Digital phase demodulation in heterodyne sensors
Digital phase demodulation in heterodyne sensors
复制标题
外差传感器中的数字相位解调
DOI：
10.1117/12.212980
复制
发表时间：
1995
影响因子：
1.3
通讯作者：
C. P. Burger
中科院分区：
文献类型：
--
作者：
James A. Smith;C. P. Burger
数字相位解调是一种灵活的外差解调技术，可用于动态位移的在线检测。利用计算机算法对来自外差干涉仪的数字化调制载波和参考载波信号进行解调以获得表面位移。由于在计算机中执行信号解调，因此可以容易地针对期望的检测中心频率优化载波信号的外差拍频或中心频率，并且外差拍频不必稳定。相对于干涉仪中使用的光的波长校准所得到的测量位移，并且对于大于光的波长的位移保持准确。没有假设的边带频率内容或表面位移的幅度。这里介绍的研究介绍了数字相位解调的概念，并显示了初步的实验结果，从外差干涉仪，同时监测振动和超声位移。初步结果表明，外差传感器系统能够测量大于三个波长的光的位移，并具有优于7 nm的单次拍摄分辨率。因此，数字相位解调将允许单个仪器监测由低振幅、高频超声和由高振幅、低频振动产生的位移。
Digital phase demodulation is being developed as a flexible heterodyne demodulation technique for on-line dynamic displacement detection. The digitized modulated carrier and reference carrier signals from a heterodyne interferometer are demodulated for surface displacements using computer algorithms. Since the signal demodulation is performed in the computer, the heterodyne beat frequency or center frequency of the carrier signals can be easily optimized for the desired detection center frequency and the heterodyne beat frequency does not have to be stable. The resulting measured displacements are calibrated with respect to the wavelength of light used in the interferometer and remain accurate for displacements larger than the wavelength of light. No assumptions are made about the sideband frequency content or the amplitude of the surface displacements. The research presented here introduces digital phase demodulation concepts and shows initial experimental results from a heterodyne interferometer while monitoring vibrational and ultrasonic displacements. The initial results show that the heterodyne sensor system is capable of measuring displacements greater than three wavelengths of light and has a single-shot resolution better than 7 nm. Thus digital phase demodulation will allow a single instrument to monitor displacements produced by low-amplitude, high-frequency ultrasound and by high-amplitude, low-frequency vibrations.