Improving costs and scale reflect looming opportunities

Coordinating technology, policy, and business innovations

ABSTRACT. We describe the data reduction algorithms for the Multiband Imaging Photometer for Spitzer (MIPS). These algorithms were based on extensive preflight testing and modeling of the Si:As (24 mm) and Ge:Ga (70 and 160 mm) arrays in MIPS and have been refined based on initial flight data. The behaviors we describe are typical of state-of-the-art infrared focal planes operated in the low backgrounds of space. The Ge arrays are bulk photoconductors and therefore show a variety of artifacts that must be removed to calibrate the data. The Si array, while better behaved than the Ge arrays, does show a handful of artifacts that must also be removed to calibrate the data. The data reduction to remove these effects is divided into three parts. The first part converts the nondestructively read data ramps into slopes while removing artifacts with time constants of the order of the exposure time. The second part calibrates the slope measurements while removing artifacts with time constants longer than the exposure time. The third part uses the redundancy inherent in the MIPS observing modes to improve the artifact removal iteratively. For each of these steps, we illustrate the relevant laboratory experiments or theoretical arguments, along with the mathematical approaches taken to calibrate the data. Finally, we describe how these preflight algorithms have performed on actual flight data.

No abstract

Cathodoluminescence (CL) is the emission of light from a material in response to excitation by incident electrons. The technique has had significant impact in the characterization of semiconductors, minerals, ceramics, and many nanostructured materials. Since 2010, there have been a number of innovative developments that have revolutionized and expanded the information that can be gained from CL and broadened the areas of application. While the primary historical application of CL was for spatial mapping of luminescence variations (e.g., imaging dark line defects in semiconductor lasers or providing high resolution imaging of compositional variations in geological materials), new ways to collect and analyze the emitted light have expanded the science impact of CL, particularly at the intersection of materials science and nanotechnology. These developments include (1) angular and polarized CL, (2) advances in time resolved CL, (3) far-field and near-field transport imaging that enable drift and diffusion information to be obtained through real space imaging, (4) increasing use of statistical analyses for the study of grain boundaries and interfaces, (5) 3D CL including tomography and combined work utilizing dual beam systems with CL, and (6) combined STEM/CL measurements that are reaching new levels of resolution and advancing single photon spectroscopy. This focused review will first summarize the fundamentals and then briefly describe the state-of-the-art in conventional CL imaging and spectroscopy. We then review these recent novel experimental approaches that enable added insight and information, providing a range of examples from nanophotonics, photovoltaics, plasmonics, and studies of individual defects and grain boundaries.