Apple has just been approved for a patent describing a "Self-Mixing Interferometry-Based Gesture Input System Including a Wearable or Handheld Device." In slightly more layman's terms, Apple describes its concept of a variety of "handheld devices"—one of which is "a wearable device such as a finger ring." The patent explains how this ring would be fitted with a set of one or more SMI sensors, and a processor.
SMI technology is a kind of optical echocolation, where a laser emits a beam which hits the first object or surface in its path, and is reflected back into the laser sensor. This can be used to gain digital imagery and information about the surroundings of a gadget fitted with an SMI sensor. Apple says these SMI sensors will do just that: emit beams in different directions to extract "information about a relationship between the [ring's] housing and a second surface." It is not clear what the second surface is, but some of the sketches show the wearer holding an Apple Pencil, as well as wearing two interacting rings at once.
If only one SMI sensor is included, Apple says, the ring will be able to determine the motions of a user along the emitted beam's axis. If there are two sensors, the ring will read motions in a two-dimensional plane. With three or more SMI sensors, the ring would be able to place its wearer's movements in a complete 3D environment.
With 3D mapping of the environment, a ring with three SMI sensors opens all kinds of potential for versatile use. An ability to follow a moving finger or hand through space could allow you to write, draw, or execute commands on other Apple gadgets simply by waving your hand in the air.
Back in 2019, Apple filed for a "wearable electronic ring" which was aimed at controlling other Apple devices without having to take them out of your pocket. The concept featured a touchscreen atop the ring, voice command, and hand gesture control, among other things. However, that idea didn't seem to go anywhere, since we heard nothing more about it—and this patent now seems to cater to different purposes and use an entire technology altogether.
It seems logical to assume that like Apple's last ring concept, this Apple ring might be able to relate back to other Apple devices (after all, the Apple Pencil is shown in the sketches), but Apple does not provide any information in the patent about this yet. Instead, it focuses more on the gadget's processor and SMI sensors themselves, and the possibility of implementing alternative housings to the invention—not necessarily a ring shape.