| 摘要 |
<p> The disclosure is directed to an apparatus and method for obtaining an improved moire fringe pattern image of an object. A beam of incoherent light is projected at the object, A first grating (21, G1), referred to as a projection grating, is disposed in the path of the beam projected at the object. A lens (30, LO) is provided for focusing the beam reflected from the object to obtain an image at an image plane. Another movable grating (35, GO), referred to as a reference grating, is disposed at the image plane. Means (40) are provided for recording the image at the image plane, the recording means being, for example, a photographic orvideo camera. In accordance with an important feature of the invention, means (50, 310) are provided for moving the projection grating and the reference grating in synchronism. In a preferred embodiment, the projection and reference gratings are mounted in spaced relation in a movable member, and the synchronized motion of the gratings is implemented by moving the member. In one form of the apparatus and method, a double-projection system is used wherein two projection beams are directed at the object through first and second movable projection gratings (G1, G2), respectively. In this embodiment, the first and second projection gratings are moved in synchronism with the reference grating (GO). This is preferably achieved by mounting the three gratings in appropriate spaced relationship in a common member (310), and moving the member.</p> |
