METHOD AND APPARATUS FOR CONDUCTING DIRECT PHASE MEASUREMENT OF ELECTROMAGNETIC RAYS, PARTICULARLY LIGHT RAYS

摘要

PURPOSE: To enable perfect measurement of a phase by radiating a coherent electromagnetic line with a specified frequency to an object to detect the phase of the electromagnetic line from the object from intensity signals of at least three sensor elements. CONSTITUTION: A coherent electromagnetic line 2 with a specified frequency is radiated to an object 3 having a diffusively reflecting surface 4. Then, the electromagnetic line 5 reflected from the surface 4 of the object 3 forms an image on the plane 7 of an image through an image formation optical device 6. The plane 7 is provided with a sensor 8 having a plurality of sensor elements 9 regularly arranged. Desirably, the device 6 is so set that an image of a small spot 12 produced on the surface 4 of the object 3 by the electromagnetic line 2 covers at least three sensor elements 9 of the plane 7. In other words, the small spot 12 covers at least three sensor elements 13-15. Thus, the phase of the electromagnetic line 5 can be detected from the surface 4 of the object 3 using a calculating means by intensity signals of at least the three sensor elements 13-15.