Fig. 1. Single-shot NLOS imaging based on chromato-axial differential correlography. (a) Principle diagram of the method. (b) Schematic sketch of the system. (c) Chromato-axial difference: the correlation coefficients between the laser speckles of 450 nm and 520 nm, 450 nm and 640 nm, 520 nm and 640 nm are 0.0095, 0.0039, and 0.0014. The uncorrelated laser speckles encode the hidden object.

Fig. 2. Single-shot hidden object reconstruction method. (a) Flowchart of the proposed autocorrelation estimate method. (b) Camera image segment experiment to improve the availability of autocorrelation estimate in phase retrieval algorithm by sacrificing spatial resolution.

Fig. 3. Simulated single-shot NLOS imaging on character objects and complex objects. (a) Simulated imaging experiments on character objects. (b) Simulated imaging experiments on complex objects. The simulated chromato-axial differential speckles are used to calculate the autocorrelation estimates of the hidden objects. The hidden objects are reconstructed with the HIO phase retrieval algorithm. Character objects contain only simple structures and binary information. Fashion objects are used as complex objects, containing complex structures and grayscale information.

Fig. 4. System setup. Light passes from the lasers to the VS, to the hidden object, to the VD, and is finally captured by the camera. The intermediary wall is painted with latex paint.

Fig. 5. Practical imaging results. (a) Hidden objects used in this work and their autocorrelation. (b) Imaging results of the multi-shot method. (c) Imaging results of the proposed method.

Fig. 6. Experimental results of system vibration perturbation and hidden object reconstruction. (a) Schematic diagram of system vibration perturbation experiment. (b) Comparison of multi-shot method and single-shot method.

Fig. 7. Experimental results of wall chromato-perturbation and hidden object reconstruction. (a) Disturbed wall with different watercolor paints. (b) Spectral curve of the disturbed wall (three laser sources illuminated). (c) Camera image, estimated autocorrelation, and reconstruction under different chromato-perturbation.