Comment on "Development of a 10.8-eV tabletop femtosecond laser with tunable polarization for high-resolution ARPES" [Rev. Sci. Instrum. 96, 093004 (2025)].

With this Comment, we bring to the attention of the scientific community that, to the best of our knowledge, no circularly polarized third harmonics in gases can be generated by starting from a circularly polarized fundamental beam. Hence, the evidences reported in the paper by Gao et al. [Rev. Sci. Instrum. 96, 093004 (2025)] should arise from complementary effects, or, if proved, they definitely need extensive explanation and discussion.