数字全息是用数字的方式记录和处理全息图像，通常在使用双曝光法测量物体微小形变时，对于形变量接近入射波长一半的情况一般使用相移的方法，这种方法需要拍摄多幅全息图。为了简化过程，提出将灰度值和双曝光方法相结合测量物体的微小形变。该方法通过画出条纹图的灰度曲线，判断条纹级数，计算出物体形变量;只需拍摄两幅全息图。通过理论分析和实验验证，取得了满意的结果。结果表明，该方法在一定的范围内是可行的。

The usual method for recording and processing hologram images is digital holography, which is also suitable for double-exposure to measuring object deformation. However, the deformation near half of the optical wavelength is based on phase-shift method, and it needs more than three hologram images. In order to simplify the method, the double-exposure with gray-level was extended to measure deformation. By using the gray-level, with the image of gray-level distributions, the fringe numbers can be calculated and then the out-of-plane displacement was obtained. This method only needs take two images. Through theoretical analysis and experimentation, the result is satisfactory, which show this method works well in a certain extent.