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Even Illumination From Fiber-Optic-Coupled Laser Diodes

Emerging light beams would be shaped by diffractive fiber-optic tips. Marshall Space Flight Center, Alabama A method of equipping fiber-optic-coupled laser diodes to evenly illuminate specified fields of view has been proposed. The essence of the method is to shape the tips of the optical fibers into suitably designed diffractive optical elements. One of the main benefits afforded by the method would be more nearly complete utilization of the available light.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs, TSP

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Excimer Leverages Litho Lessons for kHz Micromachining

Features developed for lithography light sources are creating a mid-tier excimer laser niche. Coherent, Santa Clara, California Ultraviolet lasers currently are used in a very diverse range of industries and applications. This is because their high-energy photons directly can break inter-atomic bonds in many materials, and the short wavelength enables a high degree of spatial resolution (see Figure 1). Amongst ultraviolet lasers, excimers are unique in their ability to deliver a combination of high pulse energy and high average power. Because of these advantages, excimers are used in applications as diverse as ophthalmic corrective procedures, low-temperature silicon annealing for flat-panel displays, drilling inkjet nozzles, and treating the cylinder liners of diesel engines for greener automobile performance.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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QC Lasers Improve Hazardous Gas Monitoring

The measurement of gases associated with industrial processing/emissions monitoring has become increasingly important as the need to improve efficiencies in process control has increased, and legislation governing emissions has come into force. Gases including NOx, SOx, CO2, CO, NH3, and H2O commonly are used to assess processes such as combustion and quenching, while many fall under emissions legislation resulting from the Kyoto agreement.

Posted in: Features, ptb catchall, Photonics, Motion Control, Articles

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LUTs: Take Control of Your Imaging Application

It is hard to see how machine-vision camera manufacturers produce decent-quality products at reasonable prices. The multi-megapixel sensors at the heart of current machine-vision cameras are among the largest of VLSI (very-large-scale integration) semiconductor chips, and it is almost impossible to make them with the pixel-to-pixel uniformity required for high-precision imaging applications. Without some way of compensating for manufacturing variations across a given image sensor, many otherwise acceptable chips would have to be discarded. That would drastically reduce manufacturing yields and drive sensor-chip prices far beyond levels acceptable for many applications.

Posted in: Features, ptb catchall, Photonics, Articles

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Water Jets and Lasers Cut Through Electronic Industry’s Problems

Semiconductor manufacturers need the flexibility of a wafer-cutting machine that supports various wafer sizes and cuts them without the mechanical and thermal damage often seen with traditional cutting methods, including the mechanical stress that occurs with conventional sawing, or the contamination and/or ablated material caused by laser cutting. Employing a dicing process that makes the wafers less prone to breakage would allow manufacturers to introduce thinner wafers into the production line, thereby increasing the number of functions on a given device. A machine that cuts lasers without a heat-affected zone would also offer efficiency advantages to manufacturers.

Posted in: ptb catchall, Applications, Photonics, Application Briefs

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Full-Duplex Digital Communication on a Single Laser Beam

The laser beam would be transmitted with one modulation and retroreflected with another modulation. Goddard Space Flight Center, Greenbelt, Maryland A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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Stabilizing Microwave Frequency of a Photonic Oscillator

Microwave frequency is stabilized by stabilizing optical frequency to an atomic transition. NASA’s Jet Propulsion Laboratory, Pasadena, California A scheme for stabilizing the frequency of a microwave signal is proposed that exploits the operational characteristics of a coupled optoelectronic oscillator (COEO) and related optoelectronic equipment. An essential element in the scheme is a fiber mode-locked laser (MLL), the optical frequency of which is locked to an atomic transition. In this scheme, the optical frequency stability of the mode-locked laser is transferred to that of the microwave in the same device. Relative to prior schemes for using wideband optical frequency comb to stabilize microwave signals, this scheme is simpler and lends itself more readily to implementation in relatively compact, rugged equipment. The anticipated development of small, low-power, lightweight, highly stable microwave oscillators based on this scheme would afford great benefits in communication, navigation, metrology, and fundamental sciences.

Posted in: Tech Briefs, ptb catchall, Photonics, Briefs

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