Effect of Minimum Baseline Length on Integrated Interferometric Systems
Objective The angular resolution of an optical system is inversely proportional to the aperture size of the telescope.However,increasing the telescope's aperture places higher demands on precision manufacturing,and large aperture systems often require complex mechanical structures.This leads to high production costs,longer manufacturing cycles,and stricter rocket launch requirements during orbital deployment.Therefore,achieving lightweight and low power consumption while maintaining high resolution is a critical challenge for optical systems.To address this,researchers at Lockheed Martin and the University of California,Davis,have proposed integrated interferometric imaging technology.By combining the microlens arrays with photonic integration chips,they process optical signals from matched lenses to capture complex coherence across multiple spatial frequencies,corresponding to the far-field target.Using the van Cittert-Zernike theorem,the light intensity distribution of the observed target is reconstructed through inverse Fourier transformation.Current research on integrated interferometric systems mainly focuses on three areas:microlens array structures,photonic integrated chip designs,and image recovery algorithms.These studies have primarily focused on the simulation process of the photonic integrated interference system.However,they only consider the coupling efficiency from the microlens array to the optical waveguide as the limiting factor of the field of view,without adequately investigating the influence of spatial aliasing caused by the discrete spectral distribution.To address this gap,we examine the effect of the minimum baseline length on imaging in integrated interferometric systems,which is crucial for advancing their practical application.Methods The study involves both theoretical analysis and computer simulation.First,we construct a frequency domain filter and perform an inverse Fourier transform to obtain the spatial convolution kernel of the integrated interferometric system.We then analyze this convolution kernel to determine the maximum object field width that prevents spectral aliasing.A computer simulation process is designed to verify these theoretical conclusions.This simulation includes the following steps.First,the observation image is input,followed by the construction of the microlens array based on the existing cobweb layout.Next,the coupling efficiency for each object field,corresponding to different microlenses at various positions,is calculated using the coupling efficiency formula.Then,interferometric baselines of different lengths are constructed through head-to-tail matching,and the complex coherence is achieved using the four-step phase-shifting algorithm.The image is then reconstructed using the inverse Fourier transform,which is used to calculate the image width.Finally,the quality of the recovered image is evaluated using root mean square error(RMSE)and peak signal-to-noise ratio(PSNR).Results and Discussions Based on the sampling theorem,we analyze the field of view of the integrated interferometric system,highlighting the spatial aliasing effect caused by head-to-tail matching of microlens arrays.The relationship between the minimum baseline length and the field of view is then derived.Based on the principles of the integrated interferometric system,a simulation process is developed to enable imaging of the observation target by adjusting the minimum baseline length.The simulation results demonstrate that when the minimum baseline length exceeds the field of view limit,the system's imaging quality significantly degrades due to spatial aliasing.This confirms the constraint between the minimum baseline length and the field of view size.Conclusions The analysis demonstrates that increasing the minimum baseline length improves the system's resolution.However,surpassing the maximum field of view limit leads to rapid degradation in imaging quality due to spatial aliasing.Therefore,while increasing baseline length improves resolution,the limiting effect on the field of view must be carefully considered.By adjusting microlens spacing,two operating modes are proposed:short-baseline for a large field of view and long-baseline for a small field of view.This strategy aims to optimize the performance of integrated interferometric systems across various application scenarios.
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