| 摘要 |
PROBLEM TO BE SOLVED: To enable high-precision alignment at low cost through less arithmetic processing. SOLUTION: A phase mask 12 is formed on a part of a photomask 10. Array intervals of respective grooves 14 constituting the phase mask 12 are uniformly varied in the direction along which those grooves 13 extend. The photomask 10 is arranged opposite a substrate 16 at light irradiating. On the top surface 16a of the substrate 16, one groove 18 is formed extending linearly. A photosensitive optical fiber 20 is fixed while being fitted in the groove 14. Then the substrate 16 and photomask 10 are temporarily positioned, so that the phase mask 12 and photosensitive optical fiber 20 are put one over the other. Then the photosensitive optical fiber 20 is irradiated with light through the phase mask 12 to form a diffraction grating. Light is guided to the formed diffraction grating and its spectrum is measured. The center wavelength of this spectrum varies in accordance with the cycles of refractive index variation, so that the quantity of the phase shift between the photomask 10 and substrate 16 can be calculated. |
