Visualizing Small Objects Using Amplitude-Modulated Laser Light at Microwave Frequencies

We reported on laboratory imaging experiments conducted using a system that utilizes amplitude-modulated infrared laser light at microwave frequencies. With modulations ranging from 11.1 to 15.1 GHz on a 1.55 μm near-infrared laser, the phase measurements of the modulation signals revealed a target shape with sub-mm precision. We also tested whether our system is able to achieve cross-range resolution in the spot-light mode synthetic aperture scheme. With the aid of “position-compensated signal processing”, synthetic aperture images were formed successfully. According to predications based on the principle of normal synthetic aperture radar, the spatial resolutions of the images were shown to be inversely proportional to the width of the collected data placed in the wavenumber space.