Two lasers are used (but not simultaneously) in conjunction with a dual-scan scheme to overcome shadowing at overhangs, edges of steep holes, and the like. As depicted in the lower part of Figure 1, a surface is scanned twice: from left to right and from right to left. During the scan toward the right, the left laser is used; during the scan toward the left, the right laser is used. Both lasers illuminate common areas (typically, a central area at the bottom of a hole), and each laser illuminates an edge area that may be shaded from the other laser. Surface points in the hole that may be shaded from the left laser during the rightward scan are illuminated by the right laser during the leftward scan, and vice versa.
Figure 2 is a block diagram of the electronic system of the instrument. The system includes an onboard processor, plus an external personal computer (PC) for further processing of the acquired data and displaying resulting depth maps. The processor is capable of generating 3D data in real time, eliminating the need for both onboard memory and post-processing to generate 3D data. The 3D data output of the onboard processor is sent to the PC via a high-speed serial data-communication link. By reducing the computational burden on the PC, onboard preprocessing enables the PC to create and display 3D images in real time during scanning.
This work was done by Joseph Lavelle and Stefan Schuet of Ames Research Center.
This invention is owned by NASA and a patent application has been filed. Inquiries concerning rights for the commercial use of this invention should be addressed to the Ames Technology Partnerships Division at (650) 604-2954. Refer to ARC-14652-1.