| 摘要 |
1,266,785. Holographic interferometry. NIPPON KOGAKU K.K. March 11, 1969 [March 14, 1968], No. 12726/69. Heading G2J. In a method of double-exposure holographic interferometry to measure the difference between two states of an object, a hologram H. G. is formed by interference between an information beam from object S with a first reference beam (from mirror M 1 ) and then at a later point in time by interference between the information beam and a second reference beam (from mirror M 2 ) at a different angle from the first; the two images of object S are reconstructed simultaneously and are superimposed thus forming interference fringes indicative of the difference between the two states of the object; compensation for lateral displacement between the two states, and to ensure coincidence of the two images, is obtained by tilting one of the reconstructing reference beams. Preferably the two reference beams are polarised perpendicular to each other. Measurement can be made by moving the hologram plate H. G. to give a shift in the fringes. Alternatively the reconstructed images can be formed at a Savart Plate S. P. in the focal plane of a lens O 2 . |
