Refractive lenses are an 800-year-old technology that has stood the test of time. Glasses, cameras, and microscopy are all applications that rely on lenses to redirect light by varying the optical path through a curved piece of glass or plastic. However, the underlying architecture of lenses may be about to change.
Metalenses: A Compact Alternative
Metamaterials offer the potential to revolutionize such lensing systems. Where conventional lenses rely on refraction at interfaces to focus light, metamaterial lenses (or "metalenses") instead utilize a finely patterned surface to vary the effective refractive index across the lens, introducing phase variation and changing the direction of the light via interference.
So why are these metamaterials of interest? Firstly, unlike glass lenses, the finely patterned metalenses can be made from silicon wafers using conventional lithography processes. Utilizing an established, highly scalable manufacturing method greatly reduces adoption barriers and could also enable simpler supply chains since both the lens and image sensor can be produced simultaneously.
Form factor is another significant advantage. While the focusing power of a conventional lens depends on its curvature, the alternative operating principle of metalenses means that they can be flat. This reduces both weight and the required size of the lens housing, allowing for the elimination of the "camera bulge" common to modern smartphones. The potential benefits for smartphone designers and manufacturers are twofold: a reduction in cost due to integrated manufacturing and additional product differentiation in an increasingly homogenous smartphone market. Since a metalens can replace any small camera lens, this twin value proposition also applies to applications requiring compact cameras such as laptops and tablets.
Metalenses potentially enable the creation of flat lenses - this would allow for significant reductions in form factor for lens casing, enabling slimmer form factors and product differentiation for consumer electronics such as mobile phones. Source: IDTechEx
Use cases for metalenses extend beyond consumer electronics. Compatibility with time-of-flight depth sensors, metalenses can be integrated with LiDAR systems for autonomous vehicles and robots. Metalenses can also be used with dot projection systems for facial recognition. Additionally, the ability to have fine spatial control of phase can allow imaging at length scales below the diffraction limit (i.e., 100s of nm), enabling affordable high-resolution microscopy of features.
Status and Challenges
Some technical challenges need to be resolved for metalenses to meet the requirements of these compelling applications. Arguably the biggest difficulty is overcoming chromatic aberration. At present, different wavelengths of light are focused onto different points, which leads to a blurry full-color image. Efforts are being made to overcome this challenge, such as developing more complex sub-wavelength structures designed with sophisticated modeling software or by introducing algorithmic processing.
Clearly, this technical challenge doesn't apply to single-wavelength systems. Time-of-flight sensors for consumer devices are a prominent example, where metalenses are now entering commercialization. As metalenses see further technological and commercial development, they are set to gain substantial traction for both compact cameras and microscopy through their promise of reduced production costs, compact form factors, and imaging below the diffraction limit.
In the IDTechEx report, "Metamaterials Markets 2023-2043: Optical and Radio-Frequency", the potential of metalenses is analyzed in depth to assess the potential for this emerging technology in consumer electronics. Drawing on company interviews and extensive research, this report evaluates technical aspects of both optical and radio-frequency metamaterials, including manufacturing processes, materials selection, value propositions, and comparisons of metamaterial-based systems against competing technologies. This report includes 20-year market forecasts covering 14 applications of electromagnetic metamaterials across 42 distinct forecast lines, expressed as revenue, surface area, and volume of products sold.
To find out more about this IDTechEx report, including downloadable sample pages, please visit www.IDTechEx.com/Meta.
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