Dual-mode variable-array imaging interferometer testbed for the MEAYIN program

There has been growing interest in searching for habitable planets around stars in our neighborhood with mid-infrared light. In 2018, China proposed the Multiple-spacecraft Exoplanet Aperture sYnthetic INterferometer (MEAYIN) program by deploying a space-based rectangle-formation array of collector spacecraft and an additional beam-combiner spacecraft in the Sun-Earth L2 libration point. To advance the MEAYIN program, it is necessary to conduct preliminary laboratory research on phased array imaging interferometry. Here, we established a dual-mode variable-array imaging interferometer testbed (DVIIT) to study the phased array imaging technique with an optical model for simulation. The optical model, verified by the testbed, is expected to provide guidance for future space-based applications. The DVIIT is designed to be compatible with both Fizeau and Michelson interferometric modes, utilizing a white light of 400-900 nm and a varying array function to enhance UV coverage. It should be noted that this is the first, to our knowledge, experimental realization of Fizeau interferometric imaging under variable arrays with an FOV of 1 arc-minute. The optical model and experimental data are expected to support the design of a space-based platform and the development of image synthesis and restoration algorithms for the MEAYIN program.