Wavelength properties of DCG holograms under the conditions of different temperature and humidity

摘要

Holograms recorded in dichromated gelatin (DCG) are usually sealed with a glass plate cemented with an epoxy glue to protect the holograms from moisture in the environment. An investigation of the wavelength properties of sealed DCG holograms had been carried out paying attention to holograms which were exposed to different temperature and humidity environment in this work. The investigation had revealed that (a) exposing the sealed DCG holograms to high relative humidity (RH=98%) environment or immersing them in room-temperature water for 20 hours can not affect the holograms; (b) the sealed DCG holograms can be used at temperature below 50 °C without showing undue detrimental effects regarding their optical properties; (c) the peak wavelength of sealed DCG holograms can cause blue shift of several nanometers at 70°C～85°C and the velocity of blue shift is proportional to the environmental temperature; (d) the holograms can be destroyed at 100°C or above. The experimental results above will be analyzed and discussed in this paper. A method to improve the stability of sealed DCG holograms is proposed: baking the sealed DCG holograms at proper temperature (e.g., 85 °C in this study).