. | . |
First flat lens for immersion microscope provides alternative to centuries-old technique by Staff Writers Boston MA (SPX) May 22, 2017
A team of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has developed the first flat lens for immersion microscopy. This lens, which can be designed for any liquid, may provide a cost-effective and easy-to-manufacture alternative to the expensive, centuries-old technique of hand polishing lenses for immersion objectives. "This new lens has the potential to overcome the drawbacks and challenges of lens-polishing techniques that have been used for centuries," said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS, and senior author of the paper. When light hits an object, it scatters. Optical microscopes work by collecting that scattered light through a series of lenses and reconstructing it into an image. However, the fine detailed geometrical information of an object is carried by the portion of scattered light propagating with angles too large to be collected. Immersing the object in a liquid reduces the angles and allows for the capturing of light that was previously impossible, improving the resolving power of the microscope. Based on this principle, immersion microscopes use a layer of liquid - usually water or oil - between the specimen slide and the objective lens. These liquids have higher refractive indices compared to free space so the spatial resolution is increased by a factor equal to the refractive index of the liquid used. Immersion microscopes, like all microscopes, are comprised of a series of cascading lenses. The first, known as the front lens, is the smallest and most important component. Only a few millimeters in size, these semicircular lenses look like perfectly preserved rain drops. Because of their distinctive shape, most front lenses of high-end microscopes produced today are hand polished. This process, not surprisingly, is expensive and time-consuming and produces lenses that only work within a few specific refractive indices of immersion liquids. So, if one specimen is under blood and another underwater, you would need to hand-craft two different lenses. To simplify and speed-up this process, SEAS researchers used nanotechnology to design a front planar lens that can be easily tailored and manufactured for different liquids with different refractive indices. The lens is made up of an array of titanium dioxide nanofins and fabricated using a single-step lithographic process. "These lenses are made using a single layer of lithography, a technique widely used in industry," said Wei Ting Chen, first author of the paper and postdoctoral fellow at SEAS. "They can be mass-produced with existing foundry technology or nanoimprinting for cost-effective high-end immersion optics." Using this process, the team designed metalenses that can not only be tailored for any immersion liquid but also for multiple layers of different refractive indices. This is especially important for imaging biological material, such as skin. "Our immersion meta-lens can take into account the refractive indices of epidermis and dermis to focus light on the tissue under human skin without any additional design or fabrication complexity," said Alexander Zhu, coauthor of the paper and graduate student at SEAS. "We foresee that immersion metalenses will find many uses not only in biological imaging but will enable entirely new applications and eventually outperform conventional lenses in existing markets," said Capasso. The research is described in Nano Letters.
Hanover, NH (SPX) May 17, 2017 In an effort to make digital smartwatches more convenient for their users, researchers at Dartmouth College and the University of Waterloo have produced a prototype watch face that moves in five different directions. With the ability to rotate, hinge, translate, rise and orbit, the model dramatically improves functionality and addresses limitations of today's fixed-face watches. The concep ... read more Related Links Harvard School of Engineering and Applied Sciences Satellite-based Internet technologies
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |