提出了利用双波长数字全息实现对微光学元件刻划凹槽的三维成像。由两个不同波长的激光记录所得到的两幅数字全息图分别通过数值再现得到其对应波长的包裹相位图，再通过双波长解包裹得到等效波长的相位图，由该相位图重构出被测物体的三维形貌。通过数值模拟验证了双波长数字全息方法的可行性，并通过搭建双波长数字全息实验系统，利用632.8 nm和671 nm两个波长的激光对微光学元件刻划凹槽进行了三维成像，得到的刻划凹槽平均深度为7.1 μm，其结果与表面轮廓测量仪获得的三维形貌和凹槽深度都具有较好的一致性，证明了双波长数字全息三维成像结果的有效性。

The three-dimensional (3D) profiles of a plate with many micro grooves is obtained by using dual-wavelength digital holography. Two individual phase images are obtained by using two different wavelengths, respectively, and the phase image for beat wavelength is obtained after dual-wavelength phase unwrapping. Then the 3D profiles can be obtained through the phase image of the beat wavelength. This method is demonstrated by both numerical simulation and experiment. In the experiment, two lasers of the different wavelengths 632.8 nm and 671 nm are used to obtain a larger beat wavelength. The object is a plate with many micro grooves. The result shows that the average depth of the groove is 7.1 μm. This is in good agreement with the result given by the profilometer. It demonstrates that the 3D imaging result by using dual-wavelength digital holography is effective.