Apple’s iPhone 12 Pro has a more powerful LiDAR scanner than last year’s iPhone 11 Pro. Apple describes the new LiDAR scanner in five ways on their website as follows:
LiDAR delivers up to 6x faster autofocus in low light
Night mode comes to both the Wide and Ultra-Wide cameras, and it’s better than ever at capturing incredible low-light shots. LiDAR makes Night mode portraits possible. And the Wide camera lets in 27 percent more light, for greater detail and sharper focus day or night.
LiDAR Scanner: AR at the speed of light
The LiDAR Scanner on iPhone 12 Pro measures how long it takes light to reflect back from objects, so it can create a depth map of any space you’re in. Because it’s ultrafast and accurate, AR apps can now transform a room into a realistic rainforest or show you exactly how a new sneaker will fit.
Even with a single small light source, LiDAR and our A14 Bionic can render every pattern and texture in the foreground along with realistic color throughout the room.
Apple Wins a Major LiDAR Related Patent
Yesterday the U.S. Patent and Trademark Office published Apple’s granted patent 10,823,955 titled “Grating-based spatial mode filter for laser scanning” that may shed some light on how Apple improved the iPhone 12 Pro’s LiDAR scanner. Apple’s granted patent describes adding “Volume Holographic Grating” (VHG) to their LiDAR scanning system.
Apple notes that their newly granted patent relates to a new compact scanning device what is used within a LiDAR-system. Apple’s next-gen LiDAR-system will use (or is using) what is known in the industry as a “Volume Holographic Grating,” abbreviated “VHG,” which provides a wavelength stabilization of lasers amongst other things.
According to Apple, there are a couple of issues regarding current standard optical architectures.
Apple states in their granted patent that “An optical scanner projects and scans a beam from a light source across a one- or two-dimensional angular space. In a case where the optical scanner is used in a LiDAR-system, the beam is projected to a target scene, and the beam reflected from the scene is received by the scanner and forwarded to a radiation detector adjacent to the light source. Optical scanners are commonly based on a combination of a laser light source and a single-axis or double-axis scanning mirror. Two different optical architectures are commonly used for these scanners:
#1. In the first architecture, the illuminating beam impinges on a scanning mirror from an off-axis direction (from a direction not along the central axis of the scan), and the mirror scans the beam across an angular range that is separated from the illuminating beam. This off-axis illumination forces the scanning mirror to work at large angles of reflection, leading to a highly distorted scan.
#2. In the second architecture, the illuminating beam is directed to the scanning mirror via a beamsplitter. The beamsplitter reflects a part of the beam toward the scanning mirror, which in turn scans the beam across the angular range, with a part of the scanned beam passing through the beamsplitter to a target scene, for example. The use of a beamsplitter enables illuminating the mirror on-axis (along the central axis of the scan), thus avoiding large scan angles and the concomitant distortion. However, this architecture suffers from the optical power loss inherent in the double-pass use of a partially transparent beamsplitter.
After outlining the current issues with typical LiDAR systems, Apple goes on to state that “Embodiments of the present invention that are described herein address these problems by providing a compact scanning device with on-axis illumination and a low optical power loss.
Apple’s patent FIGS. 1A-B below are schematic top and side views, respectively, of a new optical device. The controller #18 noted in 1B maps the distance to the target scene based on the round-trip time-of-flight of the pulses of light and the instantaneous angular position of the beam.
Click on image to Enlarge
2 X Apple LiDAR patent figs
Apple’s granted patent is a tough read unless you happen to be an optical engineer or are currently practicing a similar discipline. Of course, there will always be curious techies that love a challenge and they could check out the patent here.
Content retrieved from: https://www.patentlyapple.com/patently-apple/2020/11/apple-wins-a-patent-detailing-the-advancement-of-their-lidar-scanning-system-that-could-be-included-in-the-iphone-12-pro.html.