OPTICAL ELEMENT AND OPTICAL PICKUP DEVICE USING THE SAME

摘要

PURPOSE:To obtain the optical element having two functions; a lens function and another optical function, by forming synthetic grating patterns constituted of two kinds of the grating patterns which vary from each other and are superposed on each other on a substrate. CONSTITUTION:The synthetic grating pattern constituted of two kinds of the grating patterns which vary from each other and are superposed on each other are formed on the substrate 10. The gratings are obtd. by a relief type (or corrugation type) which generates the diffraction of light by the projecting lines and recessed grooves on the surface of the substrate 10 or a distributed index type which generates the diffraction of light by a change in the refractive index of the substrate. The optical element having the two functions; a lens function and another optical function, is obtd. in this way.