Application of Norland adhesive for holographic recording

Norland UV-adhesive NOA68 was studied as a material for holographic optical elements fabrication. Permanent transmission diffractive gratings were inscribed by the exposure to the interference field of UV Ar-ion laser. The contributions of the volume and the surface parts of the phase modulation to the efficiency of the gratings were investigated for different gratings periods. The depth of the surface relief grows up to 250 nm with an increase in the grating period. For relatively small periods ⩽2.5 μm the contribution of the surface relief part to the total diffraction efficiency is negligible and gratings can be considered as volume diffractive structures. The deep (up to 1.5 μm) surface relief with almost square profile was manufactured by the UV exposure through a mask. Both techniques do not require any subsequent wet or thermal developing process. The mechanism of the holographic image formation is discussed.