How Are Camera Lenses Made?

By Owais AliReviewed by Lexie CornerApr 9 2025

Have you ever wondered how the lenses in your smartphone or DSLR are made?

This article provides an overview of camera lenses, including their design, manufacturing, and assembly processes, as well as recent advancements in lens production techniques.

Image Credit: Matveev Aleksandr/Shutterstock.com

What Is a Camera Lens?

A camera lens comprises multiple shaped glass elements housed within a cylindrical body. Its primary role is gathering and directing light onto a camera’s image sensor or film to produce a clear, focused image.

The lens regulates light intensity through an adjustable aperture, formed by a diaphragm with overlapping blades. Exposure is controlled by f-stop settings.

Focal length defines the angle of view: shorter focal lengths produce wider scenes, while longer ones provide narrower, zoomed-in views. Aperture size also affects depth of field (DoF); a larger aperture creates a shallow focus, while a smaller one increases sharpness across a greater range.

These optical characteristics work together to define image clarity, composition, and depth.¹

How Are Camera Lenses Designed?

Lens design requires precise calculation of surface curvatures, element thicknesses, airspaces, and material properties. The objective is to ensure all light rays from an object point converge at the image point without distortion. This process involves meticulous correction of optical aberrations, including spherical aberration, coma, astigmatism, and chromatic aberration.

Designers work within the principles of geometrical optics, treating light as rays that travel in straight lines through uniform media and refract at material interfaces according to Snell's law. This assumption simplifies the design process and allows light to be modeled as rays. To focus light effectively, lenses are typically curved to increase the angle of incidence and bring rays to a common focal point. However, shorter focal lengths require steeper curvatures, which introduce manufacturing challenges and more pronounced aberrations.

A common approach to correcting these issues involves changing the lens shape or replacing simple single-lens elements with more complex multi-element designs such as doublets, triplets, or symmetrical systems. These configurations help balance the optical powers of individual elements and reduce aberrations like distortion, astigmatism, and field curvature.^2-4

Material Selection

Glass remains the primary material for camera lenses due to its high refractive index, low dispersion, and resistance to environmental degradation and scratching. Historically, optical glasses were classified into crown and flint types.

However, 20^th-century advancements introduced fluoride, fluorosilicate, and rare earth–doped glasses (such as lanthanum-based formulations) to reduce chromatic aberration and improve design flexibility.

For example, N-FK5 provides extra-low dispersion, N-BK7 is a standard optical glass, and high-index types like N-SF2 and N-LAF7 are selected for more demanding imaging requirements.

Plastics such as acrylic and optical resins are also used, especially for molded or hybrid aspherical elements. These materials allow for the creation of complex geometries that improve image quality and simplify assembly. However, due to their susceptibility to surface damage, plastic elements are typically used only in interior lens components.^5,6

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The Manufacturing Process

Material Processing

The process begins with selecting and mixing raw materials to eliminate impurities such as iron, preserving optical clarity. This mixture is melted in crucibles at temperatures above 1500 °C, with continuous stirring to ensure uniform composition.

After solidification, the glass is crushed and remelted at around 1300 °C in a continuous fusion system for further homogenization. The molten glass is then poured into molds and cooled gradually to minimize air bubbles and inconsistencies.

Initial Glass Preparation

Once cooled, the glass sheets are ground to near-final thickness, tested for defects, and reprocessed into lens blanks through repeated grinding and heat pressing. These blanks are then annealed at 500 °C to eliminate residual stress and enhance structural consistency.

Lens Machining

The blanks undergo rough grinding with diamond grindstones to shape the lens curvature. The process moves from coarse to fine abrasives, achieving dimensions within 10–20 microns of specification. Grinding forces are carefully controlled to avoid surface damage.

Fine Grinding and Polishing

Fine grinding and polishing refine surface geometry, using cast iron tools and cerium oxide slurry to achieve sub-micron smoothness. This step is particularly important for large lenses with shallow curvature, which require individual attention.

Cleaning and Quality Inspection

After polishing, lenses are cleaned with ultrasonic methods to remove any remaining residues. They are then inspected using laser-based systems to assess dimensional accuracy, surface quality, and optical performance.

Coating and Finishing Operations

Anti-reflective coatings are applied in vacuum chambers using glow discharge and electrostatic cleaning. Magnesium fluoride is thermally evaporated at 300 °C to improve light transmission and protect the lens surface.

Assembly and Quality Control

The assembly stage combines multiple glass elements to form a complete lens system. This process requires precise manual work to ensure accurate alignment. It begins with thorough pre-assembly cleaning, followed by mounting lenses into barrels or sub-barrels using threaded retaining rings or adhesive cement.

Some lens designs require cementing elements together in a dust-free environment. In these cases, balsam cement is used to bond concave and convex surfaces, ensuring proper alignment and eliminating air bubbles or excess adhesive. Once internal components are secured, external structural parts and electronic elements, such as focusing rings and image stabilization systems, are added.

Final inspection includes axial and oblique ray testing to verify alignment and optical clarity. A range of tools is used for quality control, including lensometers (for measuring optical power and axis), spherometers (for surface curvature), interferometers (for optical quality), and autocollimators (for angular alignment).

