High-Speed, Compact, Adaptive Lenses Using In-Line Transparent Dielectric Elastomer Actuator Membranes

Electrically tunable adaptive lenses provide several advantages over traditional lens assemblies in terms of compactness, speed, efficiency, and flexibility. We present an elastomer-liquid lens system which makes use of an in-line, transparent electroactive polymer actuator. The lens has two liquid-filled cavities enclosed within two frames, with two passive outer elastomer membranes and an internal transparent electroactive membrane. Advantages of the lens design over existing systems include large apertures, flexibility in choosing the starting lens curvature, and electrode encapsulation with a dielectric liquid. A lens power change up to 40 diopters, corresponding to focal length variation up to 300%, was recorded during actuation, with a response time on the order of tens of milliseconds.Engineering and Applied Science

Optical MEMS

Optical microelectromechanical systems (MEMS), microoptoelectromechanical systems (MOEMS), or optical microsystems are devices or systems that interact with light through actuation or sensing at a micro- or millimeter scale. Optical MEMS have had enormous commercial success in projectors, displays, and fiberoptic communications. The best-known example is Texas Instruments’ digital micromirror devices (DMDs). The development of optical MEMS was impeded seriously by the Telecom Bubble in 2000. Fortunately, DMDs grew their market size even in that economy downturn. Meanwhile, in the last one and half decade, the optical MEMS market has been slowly but steadily recovering. During this time, the major technological change was the shift of thin-film polysilicon microstructures to single-crystal–silicon microsructures. Especially in the last few years, cloud data centers are demanding large-port optical cross connects (OXCs) and autonomous driving looks for miniature LiDAR, and virtual reality/augmented reality (VR/AR) demands tiny optical scanners. This is a new wave of opportunities for optical MEMS. Furthermore, several research institutes around the world have been developing MOEMS devices for extreme applications (very fine tailoring of light beam in terms of phase, intensity, or wavelength) and/or extreme environments (vacuum, cryogenic temperatures) for many years. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on (1) novel design, fabrication, control, and modeling of optical MEMS devices based on all kinds of actuation/sensing mechanisms; and (2) new developments of applying optical MEMS devices of any kind in consumer electronics, optical communications, industry, biology, medicine, agriculture, physics, astronomy, space, or defense

Actuation Of Droplets Using Transparent Graphene Electrodes For Tunable Lenses And Biomedical Applications

Variable focal length liquid microlenses are the next candidate for a wide variety of applications. Driving mechanism of the liquid lenses can be categorized into mechanical and electrical actuation. Among different actuation mechanisms, EWOD is the most common tool for actuation of the liquid lenses. In this dissertation, we have demonstrated versatile and low-cost miniature liquid lenses with graphene as electrodes. Tunable focal length is achieved by changing both curvature of the droplet using electrowetting on dielectric (EWOD) and applied pressure. Ionic liquid and KCl solution are utilized as lens liquid on the top of a flexible Teflon-coated PDMS/parylene membrane. Transparent and flexible, graphene allows transmission of visible light as well as large deformation of the polymer membrane to achieve requirements for different lens designs and to increase the field of view without damaging of electrodes. Another advantage of graphene compared to non-transparent electrodes is the larger lens aperture. The tunable range for the focal length is between 3 and 7 mm for a droplet with a volume of 3 μL. The visualization of bone marrow dendritic cells is demonstrated by the liquid lens system with a high resolution (more than 456 lp/mm). The Spherical aberration analysis is performed using COMSOL software to investigate the optical properties of the lens under applied voltages and pressure. We propose a prototype of compound eye with specific design of the electrodes using both tunable lenses and tunable supporting membrane. The design has many advantages including large field of view, compact size and fast response time. This work maybe applicable in the development of the next generation of cameras, endoscopes, cell phones on flexible platform. We also proposed here the design and concept of self-powered wireless sensor based on the graphene radio-frequency (RF) components, which are transparent, flexible, and monolithically integrated on biocompatible soft substrate. We show that a quad-ring circuit based on graphene transistors may simultaneously offer sensing and frequency modulation functions. This battery-free and transparent sensors based on newly discovered 2D nanomaterials may benefit versatile wireless sensing and internet-of-things applications, such as smart contact lenses/glasses and microscope slides

