. Carnegie Institution of Washington publication. 66 DISPLACEMENT INTERFEROMETRY APPLIED TO well as by the micrometric shifting of the interferometer mirrors Nr or Mr. There are thus two independent methods, apart from the ocular reading of displaced fringes. The fringes from mm and nn may be made parallel by rotating nn on a horizontal axis. If they are visible for the same micrometer position, the glass paths must be rigorously the same in the two cases, so that optic plate is needed. To make the fringes of the same size a vertical axis at nn suffices. it r xt/J' \ _. ^ ' m, /«*' , \ 6^ \ \w
. Carnegie Institution of Washington publication. 66 DISPLACEMENT INTERFEROMETRY APPLIED TO well as by the micrometric shifting of the interferometer mirrors Nr or Mr. There are thus two independent methods, apart from the ocular reading of displaced fringes. The fringes from mm and nn may be made parallel by rotating nn on a horizontal axis. If they are visible for the same micrometer position, the glass paths must be rigorously the same in the two cases, so that optic plate is needed. To make the fringes of the same size a vertical axis at nn suffices. it r xt/J' \ _. ^ ' m, /«*' , \ 6^ \ \w' r 91 t/Tv m P1" 73t -n,. 58. Lens train. — This would be peculiarly difficult to apply in the present case. As a large field of view is desirable, a collimator will be needed. If F is its external focus, supposed to be on m (fig. 92 vertical plane, 93 plan), the lenses L can not be of very different focal power from the collimator, if too much light is not to be lost at the edges. If fl and fa are the focal distances, the total distances apart of the mirror m and n would not much exceed 2^-f 2 fa. It would probably not be advantageous to make this exceed 5 meters and lenses of large diameter would be needed. The main difficulty, however, is the introduction of one of these trains into each of the component beams, in particular as it implies the insertion of uncertain glass paths for the rays. In fact, though I obtained very good slit-images from each beam, the result for two beams conjointly was inadequate. 59. Estimate. — It is finally of interest to ascertain the sensitiveness of an arrangement like figure 91. If the distance 5 of mm from nn is passed in A* seconds, and v is the velocity of light, 28 = v A* and A*/ 7= A0/27r,if the angu- lar displacement A0 corresponds to A* and T is the period of the mirror. Fur- thermore, on the interferometer A0 = A/V cos t/b, where b is the breadth of the ray parallelogram, i the angle of incidence at the mirrors and AJV the m
Size: 1798px × 1389px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1900, bookyear1902