Despite these rigorous checks, minor performance variations can still occur, particularly in lower-cost zoom lenses, due to looser manufacturing tolerances and reduced precision during assembly.^5,7,8

Recent Developments in Lens Manufacturing

Camera lens production continues to evolve through new technologies and design approaches.

AI-Driven Optimization of Optical Lens Design

Researchers at King Abdullah University of Science and Technology have developed DeepLens, an AI-driven model that automates optical lens design. This system uses curriculum learning to progressively address design complexities such as resolution, aperture, and field of view, creating optimized lens systems without human intervention.

Unlike conventional methods that make small, incremental adjustments, DeepLens generates optimized lens systems from scratch. This approach significantly shortens development timelines and reduces costs.

The method has successfully produced advanced optical systems, such as extended depth-of-field lenses with large viewing angles and aspheric surfaces. These designs show strong potential in applications where physical space is limited and computational optimization is key to maintaining image quality.⁹

Metasurface Folded Lens Technology for Ultrathin Modules

Traditional camera modules are often bulky due to the space required between vertically stacked refractive lenses.

To address this challenge, researchers at Stanford University and the Korea Institute of Science and Technology have developed a metasurface folded lens system. This system manipulates light with exceptional control over intensity, phase, and polarization while maintaining a lens module thickness of 0.7 mm.

This approach is especially promising for smartphones and AR/VR devices, where reducing lens thickness can eliminate the "camera bump" and enable more compact, sleek device designs.

The technology is also compatible with semiconductor fabrication methods, making it scalable for mass production. With further enhancement through AI-based image processing, it could form the basis for the next generation of ultrathin camera systems.¹⁰

A Sustainable and Flexible Alternative to Germanium

Germanium is widely used in camera lenses, particularly for infrared, thermal, and low-light imaging applications, due to its high refractive index and excellent infrared light transmission. However, rising costs and supply issues, driven by export restrictions, have led to a search for alternatives.

Chalcogenide materials have emerged as a potential replacement, offering wider spectral ranges and enhanced thermal and multispectral imaging flexibility. These materials also provide benefits such as reduced thickness and better performance in environments like fog and dust.

Although still in the experimental stage, chalcogenides show promise for reducing dependency on a single material source, offering improved supply chain stability and design flexibility.¹¹

The manufacturing of camera lenses is a complex process that integrates advanced optical science with precise engineering. As production methods and materials evolve, innovations will further enhance camera lenses' precision, efficiency, and versatility, reinforcing their essential role in modern imaging technologies.

To learn more about the technologies driving progress in imaging and optics, explore these related articles:

• New Camera Technology Revolutionizes Biological Imaging of Live Cells
• Revolutionizing Alpha-Particle Imaging: Breakthroughs and Future Horizons
• Hyperspectral Cameras: Advancing Precision Imaging
• Holographic Optical Elements for Imaging and Optical Processing

References and Further Reading

1. Maria Politarhos and Randy Matusow. (2023). Photography: What, How, Why – The Lens. https://pressbooks.cuny.edu/photographywhathowwhy/chapter/the-lens/
2. Kingslake, R. (2010). Lens design fundamentals. academic press. https://doi.org/10.1016/C2009-0-22069-1
3. Török, P. (2017). A course in lens design, by Chris Velzel: Scope: reference. Level: specialist, postgraduate. Contemporary Physics, 58(2), 179–180. https://doi.org/10.1080/00107514.2015.1124924
4. Sun, H. (2016). Lens design: a practical guide. Crc Press. https://www.routledge.com/Lens-Design-A-Practical-Guide/Sun/p/book/9781498750516?srsltid=AfmBOooIFBEWrLtXIDPYqPpv8RIZzOI5dDxlgOZ6x-GsQTngI3UWvmfP
5. Kubaczyk, D. M. (2011). Photographic lens manufacturing and production technologies (Doctoral dissertation, Massachusetts Institute of Technology). http://hdl.handle.net/1721.1/69779
6. Brandon. (2025). Introduction to Lens Design. https://www.photozone.de/lensDesignIntro
7. Dale. (2023). Go inside Sigma's factory to see how lenses are made. https://www.dpreview.com/articles/5410838737/go-inside-sigma-s-factory-to-see-how-lenses-are-made
8. Photonics. (2025). Lens Testing Equipment. https://www.photonics.com/EDU/lens_testing_equipment/d5105
9. Yang, X., Fu, Q., & Heidrich, W. (2024). Curriculum learning for ab initio deep learned refractive optics. Nature Communications, 15(1), 1-8. https://doi.org/10.1038/s41467-024-50835-7
10. Kim, Y., Choi, T., Lee, G. Y., Kim, C., Bang, J., Jang, J., ... & Lee, B. (2024). Metasurface folded lens system for ultrathin cameras. Science Advances, 10(44), eadr2319. https://doi.org/10.1126/sciadv.adr2319
11. Peter. (2024). Optics industry addresses the germanium issue. https://www.laserfocusworld.com/optics/article/55127439/lightpath-technologies-inc-optics-industry-addresses-the-germanium-issue

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