Patent ID: 7842132

Claim:
A method for producing an optical element for converting light of prescribed wavelength emitted from a light source into light of wavelength different from the prescribed wavelength; the method comprising: optically polishing a first crystal part including KTiOPO 4 or quartz and a second crystal part including YVO 4 doped with Nd so that surfaces opposed to each other have coefficients of linear expansion different by 5 ppm or more and the surfaces opposed to each other include crystallographic axes; applying an acrylic adhesive whose glass transition point is 75° C. or lower to a surface of the first crystal part or the second crystal part; placing the first crystal part abutting the second crystal part with the adhesive applied in the applying step therebetween and irradiating the adhesive with light to cure the adhesive, and form an adhesive layer having a refractive index of greater than 1.49 and less than or equal to 1.52; and cutting the first crystal part and the second crystal part stuck to each other through the adhesive layer to a desired size.