12 research outputs found
Sub-Pixel Response Measurement of Near-Infrared Sensors
Wide-field survey instruments are used to efficiently observe large regions
of the sky. To achieve the necessary field of view, and to provide a higher
signal-to-noise ratio for faint sources, many modern instruments are
undersampled. However, precision photometry with undersampled imagers requires
a detailed understanding of the sensitivity variations on a scale much smaller
than a pixel. To address this, a near-infrared spot projection system has been
developed to precisely characterize near-infrared focal plane arrays and to
study the effect of sub-pixel non uniformity on precision photometry.
Measurements of large format near-infrared detectors demonstrate the power of
this system for understanding sub-pixel response.Comment: 9 pages, 13 figures, submitted to PAS
Sub-wavelength terahertz beam profiling of a THz source via an all-optical knife-edge technique
Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors as security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane. A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique. Remarkably, and in spite of the fact that the proposed approach does not require any mechanical probe, such as tips or apertures, we are able to demonstrate the imaging of a terahertz source with deeply sub-wavelength features (<30 μm) directly in its emission plane