• K Ranganathan

Articles written in Pramana – Journal of Physics

• An alternative method to specify the degree of resonator stability

We present an alternative method to specify the stability of real stable resonators. We introduce the degree of optical stability or the 𝑆 parameter, which specify the stability of resonators in a numerical scale ranging from 0 to 100%. The value of zero corresponds to marginally stable resonator and $S &lt; 0$ corresponds to unstable resonator. Also, three definitions of the S parameter are provided: in terms of $A&amp;D$, $B&amp;Z_{\text{R0}}$ and $g_{1}g_{2}$. It may be noticed from the present formalism that the maximum degree of stability with $S = 1$ automatically corresponds to $g_{1}g_{2} = 1/2$. We also describe the method to measure the 𝑆 parameter from the output beam characteristics and 𝐵 parameter. A possible correlation between the 𝑆 parameter and the misalignment tolerance is also discussed.

• Thermal birefringence-compensated linear intracavity frequency doubled Nd:YAG rod laser with 73 ns pulse duration and 160Wgreen output power

In a thermally birefringence-compensated linear cavity configuration, ∼160 W of average green power by intracavity frequency doubling of AO Q-switched Nd:YAG/LBO-based laser is demonstrated. The corresponding optical to optical conversion efficiency is estimated to be ∼12.7%. The pulse repetition rate is 20 kHz with the individual pulse duration of 73 ns. The beam quality parameter is measured to be 18.

• Laser shock peening of steam turbine blade for enhanced service life

Fretting-fatigue is an important factor influencing service life of turbine blades. The present paper describes laser shock peening of potential crack nucleation site in the root region of steam turbine blade for its enhanced service life. The experimental study, performed with an in-house developed 2.5 J/7 ns Nd:YAG laser demonstrated that laser peening introduced a residual surface compressive stress of −260 to −390 MPa. Case depth of laser peened surface layer was found to be more than 900 𝜇m.

• # Pramana – Journal of Physics

Current Issue
Volume 93 | Issue 6
December 2019

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019