Miniaturization of optical spectrometers

Spectroscopic analysis is one of the most widely used analytical tools across both scientific research and industry. Whilst laboratory bench-top spectrometer systems offer superlative resolution and spectral range, their miniaturization is crucial for applications where portability is paramount, or in-situ measurements must be made. Advancement in this field over the last three decades is now yielding microspectrometers with performance and footprint near those viable for lab-on-a-chip systems, smartphones and other consumer technologies. In this review, we briefly summarize the technologies that have emerged toward achieving these aims - including miniaturized dispersive optics, narrowband filter systems, Fourier transform interferometers and reconstructive microspectrometers - and discuss the challenges associated with improving spectral resolution while device dimensions shrink ever further.EPSRC: EP/L016087/1 National Natural Science Foundation of China (51706141, 51976122

Electro-optic architecture for servicing sensors and actuators in advanced aircraft propulsion systems

A detailed design of a fiber optic propulsion control system, integrating favored sensors and electro-optics architecture is presented. Layouts, schematics, and sensor lists describe an advanced fighter engine system model. Components and attributes of candidate fiber optic sensors are identified, and evaluation criteria are used in a trade study resulting in favored sensors for each measurand. System architectural ground rules were applied to accomplish an electro-optics architecture for the favored sensors. A key result was a considerable reduction in signal conductors. Drawings, schematics, specifications, and printed circuit board layouts describe the detailed system design, including application of a planar optical waveguide interface

Perspective and Potential of Smart Optical Materials

The increasing requirements of hyperspectral imaging optics, electro/photo-chromic materials, negative refractive index metamaterial optics, and miniaturized optical components from microscale to quantum-scale optics have all contributed to new features and advancements in optics technology. Development of multifunctional capable optics has pushed the boundaries of optics into new fields that require new disciplines and materials to maximize the potential benefits. The purpose of this study is to understand and show the fundamental materials and fabrication technology for field-controlled spectrally active optics (referred to as smart optics) that are essential for future industrial, scientific, military, and space applications, such as membrane optics, light detection and ranging (LIDAR) filters, windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, and flat-panel displays. The proposed smart optics are based on the Stark and Zeeman effects in materials tailored with quantum dot arrays and thin films made from readily polarizable materials via ferroelectricity or ferromagnetism. Bound excitonic states of organic crystals are also capable of optical adaptability, tunability, and reconfigurability. To show the benefits of smart optics, this paper reviews spectral characteristics of smart optical materials and device technology. Experiments testing the quantum-confined Stark effect, arising from rare earth element doping effects in semiconductors, and applied electric field effects on spectral and refractive index are discussed. Other bulk and dopant materials were also discovered to have the same aspect of shifts in spectrum and refractive index. Other efforts focus on materials for creating field-controlled spectrally smart active optics (FCSAO) on a selected spectral range. Surface plasmon polariton transmission of light through apertures is also discussed, along with potential applications. New breakthroughs in micro scale multiple zone plate optics as a micro convex lens are reviewed, along with the newly discovered pseudo-focal point not predicted with conventional optics modeling. Micron-sized solid state beam scanner chips for laser waveguides are reviewed as well

