Manufacture of diffraction grating on tiny parts by means of ultraprecision milling

The study deals with the manufacture of diffraction grating by applying the ultraprecision microgrooving technology. Microgrooving is performed by the use of a lathe-type ultraprecision milling machine having I nm positioning accuracy, together with a rotating diamond cutter. As an example of microg roove, a diffraction grating with 32 768 V-shaped grooves is fabricated in a pitch of 1 mu m and a depth of 0.5 mu m around the circumference of coppe r disk of 12 mm in diameter. The high-speed rotating cutter allows the micr ogrooves to be sharply machined without burrs and accumulative pitch errors , taking account of cutting order. The surface roughness of machined groove s is 1 nm (Ra), which experimentally shows good optical properties.