In an optical head device, a birefringence correcting element 5a containing a material showing mono-axial refractive index anisotropy is located before an objective lens. In accordance with the invention, in order to provide incentive for the player to keep playing the machines and to add additional excitement, non-jackpot awards are paid out to players of the linked gaming machines based on triggering thresholds met by each jackpot. The composition has good performance and has good adhesion to a wide range of substrates including non-porous and semi-porous materials as well as porous materials.