Special Coverage

NASA Supercomputer Simulations Reveal 'Noisy' Aerodynamics
Robotic Gripper Cleans Up Space Debris
Soft Robot “Walks” on Any Terrain
Defense Advanced Research Projects Agency
Using Microwaves to Produce High-Quality Graphene
Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat
Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space

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.

Posted in: Briefs, Photonics
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Line Scan Cameras

Area array and line scan cameras are each suited for unique machine vision applications. Area array cameras, for all intents and purposes, are “conventional” cameras that use sensors with two-dimensional pixel arrays. The square or rectangular shaped sensor captures an image in a single pass with the resulting image having a width and height corresponding to the number of pixels on the sensor, for example, 640x480. Because of this, area array cameras are ideal for machine vision tasks where objects are small or have approximately the same size in both dimensions. However, the size of PCBs, LCD panels, and wafers has increased beyond the speed, accuracy, and resolution capabilities of many area array cameras. Line scan cameras offer a better solution.

Posted in: Articles, Photonics
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Improved Surface Characterization with AFM Imaging

To shrink device size yet still tightly control performance, new technology often requires increasingly stringent surface specifications. Characterization tools, in turn, must keep pace by providing higher resolution, faster throughput, and more functionality. The atomic force microscope (AFM) is well known as a high-resolution imaging technique, but its characterization power and ease of use have increased significantly over the years.

Posted in: Application Briefs, Photonics
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Optical Monitoring System Enables Greater Accuracy In Thin-Film Coatings

The challenges in achieving greater accuracy in optical thin-film coatings, both historically and in today's coating processes, are many and deserve our scrutiny. The “old” way of designing and manufacturing coatings was to use a thin-film design software like TFCalc, which included analysis, optimization, results, optical data, and coating files. In this instance, one would create a design using high-, medium-, and low-index materials to come up with a theoretical design (Figure 1). The design of the coatings would be the easy part; the hard part comes in replicating the design thickness and the material indexes inside the coating chamber each and every time.

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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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The Eyes Of The Instruments: Using Optical Filters To Observe And Measure Earth From A Different Perspective

Earth Observation (EO) remote sensing provides the ability to measure, understand, and hopefully manage for purposes of commerce, safety and security, and science, our environment and our impact/interaction with it. In EO instruments, single wavelength band measurements are often necessary to allow observation of unique spectral characteristics representative of specific atmospheric and environmental phenomena. Optical filters with their ability to provide highly selective single band and multi-spectral wavelength discrimination in robust and reliable formats are a key contributor in photonics based EO instruments, serving as “the eyes of the instruments”.

Posted in: White Papers, Photonics
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When Stars Collide: LIGO Detects Gravitational Waves from ‘Kilonova’ Light Show

In the galaxy NGC 4993, located approximately 130 million light-years from Earth, two neutron stars collided. And, for the first time, scientists detected the gravitational waves to prove it. They may have even solved the long-standing mystery about the origin of gold and platinum.

Posted in: News, Aeronautics, Imaging, Materials, Optics
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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.

Posted in: Briefs, Photonics
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