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'''Pancake lenses''' (also known as '''pancake optics''' or '''folded optics''') are a type of compact [[catadioptric system|catadioptric]] optical system used in [[virtual reality]] (VR) and [[augmented reality]] (AR) headsets that employs polarization-based light path folding to dramatically reduce the physical distance between the display and the lens.<ref name="Wiley1978">LaRussa, Joseph A.; Gill, Arthur T. (1978). "The Holographic Pancake Window". ''SPIE Proceedings''. '''0162''': 120-129. [https://www.spiedigitallibrary.org/conference-proceedings-of-spie/0162/120/The-Holographic-Pancake-Window-/10.1117/12.956898.short]. Retrieved 2025-10-26.</ref><ref name="Trioptics">{{cite web |url=https://www.trioptics.com/applications/alignment-and-testing-of-lens-systems/pancake-optics |title=Measurement solutions for pancake optics |publisher=TRIOPTICS |access-date=2025-10-26}}</ref> This technology enables VR/AR headsets to achieve 40-66% thinner profiles compared to traditional [[Fresnel lens]] designs while delivering superior edge-to-edge clarity and eliminating characteristic "god ray" artifacts.<ref name="Avantier">{{cite web |url=https://avantierinc.com/solutions/custom-optics/pancake-lenses-for-vr-optical-systems/ |title=Pancake Lenses for VR Optical Systems |publisher=Avantier Inc. |access-date=2025-10-26}}</ref><ref name="ExpandReality">{{cite web |url=https://landing.expandreality.io/pancake-vs.-fresnel-lenses-in-vr-headsets-advanced-optics-for-vr |title=Pancake vs. Fresnel Lenses in VR Headsets: Advanced Optics for VR |publisher=Expand Reality |date=2024-09-05 |access-date=2025-10-26}}</ref>
'''Pancake lenses''' (also known as '''pancake optics''' or '''folded optics''') are a type of compact [[catadioptric system|catadioptric]] optical system used in [[virtual reality]] (VR) and [[augmented reality]] (AR) headsets that employs polarization-based light path folding to dramatically reduce the physical distance between the display and the lens.<ref name="Wiley1978">LaRussa, Joseph A.; Gill, Arthur T. (1978). "The Holographic Pancake Window". ''SPIE Proceedings''. '''0162''': 120-129. [https://www.spiedigitallibrary.org/conference-proceedings-of-spie/0162/120/The-Holographic-Pancake-Window-/10.1117/12.956898.short]. Retrieved 2025-10-26.</ref><ref name="Trioptics">{{cite web |url=https://www.trioptics.com/applications/alignment-and-testing-of-lens-systems/pancake-optics |title=Measurement solutions for pancake optics |publisher=TRIOPTICS |access-date=2025-10-26}}</ref> This technology enables VR/AR headsets to achieve 40-66% thinner profiles compared to traditional [[Fresnel lens]] designs while delivering superior edge-to-edge clarity and eliminating characteristic "god ray" artifacts.<ref name="Avantier">{{cite web |url=https://avantierinc.com/solutions/custom-optics/pancake-lenses-for-vr-optical-systems/ |title=Pancake Lenses for VR Optical Systems |publisher=Avantier Inc. |access-date=2025-10-26}}</ref><ref name="ExpandReality">{{cite web |url=https://landing.expandreality.io/pancake-vs.-fresnel-lenses-in-vr-headsets-advanced-optics-for-vr |title=Pancake vs. Fresnel Lenses in VR Headsets: Advanced Optics for VR |publisher=Expand Reality |date=2024-09-05 |access-date=2025-10-26}}</ref>


