The influence of phase difference on the effect of multi-beam interference processing

Abstract

The influence of phase difference in laser interference lithography system is often ignored by researchers. In this paper, we simulated the interference process of dual-beam, three-beam and four-beam, and the influence of phase difference on the interference effect was discussed in detail. The simulation results show that in the process of dual-beam and three-beam interference, the change of phase difference causes the shift of the interference pattern but does not change the laser intensity distribution of the interference field, and has no effect on the actual interference processing; while in the process of four-beam interference, the change of phase difference can change the laser intensity of the interference field. Based on this, we built a four-beam interference processing system with dual-channel mutual injection solid-state laser as the laser source to process aluminum materials. The phase of the beam is changed by adjusting the optical path of the output laser, and the interference processing effect is observed when there are different phase differences between the beams. The experimental results show that in the process of four-beam interference processing, when the phase difference between beams is not zero, the interference processing will be greatly affected, and the processing results will appear some phenomena, such as small depth of concave holes, irregular shape, unclear boundary between concave holes and so on.