| 摘要 |
PURPOSE:To offer an optical disk device where the recording of a signal is stably executed even when the wave length fluctuation of a light source exists. CONSTITUTION:The relation of the vitreous material and angle between a beam reshaping prism provided between the light source and an optical disk and a beam spritter is set as follows. The beam reshaping prism is constituted by a first prism 31 of a refractive index n1 and the beam spritter is by a second prism 32 of a refractive index n2 and a third prism 33 of a refractive index n3 which are stuck each other. The refractive index change of the respective prisms as against wave length change are d n1, d n2 and d n3, the refractive angle at the incident side end face of the first prism 31 is theta1, the incident angle is theta2 and the refractive angle is theta3 at the incident end face of the second prism 32 and the incident angle at the third prism 33 is theta4 so as to nearly satisfy the condition of d n1(sintheta2+costheta2.tan theta1)=d n2(sintheta3-costheta3.tantheta4)+(d n3/n3) tantheta4.costheta3.n2. |
