An “adaptive cooling method” for wavefront preserving mirrors

Abstract In this work, a cooling mechanism is proposed that can achieve adaptive adjustment to match the spatial thermal load distribution. Segmented copper blocks are adopted to realize discrete adjustments of effective cooling length according to the footprint variations of specific wavelengths; Holes are applied on the cooling blocks to further control the local cooling efficiency achieving local thermal shape adjustment; The coolant flow rate is also switchable to increase system adjustability and fault tolerance. This method can provide high accuracy shape optimization of optics thermal profile with a height error lower than 1nm RMS, and a slope error below 30nrad RMS, under the thermal load of 100kHz high repetition rate for the entire wavelength range of 1-3nm.