Efficient Back-Projection Technique for Multiple Objects Detection and 2D Imaging Through Photonics-Based LFM Radar

Detection and imaging play a vital role in modern radar technology and have seen significant interest across various fields, including autonomous vehicles, defense, environmental monitoring, and weather forecasting. This work presents a method for the detection and imaging of multiple objects positioned at uniform and non-uniform distances within a defined region of interest. Linear Frequency Modulated (LFM) waveform, which features excellent pulse compression capability is employed in this work. We use an injection of external beam into a Distributed Feedback (DFB) laser to generate LFM waveform and further detect and estimate the range of multiple targets along the longitudinal axis. Additionally, by taking multiple range measurements along the lateral axis, we extend this approach to estimate lateral distances, thereby achieving a comprehensive 2D imaging solution. Using an efficient back-projection technique, we reconstruct a two-dimensional image of the detected objects by leveraging range measurements from a single dimension. Specifically, we leverage filtering and intensity projection to improve classical back-projection. For a proof-of-concept validation, an 8 GHz bandwidth LFM signal centered at 12 GHz is employed to detect objects within the designated space which is further implemented for imaging using proposed efficient back-projection technique. Our proposed imaging method solves the problem of signal bleeding and collapsing and enhances image resolution by utilizing received signal data, achieving an error margin within 3 mm along the longitudinal axis and 9 mm along the lateral axis relative to the actual value with single-dimension measurements. Furthermore, the proposed technique obtains the maximum error reduction of 100% in X-direction and 95% in the Y-direction compared to the conventional method.