The core innovation involves manipulating light [[polarization]] states to bounce photons multiple times between lens elements before reaching the user's eye, effectively "folding" the optical path within a compact module typically just 17-21mm thick.<ref name="RoadToVR">{{cite web |url=https://www.roadtovr.com/pico-4-announcement-release-date-specs-vs-quest-2/ |title=Pico 4 Announced with October Launch |publisher=Road to VR |date=2022-09-22 |access-date=2025-10-26}}</ref> However, this design suffers from extremely low light efficiency—typically transmitting only 10-25% of display light to the eye—requiring exceptionally bright displays and creating significant power consumption challenges.<ref name="Pimax">{{cite web |url=https://pimax.com/blogs/blogs/aspheric-vs-pancake-vr-lenses-and-why-glass |title=Aspheric vs. Pancake VR Lenses, and why glass? |publisher=Pimax |date=2024-05-11 |access-date=2025-10-26}}</ref><ref name="OpticaGhost">"Analysis of ghost images in a pancake virtual reality system". ''Optics Express''. '''32''' (10): 17211-17226. 2024. [https://opg.optica.org/oe/abstract.cfm?uri=oe-32-10-17211]. Retrieved 2025-10-26.</ref>
The core innovation involves manipulating light [[polarization]] states to bounce photons multiple times between lens elements before reaching the user's eye, effectively "folding" the optical path within a compact module typically just 17-21mm thick.<ref name="RoadToVR">{{cite web |url=https://www.roadtovr.com/pico-4-announcement-release-date-specs-vs-quest-2/ |title=Pico 4 Announced with October Launch |publisher=Road to VR |date=2022-09-22 |access-date=2025-10-26}}</ref> However, this design suffers from extremely low light efficiency, typically transmitting only 10-25% of display light to the eye, requiring exceptionally bright displays and creating significant power consumption challenges.<ref name="Pimax">{{cite web |url=https://pimax.com/blogs/blogs/aspheric-vs-pancake-vr-lenses-and-why-glass |title=Aspheric vs. Pancake VR Lenses, and why glass? |publisher=Pimax |date=2024-05-11 |access-date=2025-10-26}}</ref><ref name="OpticaGhost">"Analysis of ghost images in a pancake virtual reality system". ''Optics Express''. '''32''' (10): 17211-17226. 2024. [https://opg.optica.org/oe/abstract.cfm?uri=oe-32-10-17211]. Retrieved 2025-10-26.</ref>


Since entering the consumer market with the [[Huawei VR Glass]] in 2019, pancake lenses have rapidly become the standard for premium VR/MR headsets.<ref name="UploadVR">{{cite web |url=https://uploadvr.com/huawei-vr-glass-6dof-announced/ |title=Huawei VR Glass 6DOF announced |publisher=UploadVR |date=2019-12-19 |access-date=2025-10-26}}</ref> Major implementations include the [[Meta Quest Pro]] (2022), [[Meta Quest 3]] (2023), [[Apple Vision Pro]] (2024), and [[Pico 4]] (2022), marking a pivotal industry shift toward prioritizing comfortable, lightweight designs over optical efficiency.<ref name="InsightMedia">{{cite web |url=https://www.insightmedia.info/kopin-all-plastic-pancake-optics-for-vr-ar-mr/ |title=Kopin All-Plastic Pancake Optics for VR/AR/MR |publisher=Insight Media |date=2021 |access-date=2025-10-26}}</ref>
Since entering the consumer market with the [[Huawei VR Glass]] in 2019, pancake lenses have rapidly become the standard for premium VR/MR headsets.<ref name="UploadVR">{{cite web |url=https://uploadvr.com/huawei-vr-glass-6dof-announced/ |title=Huawei VR Glass 6DOF announced |publisher=UploadVR |date=2019-12-19 |access-date=2025-10-26}}</ref> Major implementations include the [[Meta Quest Pro]] (2022), [[Meta Quest 3]] (2023), [[Apple Vision Pro]] (2024), and [[Pico 4]] (2022), marking a pivotal industry shift toward prioritizing comfortable, lightweight designs over optical efficiency.<ref name="InsightMedia">{{cite web |url=https://www.insightmedia.info/kopin-all-plastic-pancake-optics-for-vr-ar-mr/ |title=Kopin All-Plastic Pancake Optics for VR/AR/MR |publisher=Insight Media |date=2021 |access-date=2025-10-26}}</ref>