When
3:30 p.m., June 11, 2012
Where
Kuiper Space Sciences 308
Dr. Walter Harris
Associate Professor
University of California, Davis
"Development of Spatial Heterodyne Spectroscopy for Line-resolved Remote Sensing of Wide-field Astrophysical Phenomena"
Abstract:
High-resolution spectroscopy is an important remote sensing tool for studies of the energetic and dynamic universe on all scales. From line shapes and Doppler shifts we gain access to parameters such as velocity distributions, temperature/pressure, molecular bands, radiative transfer and the separation of multiple sources. Unfortunately, many grating spectrograph designs are a poor technical match to the study of faint (e.g. airglow), extended (e.g. the interstellar medium), and low-energy (e.g. planetary atmospheres) targets, particularly those observable only from space or with structure (temporal or spatial) that requires many observations to characterize. Large aperture telescope-spectrometer combinations can provide the necessary sensitivity for these targets, but they typically sample small fields of view, are difficult to schedule for large campaigns, and their size makes their use on in situ remote probes impractical. Interferometry is an alternative technique that can provide high-sensitivity on wide-field targets, but these instruments are often limited in their wavelength coverage and by opto-mechanical tolerances that are difficult to maintain at short wavelengths. In this presentation I will discuss progress in the development of an all-reflective spatial heterodyne spectrometer (SHS), a type of wide-field interferometer with relaxed optical tolerances and broadband capability that is compact enough to use in space or at meter-class observatories. In particular, I will describe the design and initial results of a narrow band vacuum SHS sounding rocket experiment and two broadband SHS implementations that are capable of sampling up to a decade in wavelength across the ultraviolet and visible spectral range.
Associate Professor
University of California, Davis
"Development of Spatial Heterodyne Spectroscopy for Line-resolved Remote Sensing of Wide-field Astrophysical Phenomena"
Abstract:
High-resolution spectroscopy is an important remote sensing tool for studies of the energetic and dynamic universe on all scales. From line shapes and Doppler shifts we gain access to parameters such as velocity distributions, temperature/pressure, molecular bands, radiative transfer and the separation of multiple sources. Unfortunately, many grating spectrograph designs are a poor technical match to the study of faint (e.g. airglow), extended (e.g. the interstellar medium), and low-energy (e.g. planetary atmospheres) targets, particularly those observable only from space or with structure (temporal or spatial) that requires many observations to characterize. Large aperture telescope-spectrometer combinations can provide the necessary sensitivity for these targets, but they typically sample small fields of view, are difficult to schedule for large campaigns, and their size makes their use on in situ remote probes impractical. Interferometry is an alternative technique that can provide high-sensitivity on wide-field targets, but these instruments are often limited in their wavelength coverage and by opto-mechanical tolerances that are difficult to maintain at short wavelengths. In this presentation I will discuss progress in the development of an all-reflective spatial heterodyne spectrometer (SHS), a type of wide-field interferometer with relaxed optical tolerances and broadband capability that is compact enough to use in space or at meter-class observatories. In particular, I will describe the design and initial results of a narrow band vacuum SHS sounding rocket experiment and two broadband SHS implementations that are capable of sampling up to a decade in wavelength across the ultraviolet and visible spectral range.
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LPL Colloquium
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