A new generation of hollow waveguide (HWG) gas cells of unprecedented compact dimensions facilitating low sample volumes suitable for broad- and narrow-band mid-infrared (MIR; 2.5-20 μm) sensing applications is reported: the substrate-integrated hollow waveguide (iHWG). iHWGs are layered structures providing light guiding channels integrated into a solid-state substrate material, which are competitive if not superior in performance to conventional leaky-mode fiber optic silica HWGs having similar optical pathlengths. In particular, the provided flexibility in device and optical design and the wide variety of manufacturing strategies, substrate materials, access to the optical channel, and optical coating options highlight the advantages of iHWGs in terms of robustness, compactness, and cost-effectiveness. Finally, the unmatched modularity of this novel waveguide approach facilitates tailoring iHWGs to almost any kind of gas sensor technology providing adaptability to the specific demands of a wide range of sensing scenarios. Device fabrication is demonstrated for the example of a yin-yang-shaped gold-coated iHWG fabricated within an aluminum substrate with a footprint of only 75 mm × 50 mm × 12 mm (L × W × H), yet providing a nominal optical absorption path length of more than 22 cm. The analytical utility of this device for advanced MIR gas sensing applications is demonstrated for the gaseous constituents butane, carbon dioxide, cyclopropane, isobutylene, and methane.

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The Ozone Mapping and Profiler Suite (OMPS) is being developed for the United States National Polar-orbiting Operational Environmental Satellite System (NPOESS). We describe the optical design and predict the performance of the OMPS nadirlooking imaging spectrometer. Backscattered solar ultraviolet radiation is dispersed and measured to determine the ozone total column amounts and profile concentrations. The sensor consists of a wide field (110 degree) telescope, with a solardiffuser calibration mechanism, and two spectrometers: an imager covering 300 to 380 nm with a 50 km nadir footprint for mapping total column ozone across a 2800 km swath, and a 250 to 310 nm spectrometer with a single 250 km footprint to provide ozone profile data with SBUV/2 heritage. Both spectrometers provide 1 nm resolution (full-width at half-maximum, FWHM) spectra and handle the demanding dynamic range of the backscattered solar radiation with the required sensitivity for ozone retrievals.

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Abstract. The designs of two imaging freeform systems using nonuniform rational basis-spline (NURBS) optical surfaces are described. The first system, a 10 deg ×9 deg f ∕2 three-mirror anastigmat has four times higher spatial resolution over the image plane compared with the equivalent conventional rotational aspheric design, and 2.5 times higher resolution compared with a 10th-order X Y polynomial freeform design. The mirrors for the NURBS freeform design have more than twice the asphericity than the conventional rotational and X Y polynomial designs. In the second system, a Ritchey-Chretien telescope followed by a two-mirror NURBS freeform corrector is compared to a four-mirror Korsch telescope, for imaging to a visible-infrared imaging spectrometer. The freeform corrector design had 70% smaller spot sizes over the field and eliminated the large tertiary required in Korsch type design. Both of these NURBS freeform designs are possible due to a custom optical design code for fast accurate NURBS optimization, which now has parallel raytracing for thousands of NURBS grid points.

The National Ignition Facility's full-aperture backscatter station (FABS) is described. The FABS uses five independent diagnostics on each of the four laser beams in the initial National Ignition Facility quad to measure the energy, power, spectrum, and near-field amplitude modulations of the stimulated Brillouin and stimulated Raman backscattered light. In initial tests CO 2 and C 5 H 12 gas-filled targets were used to create various laser-plasma interaction conditions which have shown the capability of producing ignition size laser plasmas with reflectivites on the order of 10%. Results are presented for tests in which 16 kJ on target produced between 0.3 and 2.5 kJ of backscattered light.

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Grayscale lithography is a widely known but underutilized microfabrication technique for creating three-dimensional (3-D) microstructures in photoresist. One of the hurdles for its widespread use is that developing the grayscale photolithography masks can be time-consuming and costly since it often requires an iterative process, especially for complex geometries. We discuss the use of PROLITH, a lithography simulation tool, to predict 3-D photoresist profiles from grayscale mask designs. Several examples of optical microsystems and microelectromechanical systems where PROLITH was used to validate the mask design prior to implementation in the microfabrication process are presented. In all examples, PROLITH was able to accurately and quantitatively predict resist profiles, which reduced both design time and the number of trial photomasks, effectively reducing the cost of component fabrication.