For the application of high repetition rate WDM pulse train generation from a femtosecond modelocked fiber laser, the direct space-to-time pulse shaper and a properly designed arrayed waveguide grating (AWG) are equivalent. The analogy between the bulk optics and integrated configuration is explored for this application. The critical design parameters of the AWG are the free spectral range and ...

We describe the effects of baseline ripple in an airborne submillimeter wave radiometer, which are caused by standing waves in the quasi-optical path. These baselines can be reduced with an improvement of the calibration loads and with a pathlength modulator. We have modelled the impact of the baseline on the retrieval of the volume mixing ratio profiles of the atmospheric constituents and we w...

We report the first application of a thermoelectrically cooled, distributed-feedback quantum-cascade laser for continuous spectroscopic monitoring of CO in ambient air at a wavelength of 4.6 microm. A noise-equivalent detection limit of 12 parts per billion was demonstrated experimentally with a 102-cm optical pathlength and a 2.5-min data acquisition time at a 10-kHz pulsed-laser repetition ra...

The graph-navigability problem concerns how one can find as short paths as possible between a pair of vertices, given an incomplete picture of a graph. We study the navigability of graphs where the vertices are tagged by a number (between 1 and the total number of vertices) in a way to aid navigation. This information is too little to ensure errorfree navigation but enough, as we will show, for...

The Space Interferometry Mission (SIM) is a space-based long-baseline optical interferometer for precision astrometry. One of the primary objectives of the SIM instrument is to accurately determine the directions to a grid of stars, together with their proper motions and parallaxes, improving a priori knowledge by nearly three orders of magnitude. The basic astrometric observable of the instrum...

Two near-infrared spectroscopy (NIRS) methods are available for measuring changes (Delta) in total cerebral hemoglobin concentration (CHC): 1) a continuous measurement of the changes in total hemoglobin concentration (Delta[Hb]tot) and 2) the difference between two absolute measurements of CHC, each derived from a small, controlled change in inspired O2 fraction. This paper investigates the int...

Functional near-infrared spectroscopy (fNIRS) in brain imaging needs to be robust subject-wise variability. The use of a fixed differential pathlength factor (DPF) per wavelength for the entire will degrade accuracy hemodynamic responses. Since tissue composition varies within brain, correct DPF values should used various emitter-detector distances and regions. In this article, estimation metho...