Design of the Quasi-Optical Transmission Line for Millimeter Wave Deep Drilling

A 45GHz quasi-optical transmission line with three quasioptical mirrors for millimeter wave deep drilling is designed and experimental tested. Based on the technique of Gaussian beam transformation, the proposed optical transmission line, which consists of three mirrors, is investigated and optimized by vector analysis of the fields on mirror surfaces. The synthesis method has been verified to transfer the electromagnetic wave from the MOU to the specified position of the sample to be heat. The numerical results show that the power transmission efficiency is over 95%. The experimental results demonstrate the output pattern at the position of rock is a good agreement with the desired fundamental Gaussian mode and the output power density of 1.65 $kW/cm^{2}$ at the heated rock surface meets the preliminary requirements to melt the rock.