THERMAL LENSING MEASUREMENT OF A THERMAL LENS COMPENSATION HIGH POWER LASER OBJECTIVE

摘要

An effort was under taken to mitigate thermal lensing and have an easy and compact means of monitoring thermal lensing in a high power laser system. Utilizing the negative temperature coefficient of refractive index in CaF_2 with the nearly opposing positive temperature coefficient of refractive index in SiO_2, a multi-element focusing objective was fabricated to reduce the amount of thermal lensing experienced with a multi-kilowatt, cw fiber laser. In addition, an all-passive optical design beam analyzer was developed to accurately measure the focus shift of an all SiO_2 lens objective in contrast to the CaF_2/SiO_2 multi-element lens to compare their perspective thermal lensing values.