Photonics/Optics

Flexible Laser Design Targets Low-Volume Material Processing Needs

A flexible approach to diode-pumped laser design combines customized performance with cost-effective manufacturing.

Coherent, Inc., Santa Clara, California

Q-switched, diode-pumped solid-state lasers with an end-pumped cavity design are now widely used in micromachining, materials processing, marking, and related applications. They are used to process a broad range of materials including metals, glass, plastics, and semiconductors. But this application diversity creates a concomitant need for laser diversity. Namely, while each application requires superior reliability and performance, the definition of “superior performance” is very application-specific. For example, some metal ablation applications may benefit from a long laser pulse, whereas semiconductor scribing needs a short pulse and a very high pulse repetition rate.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics, Lasers, Product development, Forming
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Aligning Optical Fibers by Means of Actuated MEMS Wedges

Wedges would be fabricated using gray-scale exposure of photoresist.

Microelectromechanical systems (MEMS) of a proposed type would be designed and fabricated to effect lateral and vertical alignment of optical fibers with respect to optical, electro-optical, optoelectronic, and/or photonic devices on integrated circuit chips and similar monolithic device structures. A MEMS device of this type would consist of a pair of oppositely sloped alignment wedges attached to linear actuators that would translate the wedges in the plane of a substrate, causing an optical fiber in contact with the sloping wedge surfaces to undergo various displacements parallel and perpendicular to the plane. In making it possible to accurately align optical fibers individually during the packaging stages of fabrication of the affected devices, this MEMS device would also make it possible to relax tolerances in other stages of fabrication, thereby potentially reducing costs and increasing yields.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics, Fiber optics, Integrated circuits, Microelectromechanical devices, Sensors and actuators, Fabrication
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Optical Characterization of Molecular Contaminant Films

A theoretical model is correlated with measured spectral transmittances and VUV exposures of spacecraft optics.

Lyndon B. Johnson Space Center, Houston, Texas

A semi-empirical method of optical characterization of thin contaminant films on surfaces of optical components has been conceived. The method was originally intended for application to films that become photochemically deposited on such optical components as science windows, lenses, prisms, thin-film radiators, and glass solar-cell covers aboard spacecraft and satellites in orbit. The method should also be applicable, with suitable modifications, to thin optical films (whether deposited deliberately or formed as contaminants) on optical components used on Earth in the computer microchip laser communications and thin-film industries.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics, Optics, Coatings, colorants, and finishes, Glass, Satellites, Spacecraft
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Digital Servos, Software Chart New Directions in Optical Scanning

Optical scanners, or servo-controlled, limited-rotation motors with laser-beam steering mirrors, were first introduced 40 years ago by General Scanning. Since then, they have become the enabling technology behind many innovative products across many different industries, including medical imaging, industrial machining, product identification, biomedical research, automotive manufacturing, and many more.

Posted in: Articles, Features, ptb catchall, Photonics, Lasers, Optics, Medical equipment and supplies, Manufacturing equipment and machinery, Electric motors, Industrial vehicles and equipment
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Design Software Bridges Optical/Mechanical Gap for Life Sciences

The inherently interdisciplinary nature of developing instrumentation for life sciences requires a high level of collaboration between scientists and engineers across the fields of analytical or clinical chemistry, optics, mechanics, material science, and microbiology. Moreover, product development teams are competing for first-tomarket benefits that are driven by intellectual property lifetimes and insuring an installed base quickly to realize recurring consumable sales. Concurrently, product designers need to comply with current Good Manufacturing Practices (cGMP). System-level modeling enables adherence to the methodical design process without the cost and time associated with iterative hardware prototyping and laboratory and clinical testing.

Posted in: Application Briefs, Applications, ptb catchall, Photonics, CAD, CAM, and CAE, Medical, health, and wellness, Collaboration and partnering, Product development, Quality standards
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Deformable Mirror to Help NASA Search for New Planets

Boston Micromachines, a provider of MEMS-based deformable mirror products for adaptive optics systems, is developing a deformable mirror that will aid NASA in the search for extra-solar planets. The mirror comprises a micromirror array consisting of 331 closely packed ultra-flat hexagonal mirror elements. Each element is capable of tip, tilt, and piston motion with nanometer precision as required for a space-based, hyper-contrast coronagraph imaging telescope.

Posted in: Application Briefs, Optical Components, Optics, Mirrors, Optics
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Holographic Plossl Retroreflectors

Lightweight, inexpensive holographic optical elements would be used in place of lenses.

Holographic retroreflectors that function equivalently to Plossl eyepieces have been developed and used in free-space optical communication systems that utilize laser beams. Plossl eyepieces are well known among telescope designers. They have been adopted for use as retroreflectors and as focusing elements (for reception) and collimating elements (for transmission) in optical communication systems. A retroreflector that incorporates a Plossl eyepiece is termed a cat’s eye retroreflector (see figure).

Posted in: Briefs, TSP, ptb catchall, Tech Briefs, Photonics, Lasers, Optics, Telecommunications
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High-Speed Laser Scanner Maps a Surface in Three Dimensions

Surface flaws can be scanned automatically and displayed in real time.

A scanning optoelectronic instrument generates the digital equivalent of a three-dimensional (X,Y,Z) map of a surface that spans an area with resolution on the order of 0.005 in. (≈0.125mm). Originally intended for characterizing surface flaws (e.g., pits) on space-shuttle thermal-insulation tiles, the instrument could just as well be used for similar purposes in other settings in which there are requirements to inspect the surfaces of many objects. While many commercial instruments can perform this surface-inspection function, the present instrument offers a unique combination of capabilities not available in commercial instruments.

Posted in: Briefs, TSP, ptb catchall, Tech Briefs, Photonics, Measurements, Lasers, Optics, Inspections
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MALDI and Biotech Push Nitrogen Laser Development

The nitrogen laser is experiencing new growth due to low cost and the MALDI technique.

The Matrix Assisted Laser Desorption and Ionization (MALDI) technique in 1987 led to a renewed interest for the nitrogen laser. MALDI allows large and fragile biomolecules to be desorbed and ionized intact, or with much less fragmentation. The technique increased the upper mass limit for mass spectrometric analyses of biomolecules to over 300,000 Da, and has enabled the analysis of large biomolecules by mass spectrometry to become easier and more sensitive.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics, Lasers
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Electro-Optical Imaging Fourier-Transform Spectrometer

Size, weight, and vibration are reduced by eliminating moving parts.

An electro-optical (E-O) imaging Fourier-transform spectrometer (IFTS), now under development, is a prototype of improved imaging spectrometers to be used for hyperspectral imaging, especially in the infrared spectral region. Unlike both imaging and non-imaging traditional Fourier-transform spectrometers, the E-O IFTS does not contain any moving parts. Elimination of the moving parts and the associated actuator mechanisms and supporting structures would increase reliability while enabling reductions in size and mass, relative to traditional Fourier-transform spectrometers that offer equivalent capabilities. Elimination of moving parts would also eliminate the vibrations caused by the motions of those parts.

Posted in: Briefs, TSP, ptb catchall, Tech Briefs, Photonics, Imaging and visualization, Test equipment and instrumentation
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