Impact of an initial laser beam profile on the structure and correctability of thermal blooming aberrations

Prior thermal blooming studies focused on macroscopic phenomena, often lacking quantitative analysis of the wavefront aberration structure. This paper uses Zernike polynomial decomposition to compare the thermal blooming aberration structures and correctability of Gaussian versus flat-top beams. Under the weak thermal blooming assumption, the study reveals that the initial intensity gradient dictates the aberration structure. Flat-top beam thermal blooming is 'pure-type' and tilt-dominant; Gaussian beam blooming is 'complex-type' with significant multi-mode coupling. At N_D = 50, this discrepancy yields max Strehl Ratios (SR) of 0.54 (flat-top) and 0.22 (Gaussian) for low-order correction. This supports a beam-shaping strategy to 'reshape aberrations at the source, simplifying correction'. The demonstrated 'structural stability' and 'predictable severity' provide tools for 'optimal correction' via aberration balancing and open pathways for open-loop predictive correction.