DIFFRACTIVE OPTICAL DEVICE AND METHOD FOR PRODUCING SAME

摘要

A practical diffractive optical device is efficiently produced at a low cost. A modulated refractive index diffractive optical element comprises a transparent DLC (i.e. diamond- like carbon) film (2) formed on a transparent substrate (1), and the DLC film (2) includes a diffraction grating having a local region (2a) of a relatively high refractive index and a local region (2) of a relatively low refractive index. The DLC film (2) can be easily deposited on the substrate (1) by plasma CVD, and the relatively high refractive index region (2a) in the DLC film can be easily formed by irradiating the film with an energy beam (4) such as an ion beam.