Laser equipment for piercing holes with a diameter of 0.01–0.04 mm

Abstract

The application of laser radiation with ordered time and spatial structure, in particular, the transition to a pulsedperiodic laser effect, greatly widens the possibilities and increases the efficiency of laser treatment of metals. At the same time, the efficiency of pulsed laser radiation with a high power density (W > 10 W/cm) may be restricted by the formation of optical discharge plasma in air absorbing radiation. This circumstance greatly restricts the area of technological application of the most widely used Nd: YAG lasers operating in the Q-factor modulation regime. The situation greatly changes when metal and other materials are subjected to low-power laser pulses. A series of such pulses may be generated when several radiation pulses are formed during a single pumping pulse. This makes it possible to realise formation of effective erosion layers of plasma ensuring the displacement of the screening layer of air plasma from the zone of the effect, during the period separating consecutive radiation pulses. This is accompanied by increase of the depth, accuracy of dimensions and shape of the holes. The diagram of laser equipment for piercing holes with a diameter 0.01-0.4 mm is shown in Fig. 1. The master generator (MG) was represented by LTI-503 industrial laser with acousto-optical modulation of the Q-factor whose output power in the single-mode generation regime was 2 W. The repetition frequency of the pulses of the master generator was regulated in the range 3.8-50 kHz. In this case, the pulse time changed from 0.4 to 0.66 msec. Amplifier A was represented by the circuit for rotating the cross-section of the beam around optical axes ensuring the formation of beams of high optical quality. Focusing radiation on the component and examination of the enlarged image of the area of piercing the hole was provided by modernised industrial system SOK-1. The rapid selection of the area of deposition of the hole was carried out using focusing radiation of a He-Ne laser