Fig. 1. Comparison between conventional ptychography and SAP. Conventional ptychography translates the object over a confined probe beam in the spatial domain and acquires diffraction data at the far field. During the reconstruction process, conventional ptychography stitches the information in the spatial domain to expand the field of view. SAP illuminates the stationary object with an extended plane wave and translates a coded sensor at the far field for data acquisition. In the reconstruction process, SAP stitches the information in the intermediate aperture plane for object recovery. It can widen the field of view in real space and expand the spatial-frequency bandwidth in reciprocal space at the same time. The dashed arrows present free-space propagation over certain distances.

Fig. 2. Reconstruction process of SAP. The acquired images are used to update the specific regions of the exit wavefront W(x,y) at the intermediate aperture plane. After recovery, we backpropagate the exit wavefront to the object plane for image recovery. The object reconstruction process of SAP can widen the imaging field of view in real space and expand the Fourier spectral bandwidth in reciprocal space at the same time.

Fig. 3. Transmission and reflection configurations for SAP. For both configurations, the coded sensor is translated by a mechanical stage in the Fresnel zone. (a) Transmission configuration. The object exit wavefront synthesized at the intermediate aperture plane is backpropagated to the object plane for image recovery. (b) Reflection configuration. The coded sensor is translated in the direction perpendicular to the zero-order reflective beam. The recovered wavefront is then backpropagated to the object plane with a 20° tilted angle. (c) Employed coded image sensor. Two mask-free regions are used to track the positional shift in x and y directions.

Fig. 4. Experimental validation of the transmission configuration of SAP. (a) Recovered wavefront W(x,y) at the coded layer plane. By stitching together different numbers of measurements, we can synthesize images with a size of 5.5 mm (a1), 11 mm (a2), and 20 mm (a3). (b) Recovered wavefront backpropagated to the object plane. The recovered objects in (b1)–(b3) correspond to the synthesized wavefronts in (a1)–(a3). (c) Fourier spectra of the recovered objects. The expanded spatial-frequency bandwidths are highlighted by dashed circles.

Fig. 5. Experimental validation of the reflection configuration of SAP. (a) Recovered wavefront W(x,y) at the coded layer plane. By stitching together different numbers of measurements, we can synthesize images with a size of 5.5 mm (a1), 11 mm (a2), and 20 mm (a3). (b) Recovered wavefront backpropagated to the object plane with a tilted angle of ∼20°. (c) Recovered phase corresponding to (b).