different electric field strengths. The half wave voltage is to be determined.
Fig: Experimental Arrangement for Kerr Effect Apparatus
In this apparatus, polarized light from a DPSS laser is directed to pass through the space between the electrodes of the Kerr cell. The beam is reflected by a mirror from the other side of the Kerr cell and again it passes through the space between the electrodes. With the help of a beamsplitter and convex lens, the beam is directed to focus on a Si photo diode detector. Embodiments of Kerr effect apparatus provide a phase-shift between the normal and the extra-ordinary light beam and it can be recorded for different voltages applied to the Kerr cell for different electric field strengths.
Relative luminous intensity Vs Applied Voltage
Phase Shift Vs Voltage2