Laser beam stability control based on differential compensation system

Abstract

This paper proposes a differential compensation system with a differential optical path which is consisted of a pentaprism, a half-pentaprism and a beam splitter. This system can split the source laser beam into two equal and opposite laser beams without considering the thickness of the beam splitter. Thus the average of the positions of the two laser beams remains constant despite the laser beam dithering angle. Simulations verify the feasibility of this system in ideal situation. Furthermore, the compensation error is analyzed taking into account the thickness of the beam splitter. Theoretical analysis shows that the system error is within 6 μm. Monte Carlo simulation are then verified that the collimated laser beam dithering can be reduced within 7 μm considering the machining error of the parameters of the prisms and the system error. This system with advantages of compact structure, free from electro magnetic interference(EMI) and transplantation, is wildly used in one dimensional measurement fields especially for the compact and containment detecting setup.