| 摘要 |
The invention concerns an optical device (2) for characterising a diffractio n grating (14) consisting of first and second integral interferometric diffraction sensors (4, 6) spaced apart from each other by a first specific distance, and comprising each a reading system (10a, 10b) and at least a lig ht intensity detector, said first and second sensors delivering respectively first and second electric signals which, during the relative displacement (.DELTA.x) between the device and the diffraction grating, vary in accordanc e with the spatial frequency of said grating in first and second regions there of located respectively opposite the two reading systems and receiving each lig ht supplied by at least one light source. In particular, the first and second electric signals define first and second phases of the first and second sensors. Additionally, the device comprises means for measuring a difference between the phases of the first and second signals and means (24) for measuring the accumulation of said difference when the device moves along th e grating. The invention also concerns optical devices for determining the spatial frequency of a grating of a type similar to said device. The inventi on further concerns methods for making diffraction gratings using said device.< /SDOAB>
|
