Mobile photography has transformed smartphones into powerful imaging tools, making camera performance a critical factor for consumers. Modern smartphones now incorporate multi-lens systems, including wide, ultra-wide, and telephoto options, enabling high-quality imaging and enhanced versatility.1
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One of the key challenges in smartphone camera design is integrating advanced zoom capabilities without increasing device thickness. Periscopic lens technology addresses this limitation by utilizing a folded optical path with mirrors or prisms, allowing for extended focal lengths while maintaining a slim profile.2
In 2019, Apple Inc. secured a U.S. patent for a periscope-style prime lens system, featuring a 4.5 mm diagonal sensor, an F/1.6 aperture, a 36.8 ° full field of view, and a lens depth of 6.5 mm. The patent indicates that smartphone integration remains feasible only for lens modules with a depth under 6.5 mm, reinforcing the need for compact optical innovations.3
Periscopic Lenses: Structure and Function
A periscope lens consists of multiple optical elements arranged within a long, narrow tube, with two 45 ° angled lenses positioned at each end. The first lens captures incoming light and reflects it through the lens system, ultimately directing it to the second 45 ° lens, which maintains a straight-line optical path.4
Periscopic lenses function by using a right-angle prism to redirect incoming light by 90 ° into a zoom lens system. This design allows for compact integration into slim devices like smartphones. The prism bends light horizontally, enabling longer focal lengths while preserving a thin profile. The optical path is defined by parameters such as prism thickness, surface aperture, and half-field angle, which must remain within the constraints of the device’s thickness.1,5
As light enters the zoom lens system through an entrance pupil, its path is tracked by reference rays to ensure precise focusing. The focal length and field of view adjust dynamically across zoom positions (wide-angle, middle, and telephoto), while the F-number (ratio of focal length to entrance pupil diameter) regulates light intake and depth of field.
The final image is formed on the sensor, with optimized optical performance minimizing aberrations such as lateral color distortion, ensuring sharp image resolution across the zoom range. This design balances compactness and image quality, making periscopic lenses a key innovation in modern smartphone photography.1,2
Periscopic Lenses in Smartphones
Periscopic lenses have transformed smartphone photography by enabling high-magnification optical zoom in compact devices. Unlike traditional zoom lenses, which require substantial vertical space, periscopic lenses utilize a folded optical path, allowing smartphones to achieve 3x to 10x optical zoom while maintaining a slim profile.2,6
One notable innovation comes from Hou et al., who introduced a periscope zoom camera module incorporating Alvarez freeform elements. The compact system, measuring 25 mm × 25 mm × 6 mm, achieved 3X optical magnification by laterally shifting two pairs of Alvarez lenses. This design enabled smooth zoom functionality while preserving a thin form factor, making it suitable for smartphone integration.7
Several flagship smartphones have adopted periscopic lenses to enhance zoom capabilities. The Huawei P30 Pro, released in 2019, pioneered periscope camera technology in smartphones, featuring an 8MP periscope telephoto lens capable of 5x optical zoom. Paired with advanced computational photography algorithms, this setup delivered sharp, detailed zoom images.
Samsung later introduced periscope lenses in its Galaxy S20 Ultra, which featured a 48MP periscope lens capable of up to 10x hybrid zoom, supported by Optical Image Stabilization (OIS) to ensure stable, zoomed-in shots. Since then, periscopic lenses have become a standard feature in Samsung’s Galaxy ‘Ultra’ flagship models.
Samsung Galaxy S20 Ultra 100X Zoom Camera Reviewed by a Private Eye | WSJ
More recently, the Vivo X100 Ultra introduced a 200MP periscope camera, incorporating a 1/1.4-inch ISOCELL HP9 sensor developed in collaboration with Samsung. This lens offers 3.7x optical zoom and, due to its large sensor size, captures more light, producing highly detailed and clear images. The same advanced sensor is also utilized in the Vivo X200 Pro.
Are Periscopic Lenses Worth It? Pros and Cons Explained
Periscopic lenses provide high-magnification optical zoom (e.g., 3x, 5x, or 10x) without requiring a bulky camera module, allowing users to capture distant subjects with exceptional clarity.1 By folding the optical path horizontally, these lenses reduce the overall thickness of the camera system, ensuring that smartphones remain slim and portable.
Image quality is also significantly improved due to the use of aspheric lenses, which are incorporated into periscopic lens systems to correct optical aberrations, enhance sharpness, and reduce distortion. In traditional zoom lenses, spherical elements can introduce distortions at high magnifications. A 10x periscope zoom lens, for example, can achieve a modulation transfer function (MTF) of up to 74.3 %, delivering high-resolution images even at maximum zoom.1
However, integrating periscopic lenses into smartphones presents several engineering challenges. Precise alignment of prisms, mirrors, and lenses is required, as even slight misalignments can degrade image quality. Tolerance analysis is essential during manufacturing to maintain optical performance.2
Additionally, the production of aspheric lenses, a key component of periscopic systems, involves advanced techniques like Precision Glass Molding (PGM). While PGM is more cost-effective than traditional methods, it remains more expensive than spherical lens manufacturing.2
Thermal and mechanical stability is another concern. The compact design of periscopic lenses leaves minimal room for error, requiring high-performance materials and rigorous testing to ensure durability under varying conditions.2
Despite these challenges, periscopic lenses continue to push the boundaries of smartphone photography, delivering high-quality zoom capabilities without compromising device design.
For more information on smartphone camera technology and optical innovations, explore these resources:
References and Further Readings
1. Sun, W.-S.; Liu, Y.-H.; Tien, C.-L. Optical Design of a Miniaturized 10× Periscope Zoom Lens for Smartphones. Micromachines 2023, 14, 1272. https://www.mdpi.com/2072-666X/14/6/1272
2. Sun, W.-S.; Tien, C.-L.; Liu, Y.-H., Optical Design for the Lens Depth of a Periscope-Type 3× Zoom Lens with 8-Megapixel Mobile Phone. Optical and Quantum Electronics 2020, 52, 1-16. https://link.springer.com/article/10.1007/s11082-020-2256-3
3. Yao, Y.; Shinohara, Y., Folded Lens System with Five Refractive Lenses. Google Patents: 2019. https://patents.google.com/patent/US10437022B2/en
4. Peli, E.; Vargas-Martin, F.; Kurukuti, N. M.; Jung, J.-H., Multi-Periscopic Prism Device for Field Expansion. Biomedical Optics Express 2020, 11, 4872. https://opg.optica.org/boe/fulltext.cfm?uri=boe-11-9-4872&id=434232
5. Haltovsky, A.; Shemar, A.; Schwarz, A.; Gur, E. In The Refractive Periscope–a Novel Concept, IOP Conference Series: Earth and Environmental Science, IOP Publishing: 2021; p 012019. https://iopscience.iop.org/article/10.1088/1755-1315/897/1/012019
6. Blahnik, V.; Schindelbeck, O., Smartphone Imaging Technology and Its Applications. Advanced Optical Technologies 2021, 10, 145-232. https://www.degruyter.com/document/doi/10.1515/aot-2021-0023/html?lang=en&srsltid=AfmBOoqhgty9wqZ7n2BJdjX111CLKi9XKDBFFiayQEfyX5erbsubvPKL
7. Hou, C.; Ren, Y.; Tan, Y.; Xin, Q.; Zang, Y., Compact Optical Zoom Camera Module Based on Alvarez Elements. Optical Engineering 2020, 59, 025104-025104. https://ui.adsabs.harvard.edu/abs/2020OptEn..59b5104H/abstract
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