Diode pumped Nd:YAG laser with active Q-switching and mode locking for hole drilling

A diode-pumped Nd:YAG laser operating with active-passive Q-switch mode locking, has been developed. The acousto-optic repetition train was one kilohertz with generated pulse train widths 65 ns, single pulse widths 200 ps and an average power of 6.5 W. Improvement of efficiency of small diameter deep holes laser drilling in different materials was studied.     

Principles of laser drilling with adapted control over the parameters of repeated laser pulses

Principles of laser drilling of deep holes with adapted control over the parameters of the multipulse laser irradiation are determined. In good agreement with earlier experimental results, the possibilities for increasing the depth and productivity of the laser treatment of deep cavities via controlled modulation of the Q-factor and active synchronization of the modes of a high-power single-mode YAG:Nd laser are substantiated theoretically.     

A method for controlling the phase locking of a multichannel laser system

The conditions leading to control over phase-locked oscillation in a set of three loop lasers containing self-pumped phase-conjugate gain-grating mirrors by using a LiF: F ₂ ^? passive Q-switch are studied both experimentally and theoretically. Cases of spatially uniform lamp pumping and high-efficiency spatially nonuniform transverse diode pumping are considered.     

Basic types of discontinuity in circular acoustic wave guide

It is considered the interaction of acoustic waves with two basic discontinuities--"diameter step" and "diaphragm with coaxial opening"--in a cylindrical acoustic waveguide with a rigid wall. The problem is considered and solved in rigorous formulation for the case of axial symmetry and below first radial resonance (f(r1)) in the waveguide. Obtained data demonstrate that a one-dimensional (1-D) model provides good results for the "diameter step" if the frequency does not exceed 18%-50% of f(r1). Calculated data for the "diameter step" demonstrate that this discontinuity follows the reciprocity principle (below f(r1))--the parameter of nonreciprocity does not exceed calculation errors. Data for the "diaphragm" demonstrate good agreement with the Lamb formula for a rigid screen with parallel slots--a 2-D problem in the Cartesian coordinates. Calculation errors for the both discontinuities were evaluated with the energy conservation law. The difference between sum of power fluxes in reflected and transmitted waves and the power flux in the incident wave does not exceed 1%.