We first performed experiments to characterize the behavior of the scanner during M-mode scan, upon which to design the optimized scanning pattern. In experiments, we used a stationary cardboard as the sample. In this case, the complication for in vivo tissue such as tissue motion or cell swelling/shrink would be absent, facilitating the use of a correlation approach to characterize the OCT signals to achieve our purpose. The fast axis scanner was driven by a step waveform with 400 steps for one B-scan. In each step, A-scans were acquired, thus the total number of A-scans in each B-scan was 20,000. In the slow axis direction, we captured 200 B-frames to accomplish one 3-D scan covering an area of . For each B-scan, the absolute values of CD between the ’th and ()’th A-scans were calculated, where is the number of skipped A-scans. In this study, we selected , 3, and 9 to provide three ranges of velocities, corresponding to , , and , respectively, assuming that the refractive index of tissue is 1.35. Finally, CDs were averaged throughout the 3-D scan according to , which was the remainder of () divided by . The results are given in Fig. 1(b). We found that for the system used for this study, the minimal CD corresponds to for any , indicating the time point within each step when the scanner is most unstable. This is an important finding because it is contrary to the expected situation where we would expect the most unstable region is close to the beginning of the step edge. The unstable region being shifted to the second half of the step is most likely caused by the communication between the scanner, the computer, and the detection device for synchronized data acquisition. According to this finding, the system should only utilize the first half of the step to provide improved imaging of multirange velocities. Therefore, we designed the camera trigger to capture only the A-scans when is satisfied. In this case, when skipping A-scans within this set of A-scans, they would always meet the condition defined by [see bottom of Fig. 1(b), left region of vertical line]. Note that the scanner behavior is system dependent; thus, it is recommended that each system has to be individually optimized in order to use the step-scan to obtain variable velocity ranges.