For 25 years, the field of robotics has been bedeviled by a fundamental problem: If a robot is to move through the world, it needs to be able to create a map of its environment and understand its place within it. Roboticists have developed tools to accomplish this task, known as simultaneous localization and mapping, or SLAM. But the sensors required to build that map have traditionally been either expensive and bulky or cheap and inaccurate. Laser arrays cost a few thousand...