## 3 Results and Discussion
### Experiment Results  
The applicability of the proposed approach to tissue imaging was investigated on the basis of the results for an onion and the acinar cells of an orange, as shown in Figures 5 and 6, respectively. In Figures 5 and 6, one pixel in the \(x\) direction represents 10 \(\upmu\)m.  
Figure 4: (**a**) Schematic diagram of the simulated sample, (**b**) the reconstructed structural signals of the SD-OCT and ISAM obtained by 100% B-scan data, (**c**) under-sampled B-scan data in spatial domain with a sampling rate of 50%, (**d**) under-sampled B-scan data in the lateral spatial frequency \(Q_{//}\) domain, and (**e**) reconstructed structural signals of ISAM and SD-OCT using 50% data. Figure 5a,b are the structural images of SD-OCT and ISAM, respectively, reconstructed from the complete spectral data. We can find that the lateral resolution of the ISAM image is improved compared to the SD-OCT image, especially in the depth range away from the DOF. The blue and red curves in Figure 5e show the lateral distribution of the structures within the yellow dashed boxes at a depth of 550 \(\upmu\)m from the focal plane, respectively, in Figure 5a,b. Figure 5c is the image after reconstruction of the selected A-scans from 50% \(\times\) 50% spectral data. The 2D image shown in Figure 5d was reconstructed after performing steps 2-5 introduced in Section 2.3, and its lateral resolution was improved compared to the SD-OCT image shown in Figure 5a. The blue and red curves in Figure 5f show the lateral distribution of the structures within the yellow dashed boxes in Figure 5a,d, respectively. The result of Figure 5f indicates that the diffusion of the structure was reduced by approximately 2.4 times at a depth of approximately 5.7 Rayleigh ranges above the focus plane, which was consistent with that of the 2D image. Figure 5: Experiment results of the acinar cells of an orange. The images in (**a,b**) are results of SD-OCT and ISAM obtained by complete spectral data, respectively; (**c**) shows the image in which the selected A-scans were reconstructed, and (**d**) shows the reconstructed 2D image using 50% \(\times\) 50% data. The depth range within the green dashed box in (**a,b**) is the theoretical range of depth of focus (DOF). (**e**) Lateral distribution of the structures within the yellow dashed boxes in (**a,b**); (**f**) lateral distribution of the structures within the yellow dashed boxes in (**a,d**); (**g,h**) lateral distribution of the structures within the blue and purple dashed boxes in (**a,d**). obtained with 100% data shown in Figure 5e. The structures in the blue, purple, and pink dashed boxes are located at depths of 410 \(\upmu\)m (approximately 4.2 Rayleigh), 217 \(\upmu\)m (approximately 2.2 Rayleigh), and 41 \(\upmu\)m (approximately 0.4 Rayleigh) from the focal plane, respectively. The curves in Figure 5g and Figure 5h show the lateral distribution of the structures within the blue and purple dashed boxes in Figure 5a,d, respectively. The distribution of structures at the depth of 0.4 Rayleigh range is plotted in Figure 5h. Although the lateral widths of the structures at different depths for comparison in Figure 5f-h are not identical, it is still demonstrated that the dispersion of structures outside the Rayleigh range can be reduced to the level within the Rayleigh range using the CS-ISAM method. There is an issue that needs to be explained. For comparison, the range of the abscissa of Figure 5g,h was set to 300 \(\upmu\)m, but the portion without the signal was invalid. For a \(0.7\times 1.5\) mm orange image, the time to acquire spectral data volume was 2.1 and 0.8 s, respectively, at full sampling (70 depth scans and 512 spectral sampling points per depth scan) and 25% sampling rate (35 depth scans and 256 spectral sampling points per depth scan). Therefore, CS-ISAM is advantageous in terms of imaging speed, especially when imaging large moving objects. Figure 6 shows the imaging results for the onion tissue.