VilasPrieto, José LuisSánchez Brea, Luis MiguelBernabeu Martínez, Eusebio2023-06-192023-06-192013-10-131. X. Zhang, “Optimal achromatic wave retarders using two birefringent wave plates: comment,” Appl. Opt. 52, 7078–7080 (2013). 2. J. L. Vilas, L. M. Sanchez-Brea, and E. Bernabeu, “Optimal achromatic wave retarders using two birefringent wave plates,” Appl. Opt. 52, 1892–1896 (2013). 3. H. Hurwitz and R. C. Jones, “A new calculus for the treatment of optical systems. II. Proof of three general equivalence theorems,” J. Opt. Soc. Am. 31, 493–495 (1941). 4. Saha, K. Bhattacharya, and A. K. Chakraborty, “Achromatic quarter-wave plate using crystalline quartz,” Appl. Opt. 51, 1976–1980 (2012). 5. G. Kang, Q. Tan, X. Wang, and G. Jin, “Achromatic phase retarder applied to MWIR & LWIR dual-band,” Opt. Express 18, 1695–1703 (2010).1559-128X10.1364/AO.52.007081https://hdl.handle.net/20.500.14352/33594© 2013 Optical Society of America.This reply attempts to cast some more light on the achromatic systems composed by wave plates, in particular to the calculus of the overall retardation and the use of the Jones matrix equivalence theorem. An equivalent expression for the overall retardation of the system in terms of the trace is also givenengjournal articlehttp://dx.doi.org/10.1364/AO.52.007081http://www.opticsinfobase.orgopen access535OpticsÓptica (Física)2209.19 Óptica Física