【摘要】 本文提出一种采用光栅对立体像对进行空间滤波产生等高线的相干光学方法。从理论上分析了视差与谱面上光振幅分布的关系、空间滤波的作用以及滤波后像面上的光振幅分布。把立体像对的振幅透过率在4f系统物面上叠加,并用相干光照明,在频谱面上会得到多组不同频率的干涉直条纹。每一组条纹都对应一群视差相同的点,即一条等高线。用一块光栅进行空间滤波,让某一组干涉条纹透过光栅,而挡住其它条纹,在像面上就会出现一条等高线。不同的光栅间隔对应着不同位置的等高线。改变光栅位置,等高线会发生明暗变化。实验采用了斜面和圆锥两种模型,分别得到了直线和圆环状等高线。文中给出了不同位置和不同明暗的等高线的实验结果。这种方法不需要逐点测量视差,因而具有快速的优点。实验中用非相干方法把立体像对重叠在一张照相干板上,达到振幅相加,以降低对系统的要求。更多还原

【Abstract】 A coherent optical method for generating contours from stereophotographs by using a grating as a spatial filter is proposed. The relationship between parallax and light amplitude distribution in the spectrum plane, the effect of spatial filtering and the final light amplitude distribution in the image plane are analysed theoretically. The superposition of the amplitude transmittances of the stereophotographs in the object plane of a 4f system, when illuminated with a beam of coherent light, will result in numerous sets of straight interference fringes in the spectrum plane, with each set coresponding to a set of points with the same parallax, i. e., a contour line. When a grating is used to provide spatial filtering, only one set of fringes is allowed to transmit through the grating, while others are blocked off. Then a contour will appear in the image plane of the system. Different grating spaoings corespond to different contour positions and a change In the position of the grating will lead to bright or dark contours. Stright and circular contours are obtained by using two experimental models, a slope and a conic. Experimental results with contours in different positions and having different values of brightness are given in the paper. Because it is unnecessary to measure parallax point by point, the method has the advantage of quickness. In our experiment, two stereophotographs are superposed on one photosensitive plate incoherently to achieve amplitude addition so as to reduce the requirement on the system.更多还原