通过两个不同波长的数字全息包裹相位差产生数字拍频，得到一个等效波长相位图以消除相位包裹，然后用该等效波长相位光程与任一记录波长做比较，确定单波长包裹相位中相位跳变的位置和跳变倍率，进而实现了单波长包裹相位展开，使相位噪声不随等效波长相位展开而放大，结果表明该方法可使相位噪声引入的误差减小2Λ/λm倍。用650 nm和632.8 nm两个波长的激光对用快刀伺服加工的微结构光学元件表面进行了数字全息测量，得到了等效波长为0.024 mm的加工纹理相位展开图，并用频谱滤波得到了元件微观形貌的低频和高频三维数据，各频段表面的粗糙度分别为33.2 nm，19.3 nm，23.4 nm，分析了各种微观结构产生的原因，并对快刀加工的切削参数进行了分析。%Through the subtraction of two digital holographic wrapped phases for different wavelengths, it yields a beat phase image corresponding to an equivalent wavelength to remove the phase wrapping. By comparing the beat phase image with any recoding wavelength, the position and multiple of the single wavelength phase jump are confirmed. Hence, the wrapped phase in single wavelength phase is wrapped and the phase noise is kept fixed. Simulation and experimental results demonstrate the measure error induced by the phase noise can be reduced to 2Λ/λm. An optical microstructure element surface is measured by the proposed digital holography with dual wavelength of 650 nm and 632.8 nm. The measured optical element is produced with Fast Tool Servo (FTS). The unwrapped phase image of machining mark on the surface of microstructure element is acquired clearly. The equivalent wavelength is 0.024 mm. Then, the three dimensional data of the microstructure profile respectively in high frequency and low frequency regions are obtained by frequency filtering. The roughnesses corresponding to different frequency region are 33.2 nm, 19.3 nm and 23.4 nm respectively. The affecting factors for different machining mark are analyzed. The cutting parameters of the FTS are also deduced.
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