OPTICAL ELEMENT, ITS PRODUCTION AND OPTICAL HEAD

摘要

PROBLEM TO BE SOLVED: To provide an optical element which has little warping, good precision of the transmitted wave front and an optical property that the diffraction efficiency to ordinary light is different from that to abnormal light and to realize the miniaturization and cost down of the optical head by using the optical element. SOLUTION: The optical element having little warping is produced by providing a lithium niobate substrate 1, proton-exchanged layers 2 which are formed by proton-exchanging the prescribed parts of X-face or Y-face of the crystal of the lithium niobate substrate 1 and a proton-exchanged layer 3 which compensates the stress of the lithium niobate substrate generated by the proton exchanged layers 2. Thereby, in the optical element having an ion exchanged layer in which diffraction occurs, the optical element having little warping and giving no aberration on transmitted wave front can be produced.