Pancake Lens VR Headsets

Pancake Lens VR Headsets

Pancake lenses eliminate ghosting but have low light efficiency, which requires bright displays that drain the battery faster and create heat in the headset. Also, they produce “god rays”, distracting to the user.

Kopin’s all-plastic pancake lens is a significant breakthrough and can enable much more compact VR headset designs. It delivers superior image quality, smaller size, lighter weight, and lower cost than currently available.

Improved visual fidelity

Pancake lenses are a relatively new type of VR lens that has been shown to provide improved visual fidelity. They use a combination of polarizers, quarter-wave plates and reflective surfaces to fold the optical path. This results in a more minor assembly that is lighter and more compact than conventional Fresnel lens designs. These lenses also help eliminate issues such as god rays and ghosting associated with traditional headsets.

Unlike Fresnel lenses, pancake lenses do not require a separate layer of glass to correct for field curvature. They have a lower coefficient of refraction, which means they can be made thinner and lighter. This makes them more comfortable to wear. In addition, they are more resistant to damage from UV-C rays.

In some embodiments, the pancake lens includes a volume Bragg grating (VBG) to increase optical efficiency between the peripheral display and the eye box. In addition, the VBG can reduce the amount of light that is reflected off the peripheral display. This is especially useful in headsets with large FOVs, which can cause light scattering and glare.

The pancake lens block 102 has one or more coupling surfaces 104 and 106 that are shaped to mitigate field curvature. For example, the coupling surfaces can be shaped to be spherically concave or spherically convex, a rotationally symmetric sphere, a freeform shape, or another type of shape that minimizes field curvature.

Another advantage of the pancake lens is its ability to reduce glare from external sources, such as streetlights and headlights. This is because the pancake lens blocks out more light than a standard filter and is more effective at correcting for distortion. In addition, the pancake lens can be positioned closer to the display than traditional lenses.

While the pancake lens does have a few drawbacks, it is still an excellent option for VR headsets. The main drawbacks are its limited FOV and lower light efficiency than Fresnel lenses. This means that it needs to be paired with brighter displays. This may lead to faster battery drainage and more heat, which can be uncomfortable for long gaming sessions. However, these drawbacks can be overcome with some minor design tweaks and improvements.

Resilient to UV-C disinfection

The UV light emitted by the sun is made up of four bands: UVa (315 to 400 nm), UVb (285 to 315 nm), UVc (200 to 280 nm) and UVv (10-200 nm). UVc is the most effective at inactivating microorganisms and is the band used for disinfection. While avoiding exposure to any UV radiation is essential, it is not always possible in a controlled environment. For this reason, virtual reality systems must be designed to be resilient to the energetic onslaught of UV-C.

The monolithic pancake lens block 102 is shaped to mitigate field curvature, which can reduce contrast for images displayed on the electronic display. One or more monolithic pancake lens block surfaces may be shaped to have a spherical surface profile, a portion of a sphere, a freeform shape or other suitable shape to correct for field curvature.

One way this is accomplished is by coupling a front optical element to a back optical element with a curved quarter waveplate retarder. The curved QWP retarder allows the monolithic pancake lens block to have a larger FOV on the x-axis than on the y-axis, which is beneficial for visual comfort. The curved QWP also helps to mitigate parasitic reflections and leakage between the front and back optical elements.

The curved QWP in the monolithic pancake lens block is coupled to a reflective polarizer surface 142 and a mirrored surface 132. The curved surface of the QWP matches the shape of the reflective polarizer and mirrored surfaces, eliminating air gaps between the two surfaces and, therefore, reducing parasitic reflections. This helps to improve contrast and reduce pupil swim.

The curved QWP in the monolithic pancake lens block also helps suppress stray light and increase the intended light throughput, which can help improve contrast. This is especially important because achieving high-resolution imagery on a display with flat, non-curved optical elements can be difficult. This is why Meta (aka Facebook) and Apple have used a curved QWP in their latest LC lenses.

Lightweight and compact

The current VR headsets are bulky and clunky. This is due to the optical design that uses thick-fresnel lenses to magnify a smartphone-sized display, sometimes split in two. This requires a large gap between the display and the lens, which adds to the headset’s overall size. The latest breakthrough in pancake lens technology could change this. The all-plastic pancake optics from Kopin are lighter and smaller than anything currently on the market and offer superior image performance.

The Kopin all-plastic pancake lens block 102 comprises front first and back second surfaces 104, 106. The front surface 104 is curved, forming coupling surfaces 111 and 113 to accommodate the planar hybrid film 320. The curved shapes of the front and back surfaces also have a similar centre of curvature that increases intended throughput, suppresses stray light, and improves contrast.

One of the biggest barriers to compacting VR headsets is the lens material, which limits how much light can pass through. The all-plastic pancake lens from Kopin uses a special plastic with negligible birefringence, which allows it to pass more light than any other plastic lens. It also has a patented aspherical optical lens design that provides excellent image quality and uses a novel processing method to preserve this high-quality image.

Unlike other VR headsets, which use a series of mirrors to split light into two images, the all-plastic pancake lens blocks 102 from Kopin incorporate a hybrid film that combines a traditional polarizer and a half-mirror. This allows the polarizer to split the incoming light into two images for better contrast and more even brightness across the display. It also allows the hybrid polarizer to filter out any stray light that might get into the device.

The all-plastic pancake lens from Kopin is ideal for future VR headsets that look more like regular glasses than the shoeboxes we wear today. The all-plastic pancake lens block 102 is compatible with Kopin’s flagship Lightning display for VR, a 1.3″ 2.6K x 2.6K OLED microdisplay that offers retina resolution and 10-bit HDR. It will enable a compact display architecture for VR headsets that are thinner, lighter, and easier to hold onto.

Better battery life

Pancake lens VR headsets have a more compact and lightweight design. The lenses are also a lot less sensitive to stray light. This helps with the display’s overall performance and makes the VR experience more comfortable for the user. Pancake lenses are a great way to improve a VR headset’s quality and battery life.

While the pancake lens has many benefits, it does have some drawbacks. The lens is polycarbonate, which is optically less transparent than glass. This means the lenses block significant light from reaching the display. This can lead to a low brightness and a pixelated image. This can be overcome by using a higher-power display, which raises the headset’s cost.

A solution to this problem is to use a hybrid film. The hybrid film can be inserted between the coupling surfaces of the front and back optical elements. The film can increase the optical efficiency by reducing stray light and allowing the display to operate at a lower power level. This results in a significantly longer battery life for the device.

Another problem with pancake lenses is that they are prone to ghost images. These distorted and blurry images appear on the display while a user moves their head. They can be a real nuisance, but the good news is that there is an easy fix for this problem. A new technology that uses pancake lenses to solve this issue is called “P95.” The technology eliminates the ghosting and glare while being more compact and lighter than other headsets.

The pancake lens is a huge step forward in VR headsets, but it is important to remember that the quality of a VR experience depends on many more factors than just the lens type. The most important factor is the display. This is why it is important to do your research before making a purchase. The best VR headsets will have high-resolution displays paired with powerful processors to deliver an immersive and enjoyable virtual reality experience.