# Parallel Ghost Imaging with Extra Large Field of View and High Pixel Resolution
## 1 Introduction  
Light emitted by an object passes through an optical system to form an image, as seen in the human eye, cameras, and lenses. All of these fall within the category of classical imaging. These systems generally consist of three key components: the light source, the object, and the optical system. In contrast, ghost imaging (GI), a novel imaging technique, employs a non-local imaging approach that enables the separation of detection and imaging. In this work, we further explore the non-local characteristics of ghost imaging, expanding the separation between the detector size and the imaging field of view. Ghost imaging is a development of the intensity-intensity correlation concept (intensity interferometry) pioneered by [PERSON] and [PERSON] [1, 2]. In 1988, [PERSON] [3] theoretically proposed a ghost imaging scheme using entangled photon pairs. In 1994,Ribeiro et al. [4] discovered ghost interference phenomena through entangled photon pairs. In 1995, [PERSON] et al. [5] experimentally realized ghost imaging using entangled photon pairs. In 2002, [PERSON] et al. [6] demonstrated ghost imaging with classical light sources, proving that entangled light sources are not a necessary condition for ghost imaging. Furthermore, GI has shown feasibility in various fields [7; 8; 9], including atomic [10], electronic [11], neutron [12; 13], and X-ray imaging [14; 15; 16; 17; 18; 19]. In 2008, [PERSON] [20] theoretically proposed the concept of computational ghost imaging, making single-path ghost imaging possible. In 2009, [PERSON] et al. [21] experimentally realized computational ghost imaging. That same year, [PERSON] et al. [22] combined the technique of compressed sensing from the field of image processing with computational ghost imaging, significantly reducing the number of measurements needed for acquisition. This breakthrough enabled the reduction of radiation doses in X-ray-based ghost imaging. However, if GI wants to reconstruct high-resolution images, it usually requires a large number of single pixel measurements, which poses difficulties for its practical application. Based on this, the concept of parallel ghost imaging (PGI) was proposed by [PERSON] et al. to solve this problem [12]. This method treats each pixel of a position sensitive detector as an independent bucket detector and performs tens of thousands of ghost imaging simultaneously in parallel in one measurement. [PERSON] et al. and [PERSON] et al., respectively, achieved PGI on neutron [12] and X-ray [23; 24]. [PERSON] et al. extended the concept of computational ghost imaging to multipixel ghost imaging with 80 keV X-rays from an X-ray tube and achieved a ghost image reconstruction with a field of view of 0.4 megapixels using only 1000 measurements. The results of this paper implicate that parallel ghost imaging has great potential in the fields of medical imaging and non-invasive measurement [25]. After that, we experimentally achieved parallel ghost imaging for the first time by using true magnification between the object arm and the reference arm [26]. This improved the imaging resolution of PGI and significantly improved experimental efficiency. In this study, while maintaining the 0.325 \(\upmu\)m pixel resolution and 6 min per sample experimental efficiency of parallel ghost imaging (PGI), we further expanded the imaging field of view and broke through the physical limitation of the reference arm's field of view for the first time. By collecting multiple sets of reference arm speckle patterns and performing seamless stitching, an ultra-large speckle space was constructed, ultimately achieving X-ray ghost imaging with 14,000 \(\times\) 10,000 pixels. After completing the pre-recording of the reference arm, the sample signal measurement was finished in only 6 min, successfully obtaining imaging results with a millimeter-scale field of view and sub-micron pixel resolution, along with excellent image quality.