Spherical aberration compensation in Nd:YVO ₄ amplifiers

The thermally induced spherical aberration in an 878.6 nm pumped Nd:YVO 4 laser amplifier was compensated using a custom-designed optical plate shaped according to the Zernike polynomial for spherical aberration. Wavefront measurements performed with a Shack-Hartmann sensor were applied to a 976 nm probe beam, unaffected by amplification, and the 1064 nm signal beam. Identical wavefront distortions and an effective compensation by the compensation plates were observed in both cases, confirming that the aberration originates solely from thermal lensing. This validates the probe beam as a reliable diagnostic tool and demonstrates the effectiveness of the compensation plate in restoring wavefront quality.