Optical Fluid-based Photonic And Display Devices

Conventional solid-state photonic devices exhibit an ultra-high optical performance and durability, but minimal adaptability. Recently, optical fluid-based photonic and display devices are emerging. By dynamically manipulating the optical interface formed by liquids, the optical output can be reconfigured or adaptively tuned in real time. Such devices exhibit some unique characteristics that are not achievable in conventional solid-state photonic devices. Therefore, they open a gateway for new applications, such as image and signal processing, optical communication, sensing, and lab-on-a-chip, etc. Different operation principles of optical fluidbased photonic devices have been proposed, for instance fluidic pressure, electrochemistry, thermal effect, environmentally adaptive hydrogel, electro-wetting and dielectrophoresis. In this dissertation, several novel optical fluid-based photonic and display devices are demonstrated. Their working principles are described and electro-optic properties investigated. The first part involves photonic devices based on fluidic pressure. Here, we present a membrane-encapsulated liquid lens actuated by a photo-activated polymer. This approach paves a way to achieve non-mechanical driving and easy integration with other photonic devices. Next, we develop a mechanical-wetting lens for visible and short-wavelength infrared applications. Such a device concept can be extended to longer wavelength if proper liquids are employed. In the second part, we reveal some new photonic and display devices based on dielectrophoretic effects. We conceive a dielectric liquid microlens with well-shaped electrode for fixing the droplet position and lowering the operating voltage. To widen the dynamic range, we demonstrate an approach to enable focus tuning from negative to positive or vice versa in a single dielectric lens without any moving part. The possibility of fabricating microlens arrays iv with different aperture and density using a simple method is also proposed. Furthermore, the fundamental electro-optic characteristics of dielectric liquid droplets are studied from the aspects of operating voltage, frequency and droplet size. In addition to dielectric liquid lenses, we also demonstrate some new optical switches based on dielectrophoretic effect, e.g., optical switch based on voltage-stretchable liquid crystal droplet, variable aperture or position-shifting droplet. These devices work well in the visible and near infrared spectral ranges. We also extend this approach to display and show a polarizer-free and color filter-free display. Simple fabrication, low power consumption, polarization independence, relatively low operating voltage as well as reasonably fast switching time are their key features

MEMS-tunable dielectric metasurface lens

Varifocal lenses, conventionally implemented by changing the axial distance between multiple optical elements, have a wide range of applications in imaging and optical beam scanning. The use of conventional bulky refractive elements makes these varifocal lenses large, slow, and limits their tunability. Metasurfaces, a new category of lithographically defined diffractive devices, enable thin and lightweight optical elements with precisely engineered phase profiles. Here we demonstrate tunable metasurface doublets, based on microelectromechanical systems (MEMS), with more than 60 diopters (about 4%) change in the optical power upon a 1-μm movement of one metasurface, and a scanning frequency that can potentially reach a few kHz. They can also be integrated with a third metasurface to make compact microscopes (~1 mm thick) with a large corrected field of view (~500 μm or 40 degrees) and fast axial scanning for 3D imaging. This paves the way towards MEMS-integrated metasurfaces as a platform for tunable and reconfigurable optics

A fluorescent oil detection device

On April 20th 2010, the largest offshore oil spill in U.S. history happened in the Gulf of Mexico. It is estimated total more than 4 million barrels oil spilled to Gulf of Mexico. More than two million gallons had been used. This had made the threat to coastal and sea ecosystem even greater and long term. Real-time monitoring is also a critical topic for oil spill response. In-situ monitoring devices are needed for rapid collection of real-time data. A new generation of instruments for spilled oil detection is reported in this paper. The main hypothesis in this research is that the sensitivity of the new instrument based on a micro-fluidic-optic chip can be higher than its conventional sized counterparts. The adoption of the micro-fluidic-optic chip helped to miniaturize the sample extraction unit and also to integrate the optical detection on the same chip substrate. Only the monitoring and displaying unit and the power supply were external to the micro-fluidic-optic chip. In this way, the micro-fluidic-optic chip is replaceable and can be disposable. This also helps to eliminate the need for cleaning the fluidic components, which may be very difficult in micro-scales because of surface tension and flow resistances. Liquid-Liquid extraction unit for sample pre-concentration and micro-optic components for fluorescence detection are the key microfluidic components and have been designed and fabricated on a single disposable chip. In the Liquid-Liquid extraction system, different designs are compared and electromagnetically actuated micro-valves and peristaltic pumps have been designed and fabricated to control the aqueous sample fluid and the organic phase solution. In the micro-optic detection system, different designs are compared and an out-of-plane lens was designed, fabricated, and integrated to enhance the measurement sensitivity. The experimental results of the integrated system have proved that the liquid-liquid extraction functioned very well and the overall measurement sensitivity of the system has been increased more than six hundred percent. An overall oil detection sensitivity blow 1ppm has been achieved. The research work presented in this dissertation has proved the feasibility of this novel oil detection instrument based on micro-fluidic-optic chip. This detection system may also be used for detection of other samples that can be measured based on fluoresce principles

Optical packaging of microlens over UV-LED array

Abstract unavailable please refer to PD