Hollow circular-truncated cone resonator and its hollow variable biconical laser beam

Jinglun Liu,Nianchun Sun,Qionghua Wang,Mei Chen

doi:10.1117/1.oe.53.5.056113

Abstract

To obtain a hollow variable biconical laser beam (HVBLB), a CO2 laser having a hollow circular-truncated cone resonator (HCTCR) is presented. This HCTCR comprises a rotationally symmetric total-reflecting concave mirror at the bottom, a rotationally symmetric part-reflecting convex mirror at the top, and a hollow circular-truncated cone discharge tube at the middle. The cross section of this generated biconical laser beam changes from annulus to circular to annulus and the size of this cross section from big to small to large as the propagation distance increases. So, a kind of laser beam with variable center intensity from zero to peak value to zero is obtained and is known as HVBLB. Due to the inclusion of part of the hollow laser beam (HLB) and solid laser beam, this HVBLB requires no additional beam-shaping element and has broad applications such as optical trapping and commercial manufacturing.

Highlights

Hollow laser beam (HLB) means there is a dark region of intensity in the central axis of a beam
An HLB obtained directly by a hollow cone-shaped resonator (HCR) CO2 laser has been proposed according to Ref. 7
The output mirror of the hollow circular-truncated cone resonator (HCTCR) will face lower power density due to the minimum spot lying outside the output mirror

Summary

Introduction

Hollow laser beam (HLB) means there is a dark region of intensity in the central axis of a beam. Among these methods, an HLB obtained directly by a hollow cone-shaped resonator (HCR) CO2 laser has been proposed according to Ref. 7. As minimum spot of the output beam is located in its surface, the output mirror of this HCR should support higher power density. The dark region of this HLB will become bigger as the transmission distance increases This HLB must depend on a focusing system for various applications. The output mirror of the hollow circular-truncated cone resonator (HCTCR) will face lower power density due to the minimum spot lying outside the output mirror

HCTCR and Its Hollow Variable Biconical Output Beams

Simulation and Discussion

Conclusions