Apple has filed for a patent (number 20220229210) for a “microlens with tailored sag profile.” It involves lens for the rumored “Apple Glasses,” an augmented reality/virtual reality head-mounted display.
About the patent filing
What’s a sag, you ask, In optics, the term “sag” (short for sagitta) is a measure of the shape of an optical element. (Traditionally, the sag expresses the amount of material to be removed from a transparent blank in order to create a given spherical or aspheric lens form.) In other words, the sag thus specifies how a lens will modify a transmitted beam of optical radiation by determining the direction of rays refracted at its surface (or alternatively the phase that the beam accumulates).
In the patent filing, Apple notes that, generally speaking, any sag can be manufactured. And the tech giant apparently wats to use this to make augmented reality and virtual reality as realistic as possible on its device.
About Apple Glasses
When it comes to Apple Glasses, the rumors are abundant. Such a device will arrive in mid-to-late 2023. Or maybe 2024. It will be a head-mounted display. Or may have a design like “normal” glasses. Or it may be eventually be available in both. The Apple Glasses may or may not have to be tethered to an iPhone to work. Other rumors say that Apple Glasses could have a custom-build Apple chip and a dedicated operating system dubbed “rOS” for “reality operating system.”
Summary of the patent filing
Here’s Apple’s abstract of the patent filing: “An optical device includes a first array of emitters disposed on a substrate and configured to emit respective beams of optical radiation in a direction perpendicular to the substrate. A second array of microlenses is positioned on the substrate in alignment with the respective beams of the emitters, having respective sag profiles that vary over an area of the substrate.
“The second array includes at least first microlenses in a central region of the substrate and second microlenses in a peripheral region of the substrate, such that the first microlenses have respective first focal powers, while the second microlenses have respective second focal powers, which are less than the first focal powers.”
