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Optical Design & Engineering


Patent news: A renewed focus on Newton's technology

This month's featured patent review by analysts from Nerac
12 March 2007, SPIE Newsroom. DOI: 10.1117/2.2200703.0002
Sir Isaac Newton is recorded to have made a focusing mirror by spinning a liquid, most likely mercury, to focus. Large telescopes still use that technology today. Recently, there has been a renewed interest in this ancient technology that has led to a resurgence of patent activity in the past year.
Current products that use the lenses include camera phones and compact digital cameras. The main attraction is the ability to get high resolution in a small package, usually less than 3mm. A French company, Varioptic, is a leader in this area with variable focal length lenses. New patents are coming out that offer auto-focus. Varioptic has said that it is working on a zoom liquid lens but no patents have been made public yet. Samsung indicated that an extension of its patent would be zoom lenses.
In general, fluid lenses can be broken down into four types:
  • Fixed volume, where the periphery is moved to adjust the curvature of the lens.
  • Variable volume, where fluid is pumped in or out to change the curvature.
  • Electrowetting mechanism, where an electrical charge is applied to fluid surface to affect a contact angle change. This appears to be the more common method in use today.
  • Pressure induced system that is similar to the fixed volume system but instead of the periphery moving, one of the surfaces moves.
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    Patent 02874707/FR-A1 VARIABLE LENS A FOCAL annotated title: LENTILLE A FOCALE VARIABLE by Varioptic
    This is a patent that describes how this new generation of liquid lenses work. It is the electrowetting (electromouillage) type. It is a practical and detailed description of both the materials and the performance of such a lens design.
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    Patent Application - 20060155372/US-A1 OCULAR AUTO-FOCUSING LENSES
    It was only a matter of time before someone applied this technology to the human eye. This patent application suggests a fluid lens for a liquid-focused accommodating lens to restore or enhance of a patient's vision. It is proposed as an alternate to the intraocular lens implants or the expensive multi-focal contact lens. "The present invention is based on the finding that patients with vision disorders, and in particular, disorders involving the crystalline lens of the eye, can benefit from highly modified lenses originally developed specifically for use in image-capturing devices such as cameras."
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    This is a more current standard liquid lens design. Typical applications suggested are digital and video cameras, microscopes or endoscopes. The object of this invention is to provide a system to allow the optical power to be modified and at the same time correct at least one optical aberration. The variable focus liquid lenses are the electrowetting type and are used in pairs to correct a particular optical aberration.
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    The object of this invention is to provide an auto-focusing system for a camera that is capable of being manufactured in a small size with high resolution. One reference use is a cellular phone with built-in camera. The design is a combination liquid-lens and standard-lens configuration, where the liquid lens creates the auto-focus feature. One extension of this patent is it can be readily applied to an optical system including a camera module having an optical zoom function.
    Jerry Burke is a Nerac analyst with 45 years of experience in engineering and research and development whose primary focus is medical devices and optics. He has been involved with developing fiber optic devices used in imaging and illumination for such organizations as NASA, the military, universities, and research groups such as Lawrence Livermore Labs. Nerac analysts work with clients in the following critical areas:
    • Patentability and Invalidity
    • Patent Portfolio Analysis
    • Commercialization Strategy
    • White Space Analysis