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The Synthetic Aperture Focusing Technique (SAFT) is employed in laser ultrasonic non-destructive testing to image defects. However, during the laser ultrasonic imaging process, the influence of multi-mode waves often introduces various artifacts in the imaging results. We investigated a multi-iteration frequency-domain SAFT (MIF-SAFT) algorithm to tackle this challenge. Initially, a single low-precision F-SAFT imaging result is performed to identify potential defect locations. Subsequently, a back-projection method is applied to determine defect positions and separates acoustic waves of different modes in the B-scan. After that, a multi-mode F-SAFT imaging is performed for evaluation, and the above process is repeated until the imaging outcome stabilizes. The result shows that artifacts are removed when the image remains unchanged after multiple iterations, and the imaging quality is effectively improved by MIF-SAFT. Furthermore, including directivity patterns of laser ultrasound also enhances defect imaging capabilities within MIF-SAFT. Additionally, we examined the MIF-SAFT's capacity to detect multiple defects, which can image them simultaneously. • Multi-iteration in F-SAFT for artifact removal. • Different ultrasonic signals are separated by using the algorithm. • Directivity patterns are performed to enhance the imaging result. • Applied for multiple defects imaging simultaneously. [ABSTRACT FROM AUTHOR]