Photonics/Optics

An Electron Caught in the Act

How fast is an electron? Australian scientists were able to measure it. Australia's fastest camera, located at the Attosecond Science Facility, has revealed the time it takes for molecules to break apart. The experimental research, conducted by Griffith University's Centre for Quantum Dynamics, aims to help in the design of new molecules for materials science or drug discovery.

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Scientists Demonstrate New Real-Time Technique for Studying Ionic Liquids at Electrode Interfaces

Ionic liquids—salts made by combining positively charged molecules (cations) and negatively charged molecules (anions) that are liquid at relatively low temperatures, often below room temperature—are increasingly being investigated for uses in batteries, supercapacitors, and transistors. Their unique physical and chemical properties, including good ionic conductivity, low flammability and volatility, and high thermal stability, make them well suited for such applications. But thousands of ionic liquids exist and exactly how they interact with the electrified surfaces of electrodes remains poorly understood, making it difficult to choose one for a particular application.

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Optical Probing Deep into the Eye

Optical coherence tomography (OCT) is a scanning technology commonly used by ophthalmologists to check for eye diseases. A team of scientists has figured out how to retrofit these high-performance machines with off-the-shelf components, increasing OCT's resolution by several-fold, promising earlier detection of retinal and corneal damage, incipient tumors, and more.

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Novel Techniques Examine Solar Cells with Nanoscale Precision

Researchers at the National Institute of Standards and Technology (NIST) have for the first time examined, with nanometer-scale precision, the variations in chemical composition and defects of widely used solar cells. The new techniques, which were used to investigate a common type of solar cell made of the semiconductor material cadmium telluride, promise to aid scientists to better understand the microscopic structure of solar cells and may ultimately suggest ways to boost the efficiency with which they convert sunlight to electricity.

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R&D Effort Produces Magnetic Devices to Enable More Powerful X-ray Lasers

A team of researchers have designed, built, and tested two devices, called superconducting undulators, which could make X-ray free-electron lasers (FELs) more powerful, versatile, compact, and durable.

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2.2-Micron, Uncooled, InGaAs Photodiodes and Balanced Photoreceivers up to 25-GHz Bandwidth

Traditional applications for 2-micron photodetectors have been largely dominated by passive remote sensing where detectors having bandwidth of even one megahertz are deemed sufficient. The onus in such applications is to achieve low dark current through active cooling. The advent of high-power, 2-micron-wavelength lasers has made coherent LiDARs viable for active sensing applications. Such a system needs photodetectors that can handle high local oscillator optical power and have large bandwidth. Through a combination of high coherent gain and small integration time, a large signal-to-noise ratio can be achieved. Operation at high optical power levels reduces the significance of photodiodes' dark current. As a result, uncooled operation at room temperature is feasible, simplifying the overall instrument design.

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Compact, Lightweight, Athermal, Nanocomposite Telescopes with Freeform Optics

Small space missions such as CubeSats frequently require telescopes with highly sophisticated optical systems that are also low in mass and cost. The very limited spacecraft volume and mass limits also preclude adjustments to maintain critical alignment with change in temperature. Existing systems, especially those that employ folded optical paths with freeform optics, are expensive to fabricate. The optics, and support and metering structures, are also heavy due to the use of high-density material such as glass, aluminum, or nickel.

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High-Resolution, Coherent, Dual-Tip Scanning Probe Microscope

The scanning tunneling microscope (STM) has become one of the most powerful tools used in studying the surface structure of electrically conducting solid-state materials at an atomic resolution. Since its conception, the STM has had the greatest impact in the field of modern surface science because of its superior capability of characterizing and resolving the surface atomic structures and defects. Surface features such as atomic point defects, dislocations, and grain boundary identification can routinely be studied using a STM. Furthermore, STMs also allow the characterization of step structures at the atomic level during the processes of surface preparation and growth of semiconductors, such as epitaxial growth on semiconductor structures.

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Fiber-Optic Environmental Radiation Dosimeter

An all-optical, fiber-optic-coupled remote radiation sensor was developed using luminescent, copper-doped quartz material. The key to the technology is the doped quartz material, which produces a luminescence signal that is directly proportional to the radiation dose.

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X-Ray Scattering Constructs 3D Images of Nanoparticle Grains

Scientists at Argonne National Laboratory have developed a new X-ray technique to see inside continuously packed nanoparticles, also known as grains, to examine deformations and dislocations that affect their properties.

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