David Hall invented modern three-dimensional lidar more than a decade ago for use in the DARPA Grand Challenge competitions. His company, Velodyne, has dominated the market for self-driving car lidar ever since. Last year, Velodyne opened a factory that it said had the capacity to produce a million lidar units in 2018—far more than any other maker of high-end lidars.

Now Velodyne is starting to see some serious competition. Last week, lidar startup Luminar announced that it was beginning volume production of its own lidar units. The company expects to produce 5,000 units per quarter by the end of 2018.

Meanwhile, Israeli startup Innoviz is also getting ready to manufacture its InnovizPro lidar in significant volume. The company declined to give Ars exact production numbers, only telling us it has orders for thousands of units. Innoviz believes it can scale up manufacturing quickly to satisfy that demand.

Obviously, making lidar a mainstream automotive technology will require millions of lidar units—not just thousands. At this point, Velodyne's rivals are still focused primarily on distributing units to companies for evaluation, testing, and development. The ultimate goal is to convince customers to put in much larger orders for lidar sensors a year or two down the road for use in shipping products.

Both Velodyne and Innoviz say they expect their lidar units to cost hundreds rather than thousands of dollars in the long run. But the companies are keeping the exact specs and prices of their products secret, making it hard to figure out how far they are from this goal or who really has the lead.

The competition: Building a different kind of lidar

To build his original lidar, David Hall mounted 64 lasers on a spinning gimbal that rotated several times per second. Since then, Velodyne has created a number of different lidar models that operate on the same basic principle. Today, Velodyne has models that use 16, 32, 64, and 128 lasers.

Luminar and Innoviz take a dramatically different approach from Velodyne's. Both sell lidars with a single laser that scans across the landscape with the help of a tiny moving mirror. There's an obvious cost advantage to using just one laser, and this approach can give more flexibility about the vertical resolution and scanning frequency of a lidar unit.

But a big downside of this design is that it can't provide 360 degree coverage. Luminar says it can cover 120 degrees horizontally. In practice, this means that a vehicle needs four Luminar units to provide the same 360-degree coverage as a single Velodyne unit.

Velodyne is also producing a solid-state lidar called the Velarray. But based on conversations with the company, spinning lidars continue to be their main focus.