Optical-Carried Microwave Scanning Interferometry Ranging Method Based on Real-Time Amplitude Spectrum Detection

Distance measurement technology is of great significance to scientific research and industrial production. As an emerging technology, optical-carried microwave scanning interferometry (OCMSI) technology has been applied in the field of high-precision distance measurement. However, OCMSI ranging often requires the aid of the vector network analyzers (VNAs), which limit the instrumentation and modularization of the OCMSI ranging system. To overcome this, the OCMSI amplitude spectrum detection and calculation technology is proposed in this article. First, a miniaturized real-time amplitude detection unit (ADU) is designed to demodulate the amplitude of the optical-carried microwave interference signal efficiently. The amplitude of this signal is converted into the amplitude spectrum containing distance information. Furthermore, the multisegment synthetic Fourier series fitting (MSFSF) algorithm is proposed to achieve the high accurate and repeatable distance calculation. In the 10 m range, experiments of measurements for various distances are promoted, the ranging accuracy is $\pm ~0.052$ mm and the repeatability is 0.019 mm. These two indexes for the OCMSI ranging results are essentially in the same order of magnitude as using VNA. The experiment shows that the proposed OCMSI ranging method is of great significance to the related technologies promotion in practical applications.