Wide-field collimators for spectrographs

Astrometric demands of fibre-input spectrographs for wide-field quasar redshift surveys

A potential problem with using wide-field multi-object spectrographs for quasar redshift surveys is the introduction of positiondependent selection effects into the survey catalogue because of variations in the observed signal-to-noise ratio (SNR) across the survey area. A function relating signal losses in instruments using optical fibre input to the fibre-to-image position error, the fibre di...

Integral Field Spectrographs: a user’s view

We easily tend to think of Integral-Field Spectrographs (IFS) along two opposing trends: as either the beautiful combination between photometry and spectroscopy, or as our worst nightmare including the dark side of both worlds. I favour a view where each IFS is considered individually, as one instrument with specific performances which can be used optimally for a certain range of scientific pro...

Algorithms for Sequencing Multileaf Collimators

Flash spectrographs for FEL diagnostics and XANES measurements at LCLS

This proposal aims to continue the preliminary experiments using SPPS, which demonstrated the feasibility of preforming XANES experiments on the femtosecond time scale. It also has the potential to provide a shot-by-shot measurement of the beam spectral profile. The instrument consists of a simple dispersive spectrometer coupled to an integrating position-sensitive detector. Experiments at NSLS...

Miniature Spectrographs: Characterization of Arrayed Waveguide Gratings for Astronomy

We present results from a laboratory characterization of integrated photonic arrayed-waveguide grating chips, which are a modified version of commercial arrayed-waveguide grating multiplexors, for the purposes of creating an integrated photonic spectrograph. Using a robust probing setup we measure the peak total efficiency of the chips to be ~75%. We measure the spectral resolution full-width h...