Remote Sensing
We develop an imaging method based on the pink noise pattern in the Computational Ghost Imaging (CGI), which has a strong ability to photograph moving objects with the point detector. The idea is experimentally demonstrated by making a CGI measurement on a moving flight. To examine its unique ability and scope of application, the flight oscillates with variable amplitude in horizontal axis, and a group of results via commonly applied white noise are offered. There do exist some special circumstances where only applying red noise can clearly image the object. Our method is also able to employed with less number of patterns, and enhances the signal-to-noise ratio (SNR) to a great extent.
We prepare pink and white noise patterns same as the project 'Noise-free Imaging', and utilize the Non-zero cross-correlation feature as well.
Fig. 1. Flow Chart of pink and white noise pattern generation; and their features of correlation.
We set the distance of motion as 0mm, 0.4mm, 0.9mm, 1.8mm, 2.7mm, which correspond to 0, 2, 5, 10, 15 independent changeable pixels of noise patterns projected on CCD surface. For each group, pink noise and white noise are applied, and CGI results are achieved from variable sampling numbers (N = 1000, 2000, 5000, 10000). In addition, we introduce SNR to justify the quality of results. Traditionally, the definition of SNR = μsig / σsig, where the μsig is the average signal value and the σsig is the standard deviation of the signal. The main results are in Fig. 2 and Fig. 3.
Fig. 2. The results are achieved by sampling 10000 patterns. (a) the white noise CGI result with static target. (b): the pink noise CGI result with static target. (c): the white noise CGI result with displacement = 1.8mm. (d) the pink noise CGI result with displacement = 1.8mm.
Fig. 3. All the results above are sampled with the displacement of the target equaling to 0.9mm. The number of sampling are shown on the title. (a)-(d): results of pink noise CGI. (e)-(h): results of white noise CGI. (i): signal to noise ratio of figure (a)-(h).
These results provide the basis of pink noise CGI to capture and reconstruct the target at a very fast speed.
Fig. 4. signal to noise ratio of moving distance equal to 0mm, 0.4mm, 0.9mm, 1.8mm, 2.7mm. The dashed lines represent SNR of white noise results; the solid lines represent SNR of pink noise results.
Thus, we have developed a practice based on the pink noise pattern in CGI system to reconstruct images of a moving object, which is indicated by the simutaneously improved SNR and fewer sampling number. Experimentally, the SNR of pink noise CGI is usually 4 to 5 times higher than the SNR of white noise CGI when N is less than 2000.
Moving Object Captured with Pink Noise Pattern in Computational Ghost Imaging.pdf
https://arxiv.org/abs/2012.07284
