Month: February 2022

Enlarge / The small light-absorbing portions (labeled 12 in this diagram) are key to Sony’s solution to the “god ray” problem. (credit: Sony / USPTO)

If you’ve spent any significant amount of time in virtual reality, you’ve probably encountered issues with “god rays,” a specific type of lens flare that looks a bit like a sunbeam shining through the clouds and right on your eye. Now, a recently unearthed patent from Sony suggests the PlayStation VR maker may have solved that problem for its upcoming PlayStation VR2 headset.

An illustration comparing traditional curved lenses (left) and flatter Fresnel lenses (right). (credit: Edmund Optics)

The presence of god rays (or crepuscular rays, to use a more technical and less religious term) in virtual reality is an artifact from the use of Fresnel lenses in most headsets. Unlike a traditional dome-shaped lens, a Fresnel lens uses precisely angled concentric grooves on the surface of a clear flat panel to focus light on a specific point.

This lets Fresnel lenses operate at a much smaller focal length and with a thinner and lighter profile than a traditional lens, making them ideal for virtual reality headsets. But the downside is that the edges of those concentric grooves sometimes throw a ray of light sideways rather than focusing it, which can show up as a crepuscular ray when it hits your eye.

Enlarge / The iPhone XS, the oldest iPhone that will support Tap to Pay on iPhone. (credit: Samuel Axon)

Today, Apple announced a limited new feature coming to iOS. With “Tap to Pay on iPhone,” merchants and vendors will be able to accept contactless payments from customers at point-of-sale using just an app on the iPhone. No additional hardware will be necessary.

Up to this point, point-of-sale apps like Stripe have had to use additional hardware that connects to the iPhone either wirelessly or over the Lightning or headphone port. Now, no additional hardware will be needed—but developers will have to build this functionality into their apps using the tools Apple provides.

At least for now, Tap to Pay will only work on apps from Apple’s participant partners. Right now, that means Stripe, a giant in the mobile point-of-sale industry. More partners are coming later, Apple says.

Enlarge / Two formerly paralyzed individuals go for a stroll in Lausanne, Switzerland. (credit: EPFL)

Spinal cord injuries are life-altering, as they prevent the transmission of nerve impulses past the point of injury. That means no sensory inputs make it to the brain, and no signals from the brain make it to the muscles normally controlled by the brain. But improvements in our understanding of neurobiology have raised the hope that we can eventually restore some control over paralyzed limbs.

Some of these efforts focus purely on nerve cells, attempting to get them to grow through the damage at the site of injury and restore a functional spinal cord. Others attempt to use electronics to bypass the injury entirely. Today, there was very good news for the electronics-focused effort: researchers have designed a spinal implant that can control the leg muscles of paralyzed individuals, allowing them to walk with assistance within hours of the implant being activated.

Skipping the brain

Much of the spinal cord is composed of long extensions made by nerve cells, termed axons. These axons allow nerve impulses to travel long distances, which is necessary for information to travel back and forth to the brain. Sensory inputs, like pain in your elbow or tickling of your feet, ride axons up the spinal cord into the brain. The brain in turn sends signals back down the spinal cord, controlling your breathing or moving your arms.

Enlarge / The Raspberry Pi 4. (credit: Raspberry Pi Foundation)

Setting up a Raspberry Pi board has always required a second computer, which is used to flash your operating system of choice to an SD card so your Pi can boot. But the Pi Foundation is working on a new version of its bootloader that could connect an OS-less Pi board directly to the Internet, allowing it to download and install the official Raspberry Pi OS to a blank SD card without requiring another computer.

To test the networked booting feature, you’ll need to use the Pi Imager on a separate computer to copy an updater for the bootloader over to an SD card—Pi firmware updates are normally installed along with new OS updates rather than separately, but since this is still in testing, it requires extra steps.

Once it’s installed, there are a number of conditions that have to be met for network booting to work. It only works on Pi 4 boards (and Pi 4-derived devices, like the Pi 400 computer) that have both a keyboard and an Ethernet cable connected. If you already have an SD card or USB drive with a bootable OS connected, the Pi will boot from those as it normally does so it doesn’t slow down the regular boot process. And you’ll be limited to the OS image selection in the official Pi imager, though this covers a wide range of popular distributions, including Ubuntu, LibreELEC, a couple of retro-gaming emulation OSes, and Homebridge. For other OSes, downloading the image on a separate PC and installing it to an SD card manually is still the best way to go.