A new, to our knowledge, method of modifying methylene blue dichromated-gelatin (MBDCG) holograms by use of ninhydrin and removal of their amino groups and carboxyl groups, which strongly adsorb humidity, has been developed. The modified MBDCG holograms are stable for 1000-line/mm gratings (diffractional efficiency of 95%) in a high-humidity environment (relative humidity of 80%–85%). The modifying reaction does not affect the diffraction efficiency of the MBDCG holograms. It is demonstrated that the amino groups and carboxyl groups of the side chains in the gelatin do not undergo the chelation reaction with Cr iii in the sensitive area.
© 1998 Optical Society of America
Original Manuscript: August 7, 1997
Revised Manuscript: August 7, 1997
Published: January 10, 1998
Ketai Wang, Lurong Guo, Jianhua Zhu, Weiping Zhang, and Bo Cheng, "Methylene blue dichromated-gelatin holograms: antihumidity method for taking off strongly adsorbing humidity groups," Appl. Opt. 37, 326-328 (1998)