| 摘要 |
PROBLEM TO BE SOLVED: To measure the phase difference of phase shifters in a short time by illuminating a phase shift mask with light of a prescribed wavelength, interfering this light with reference light to generate interference fringes and calculating the phase quantity of the phase shifters from the phase information of the phase shifter parts and non-phase shifter parts of these interference fringes. SOLUTION: The light emitted from a light source 1 having coherence is split to the reference light and the object light by a beam splitter 2. The object light is cast to the phase shift mask 5 and forms a phase shift mask image on a sensor 15 by an objective lens 7 and an image forming lens 13. On the other hand, the reference light is magnified by a mirror 3, a variable angle mirror 10 and lenses 11, 12 to a size which interferes with the object light on the sensor 15 which is two-dimensional CCDs and is cast as parallel luminous fluxes. The object light and the reference light are interfered on the sensor 15 and the interference fringe images are obtd. by an image processing section 16. The phase shift quantity is found with a phase calculation section 17 by using the images obtd. in this image processing section 16. |
