在相位光时域反射仪中引入等时分双频光，提高扰动信号采样率，降低相邻相位的绝对差值，从而使得相位解缠绕正确实现，进而精确重构相位信号。然而，引入双频光使得初相位的不一致变得更加复杂，以致相位信号无法精确重构，即扰动信号的采样率难以真正得到提升。为此，在等时分双频光相位光时域反射仪中，基于模值最小值的乘积来快速确定参考位置并补偿脉冲序列方向初相位的不一致，对光纤长度方向初相位的不一致进行二次静态补偿。在实验中，当外界扰动为700 Hz的Burst信号时，使用单频探测脉冲光已无法进行正确解缠绕，而使用双重静态补偿方案的等时分双频光相位光时域反射仪却能够精确求解出Burst信号，且正弦部分的均方根误差仅为0.3872 rad，即在相位光时域反射仪中实现了信号采样率的双频光倍增和相位信号的精确重构。

A dual-frequency digital Moiré measurement method (DFDM) is proposed for the three-dimensional (3D) shape measurement of an object. The high- and low-frequency fringes are modulated separately along orthogonal direction using different carrier frequencies before being projected onto the measured object. After collecting and demodulating the composite fringe, the digital π phase shift is used to remove the DC component of the demodulated fringes, resulting in high-precision Moiré fringes for calculating the wrapped phase. The unwrapping of the high-frequency wrapped phase is guided by the low-frequency phase to further realistically reconstruct the surface of the measured object. When compared with existing single-shot digital Moiré profilometry, DFDM effectively removes the DC component of the fringe and calculates the phase more accurately.A dual-frequency digital Moiré measurement method (DFDM) is proposed for the three-dimensional (3D) shape measurement of an object. The high- and low-frequency fringes are modulated separately along orthogonal direction using different carrier frequencies before being projected onto the measured object. After collecting and demodulating the composite fringe, the digital π phase shift is used to remove the DC component of the demodulated fringes, resulting in high-precision Moiré fringes for calculating the wrapped phase. The unwrapping of the high-frequency wrapped phase is guided by the low-frequency phase to further realistically reconstruct the surface of the measured object. When compared with existing single-shot digital Moiré profilometry, DFDM effectively removes the DC component of the fringe and calculates the phase more accurately.

为了使用高频条纹实现对物体三维形貌高精度快速测量, 提出了一种利用双频外差和时空相位展开实现三维测量的方法。该方法仅投影两套高频条纹图片, 利用双频外差方法计算出一个频率较低的截断相位分布, 经空间相位展开得到其对应的连续相位, 用于指导高频条纹截断相位展开, 获得三维重建需要的绝对相位分布。该方法对双频外差后的低频截断相位上进行空间相位展开, 降低了空间相位展开难度, 增加了双频条纹投影三维测量的适用范围。实验结果表明该方法的STD误差为0.06 mm。该方法利用两套高频正弦条纹、不增加投影第三个频率条纹图的情况下, 实现了高精度快速三维形貌测量。