The ARCSTONE project objective is to acquire accurate measurements of the spectral lunar reflectance from space, allowing the Moon to be used as a high-accuracy SI-traceable calibration reference by spaceborne sensors in low-Earth and geostationary orbits. The required spectral range is 350 to 2300 nm with 4-nm sampling. The ARCSTONE approach is to measure solar and lunar spectral irradiances with a single set of optics and determine spectrally resolved lunar reflectances via a direct ratioing method, eliminating long-term optical degradation effects. Lunar-irradiance values, derived from these direct reflectance measurements, are enabled by independently measured SI-traceable spectral solar irradiances, essentially using the Sun as an on-orbit calibration reference. In an initial attempt to demonstrate this approach, a prototype ultraviolet-visible-near infrared (348 to 910 nm) instrument was designed, fully assembled, characterized, and field tested. Our results demonstrate that this prototype ARCSTONE instrument provides a dynamic range larger than 106, which is necessary to directly measure both the solar and lunar signals, and suggest uncertainties better than 0.5% (k = 1) in measuring lunar spectra can be achieved under proper operational scenarios. We present the design, characterization, and proof-of-concept field-test of the ARCSTONE instrument prototype.
The Emirates Mars Mission (EMM) UV Spectrograph (EMUS) is a far ultraviolet (102 nm to 170 nm) imaging spectrograph for characterization of the Martian exosphere and thermosphere. Imaging is accomplished by a photon counting open-face microchannel plate (MCP) detector using a cross delay line (XDL) readout. An MCP gain stabilization (“scrub”) followed by lifetime spectral line burn-in simulation has been completed on a bare MCP detector at SSL. Gain and sensitivity stability of better than 7% has been demonstrated for total dose of 2.5 × 1012 photons cm−2 (2 C · cm−2 ) at 5.5 kHz mm−2 counting rates, validating the efficacy of an initial low gain full-field scrub.
Monocular architecture is an attractive candidate for a consumer drive. A raw data density of 712Gbits/inch2 was
achieved using this architecture with a blue laser and a high NA objective lens.
The media position and tilt tolerances of a high numerical aperture (NA) holographic
data storage system are examined experimentally. The sources for these tolerances are explained
and techniques for optimizing the drive tolerances are described.
KEYWORDS: LIDAR, Crystals, Sensors, Signal detection, Holography, Modulation, Laser crystals, Signal processing, High power lasers, Pulsed laser operation
We introduce a new approach to coherent LIDAR remote sensing by utilizing a quantum-optical, parallel sensor based on spatial-spectral holography (SSH) in a cryogenically cooled inhomogeneously-broadened absorber (IBA) crystal that is used to sense the LIDAR returns and perform the front-end range-correlation signal processing. This SSH sensor increases the LIDAR system sensitivity through range-correlation gain before detection. This approach permits the use of high-power, noisy, CW lasers as ranging waveforms in LIDAR systems instead of the highly stabilized, injection seeded and amplified pulsed laser sources required by most coherent LIDAR systems. The capabilities of the IBA media for many 10s of GHz bandwidth and sub-MHz resolution, while using either a coded waveform or just a high-power, noisy laser with a broad linewidth (e.g. a random noise LIDAR) may enable a new generation of improved LIDAR sensors and processors. Preliminary experimental demonstrations of LIDAR range detection and signal processing for random noise and chirped transmitted waveforms are presented.
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