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This paper reports the fabrication and the characterization of a black silicon based iris that shows significant reduction in the unwanted stray light due to scattering and reflection on the iris surfaces. The iris was characterized by recording the far-field diffraction pattern at a 532-nm wavelength. The intensity at dark rings is reduced by a factor of up to 5, which makes the bright 0th order...
This paper demonstrates sub-10-nanometer (nm) laser ablation on hard materials. An 800-nm-wavelength femtosecond laser is focused down to sub-diffraction-limited scale by a silicon nanophotonic structure fabricated on a silicon-on-isolator (SOI) substrate, which is utilized to enable the ablation on the silicon dioxide (SiO2) layer of the SOI. Atomic force microscopy (AFM) results show a minimum ablation...
We describe the fabrication of a flexible electrowetting microlens array. The microlenses are composed of two immiscible liquids on a flexible substrate. The areal density modulated electrode design utilized for electrowetting allows for the independent, continuous tuning of the individual microlenses and additionally functions to keep each lens centered on its optical axis. Simultaneously, the flexible...
This paper reports on a novel double-sided design of an electrode structure that drives a tunable liquid microlens based on the dielectrophoretic force. The clear advantage of our double-sided design over previously reported conventional single-sided design of electrodes for tunable electro-hydrodynamic lenses is the much lower driving voltage, given similar device scale on the order of 1mm of lens...
In this article, we present a camouflage sheet consisting of nanophotonic structures that can manage thermal signature of objects. Photonic structures that can absorb a wide range of mid-infrared wavelengths were transferred onto flexible substrates to cover objects and absorb their infrared radiations. Transmission and reflection of surface can be reduced by silicon nanowires in the desired region...
A novel patch-based multi-view image denoising algorithm is proposed. This method leverages the 3D focus image stacks structure to exploit self-similarity and image redundancy inherent in multiple view images. Then a depth-guided adaptive window and dynamic view selection criterion is developed to aid proper selection of most consistent patches for the multi-view image denoising. Extensive experiments...
This paper presents a flexible, three-axis, rapidly prototyped capacitive touch sensor that utilizes a patterned elastomeric dielectric layer. The sensor was fabricated from a copper clad kapton laminate and is capable of resolving normal pressure and tracking directional motion. In a mock clinical breast examination (CBE) setup, we used a breast model to demonstrate that the sensor, when placed under...
For super resolution (SR) of a 3D scene from multi-view low resolution (LR) images, subpixel registration is one of the main problems due to the difference of the depth for different objects, especially for hand-held uncalibrated cameras. In this paper we proposed a method to solve this problem by estimating the depth map for the LR images and treating the registration as a planar segmentation problem...
In this paper, we propose an improved fast multiple-view image denoising algorithm based on plane sweeping (PS) and non-local means (NLM). Miyata et al. proposed to use PS to convert multi-view images into multi-focus images for noise suppression. It showed improved computational efficiency and comparable denoising quality compared to conventional methods. In this paper, we introduce the notion of...
Liquid lens technology is a rapidly progressing field driven by the promise of low cost fabrication, faster response, fewer mechanical elements, versatility and ease of customization for different applications. Here we present the use of liquid lenses for biomedical optics and medical imaging. I will specifically focus on our approaches towards the development of three ex-vivo and in-vivo liquid-lens...
We present a new technique to design a dual-band patch antenna whose response can be changed dynamically using a fluidic tuning mechanism. Using this technique, a dual-band patch antenna operating at 2.5 GHz is designed. Two oil-filled channels are placed in the substrate of the antenna along the non- radiating edges of the patch antenna and filled with liquid (or solid) metal cylinders. As the cylinders...
This paper describes microlens arrays implemented on a flexible substrate. For the first time, we have demonstrated binary Fresnel zone plates fabricated from silicon nanowires embedded in a PDMS matrix. Lens arrays on flexible substrates can potentially benefit from an increased field of view, which is important for applications such as microscopy and surveillance. Lens arrays have wide applications...
Silicon nanowire reflective Fresnel lenses are demonstrated and their focusing and lensing properties characterizations are shown. The Fresnel lenses were fabricated using conventional lithography and metal-assisted chemical etching. The lenses have dark zones made of sub-wavelength silicon nanowires and bright zones formed by polished silicon surface. High intensity contrast exists between the bright...
Clostridium Botulinum neurotoxins (BoNTs) are the most lethal bacterial toxins known to humankind in nature. They present grave bioterrorism concern, especially within food supplies. The current pharmacotoxicological mouse bioassay accepted for detection of BoNT in food is laborious and expensive, lacks specificity, or may cause false alarm. It is highly desired to develop a rapid and sensitive on-site...
A new sensor design for detecting water hardness using complexometric and colorimetric concepts has been presented in this paper. Calmagite, a metal ion indicator, changes color of a solution to wine red in presence of calcium (Ca2002B;) and magnesium (Mg2002B;) ions at pH 10. When Ethylenediaminetetraacetic acid (EDTA) is added to the solution, it displaces the indicator from the metal-indicator...
We propose a novel method for capturing high-speed, high dynamic range video with a single low-speed camera using a coded sampling technique. Traditional video cameras use a constant full-frame exposure time, which makes temporal super-resolution difficult due to the ill-posed nature of inverting the sampling operation. Our method samples at the same rate as the traditional low-speed camera but uses...
We report on a flexible liquid microlens actuated by electrowetting mechanism. The microlens structure is made of soft polymer and its substrate is made much thinner than the lens to reduce the stress on the lens when it is stretched on a curved surface. A low-temperature fabrication process is developed to reduce the stress in the polymer. The focal length f can be varied between −14 mm and 33 mm...
We present a prototype of a micro panoramic vision system that includes five micro-cameras controlled simultaneously by mechanical arm-like actuators, structurally similar to umbrella ribs. Each camera rests on an arm that can be oriented at an angle simultaneously with the other four arms. This arrangement offers reconfigurable angle of view and depth perception. Stitching of the images from individual...
Most optical systems utilize refractive lenses to focus light. These lenses have low transmission and suffer chromatic aberration because the refractive index is a function of wavelength. Focusing light by reflective curved surfaces (e.g., spherical mirrors) could address these two issues. However, this is hard to implement in micro-optical systems since the imager, with similar dimensions to other...
We report on polydimethlysiloxane (PDMS) microlenses fabricated from liquid-phase photopolymerization and a single molding step. The mold is fabricated by photopolymerizing a polyacrylamide (PAAm) pre-hydrogel flowed into an aperture array with a channel underneath. PAAm shrinks isotropically while pinned around the rim of the apertures to form lens molds due to hydrophobic-hydrophilic boundaries...
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