| 摘要 |
An identification mark is made on a transparent workpiece, such as a lens for spectacles, by irradiating the material in a pattern desired for an identification mark with radiations which produce localized permanent stresses in the material that are visible by double refraction in polarized light. Suitable irradiation may be provided by corpuscular radiation, as by an electron beam, or electromagnetic radiation, as by laser beams. The radiation is preferably applied in an amount to produce the stresses within the material, not on the surface. |
