A starshade is a promising instrument for the direct imaging and characterization of exoplanets. However, even with a starshade, exoplanets are difficult to detect because detector noise, starshade defects, and misalignment (dynamics of the starshade system) degrade the signal to noise ratio (SNR) and contrast. No image processing methods have been specialized for images produced by a starshade system (simply referred as starshade images later). In this paper, we present a method, based on the generalized likelihood ratio test (GLRT), to detect and characterize planets from a single starshade image or multiple starshade images. This paper describes the GLRT model and its preliminary results for simulated images with starshade shape error, dynamics, detector noise and starshade rotation considered. The planets are detected with low false alarm rate, and planet positions are accurately estimated, and planet intensities are reasonably estimated. Thus, it demonstrates great potential as an acute and robust detection method for starshade images
A starshade is a specially designed opaque screen to suppress starlight and remove the effects of diffraction at the edge. The intensity at the pupil plane in the shadow is dark enough to detect Earth-like exoplanets by using direct imaging. At Princeton, we have designed and built a testbed that allows verification of scaled starshade designs whose suppressed shadow is mathematically identical to that of space starshade. The starshade testbed uses a 77.2 m optical propagation distance to realize the flight Fresnel number of 14.5. Here, we present lab result of a revised sample design operating at a flight Fresnel number. We compare the experimental results with simulations that predict the ultimate contrast performance.
Direct imaging using a starshade is a powerful technique for exoplanet detection and characterization. No current post-processing methods are specialized for starshade images and the ones for coronagraph images have not been applied to images produced by a starshade system ( starshade system means the light sources, starshade and telescope). Here, we report on the first step towards adapting these methods for starshade systems. We have built a starshade imaging model. We generate the image based on a simulation of the real astronomical scene and consider the effects of various starshade defects, misalignment, wavefront error, and detector noise. Future work will add the system dynamics of formation flying between the starshade and the telescope. The ultimate goal is to adapt coronagraphic image processing methods for starshade imaging.