Phase invariance in a recently proposed common-path laser interferometer

This study shows that the principle of a recently proposed common-path laser interferometer containing a planar grating is nonexistent and apparently caused by a mathematical derivation error. Both p-and s-polarized beams in the proposed setup experience once the +1st-order diffraction and once the-1st-order diffraction by the grating. As a result, the phase of each beam remains unchanged and the interference fringes formed by the two beams are not expected to move when the grating is translated in the grating vector direction. We perform an experiment to confirm this prediction. Both our analysis and experimental observation cast doubt on the experimental results of the authors who proposed the interferometer.     

基于DSP的嵌入式在线振动信号分析系统

为监测机械设备的工作状态,对机械设备工作过程中产生的振动信号进行采集、处理和分析,从而实现系统的状态监测、故障诊断以及寿命预测等。但目前振动信号分析系统体积较大、不方便携带,多用于离线的振动信号处理,难以完成机械设备振动信号的在线实时分析。针对振动信号离线分析系统存在实时性低、体积大等不足,设计了基于TMS320C6713 DSP的嵌入式振动信号采集处理系统,以满足机械设备振动信号采集、处理和分析过程中对采集、处理实时性,系统便携性等需求。详细介绍了系统的软硬件设计原理和方法,利用美国凯斯西储大学的公开轴承测量数据集对系统的各项功能和技术指标进行实验验证。实验结果表明,该系统能够正常工作且可应用于实际工程中。另外,系统支持功能和算法扩展,以满足不同机械设备的振动信号采集、处理和分析需求。