We made near infrared multicolor imaging observations of a disk around Herbig Be star HD100546 using Gemini/NICI .
K ( 2.2 \mu m ) , H _ { 2 } O ice ( 3.06 \mu m ) , and L ’ ( 3.8 \mu m ) disk images were obtained and we found the 3.1 \mu m absorption feature in the scattered light spectrum , likely due to water ice grains at the disk surface .
We compared the observed depth of the ice absorption feature with the disk model based on ( 13 ) including water ice photodesorption effect by stellar UV photons .
The observed absorption depth can be explained by the both disk models with/without photodesorption effect within the measurement accuracy , but slightly favors the model with photodesorption effects , implying that the UV photons play an important role on the survival/destruction of ice grains at the Herbig Ae/Be disk surface .
Further improvement on the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models .