| Popis: |
Describes a simple method for nearly simultaneous measurement of a laser source spatial degree of coherence and coherence length. Modifying the Twymann-Green method, and after a 180 degrees rotation of one of the split beams, it is possible to produce interference around the optical axis between both split beams. By means of the modulation of fringes close to a given point it is then possible to determine the complex amplitude degree of correlation at that point with respect to its axis related symmetry point. It is also possible to measure the coherence length by observing the central field modulation by simple translation of the nonlens associated mirror. Finally, the use of a photomultiplier in the observation plane allows the evaluation in real time of the modulation of fringes at any point of the field. |
