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  • Instrumentation and Photography
  • 2000-2004  (166)
  • 2000  (166)
  • 1
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    Photogrammetry of the Map Instrument in a Cryogenic Vacuum Environment (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-10-11
    Description: MAP Instrument requirements dictated that the instruments Focal Plane Assembly (FPA) and Thermal Reflector System (TRS) maintain a high degree of structural integrity at operational temperatures (〈 50K). To verify integrity at these extremes, an elaborate test fixture was constructed to provide a large cryogenic (〈 20K) radiative environment and a mobile photogrammetry camera. This paper will discuss MAP's Instrument requirements, how those requirements were verified using photogrammetry, and the test setup used to provide the environment and camera movement needed to verify the instrument's requirements.
    Keywords: Instrumentation and Photography
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  • 2
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    Computer-implemented method and apparatus for autonomous position determination using magnetic field data (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: A computer-implemented method and apparatus for determining position of a vehicle within 100 km autonomously from magnetic field measurements and attitude data without a priori knowledge of position. An inverted dipole solution of two possible position solutions for each measurement of magnetic field data are deterministically calculated by a program controlled processor solving the inverted first order spherical harmonic representation of the geomagnetic field for two unit position vectors 180 degrees apart and a vehicle distance from the center of the earth. Correction schemes such as a successive substitutions and a Newton-Raphson method are applied to each dipole. The two position solutions for each measurement are saved separately. Velocity vectors for the position solutions are calculated so that a total energy difference for each of the two resultant position paths is computed. The position path with the smaller absolute total energy difference is chosen as the true position path of the vehicle.
    Keywords: Instrumentation and Photography
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  • 3
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    The Preflight Photometric Calibration of the Extreme-Ultraviolet Imaging Telescope EIT (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-08-26
    Description: This paper presents the preflight photometric calibration of the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO). The EIT consists of a Ritchey-Chretien telescope with multilayer coatings applied to four quadrants of the primary and secondary mirrors, several filters and a backside-thinned CCD detector. The quadrants of the EIT optics were used to observe the Sun in 4 wavelength bands that peak near 171, 195, 284, and 304 . Before the launch of SOHO, the EIT mirror reflectivities, the filter transmissivities and the CCD quantum efficiency were measured and these values are described here. The instrumental throughput in terms of an effective area is presented for each of the various mirror quadrant and filter wheel combinations. The response to a coronal plasma as a function of temperature is also determined and the expected count rates are compared to the count rates observed in a coronal hole, the quiet Sun and an active region.
    Keywords: Instrumentation and Photography
    Type: AD-A529688 , Solar Physics; 195; 13-44
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  • 4
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    Miniature micromachined quadrupole mass spectrometer array and method of making the same (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: The present invention provides a quadrupole mass spectrometer and an ion filter for use in the quadrupole mass spectrometer. The ion filter includes a thin patterned layer including a two-dimensional array of poles forming one or more quadrupoles. The patterned layer design permits the use of very short poles and with a very dense spacing of the poles, so that the ion filter may be made very small. Also provided is a method for making the ion filter and the quadrupole mass spectrometer. The method involves forming the patterned layer of the ion filter in such a way that as the poles of the patterned layer are formed, they have the relative positioning and alignment for use in a final quadrupole mass spectrometer device.
    Keywords: Instrumentation and Photography
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  • 5
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    Higher Pole Linear Traps for Atomic Clock Applications (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: We investigate experimentally and theoretically higher pole linear ion traps for frequency standard use. We have built a 12-pole trap and have successfully loaded ions into it from a linear quadrupole trap. By solving the Boltzmann equation describing large ion clouds where space charge interactions are important, we show that clock frequency changes due to ion number fluctuations are much smaller in ion clocks based multipole traps than comparable clocks based on quadrupole linear traps.
    Keywords: Instrumentation and Photography
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  • 6
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    Analysis and Enhancement of Low-Light-Level Performance of Photodiode-Type CMOS Active Pixel Images Operated with Sub-Threshold Reset (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: Noise in photodiode-type CMOS active pixel sensors (APS) is primarily due to the reset (kTC) noise at the sense node, since it is difficult to implement in-pixel correlated double sampling for a 2-D array. Signal integrated on the photodiode sense node (SENSE) is calculated by measuring difference between the voltage on the column bus (COL) - before and after the reset (RST) is pulsed. Lower than kTC noise can be achieved with photodiode-type pixels by employing "softreset" technique. Soft-reset refers to resetting with both drain and gate of the n-channel reset transistor kept at the same potential, causing the sense node to be reset using sub-threshold MOSFET current. However, lowering of noise is achieved only at the expense higher image lag and low-light-level non-linearity. In this paper, we present an analysis to explain the noise behavior, show evidence of degraded performance under low-light levels, and describe new pixels that eliminate non-linearity and lag without compromising noise.
    Keywords: Instrumentation and Photography
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  • 7
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    Time-resolved diffusion tomographic 2D and 3D imaging in highly scattering turbid media (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: wherein W is a matrix relating output at source and detector positions r.sub.s and r.sub.d, at time t, to position r, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, 〈nn〉to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =〈nn〉/〈.DELTA.Xj.DELTA.Xj〉 Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absorption information. An algorithm, which combines a two dimensional (2D) matrix inversion with a one-dimensional (1D) Fourier transform inversion is used to obtain images of three dimensional hidden objects in turbid scattering media.
    Keywords: Instrumentation and Photography
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  • 8
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    Microscope using micro-channel filter (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: A microscope formed from an image sensor placed against a microchannel filter so that there is one to one correspondence between the sample and the sensor, effectively enlarging the image.
    Keywords: Instrumentation and Photography
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  • 9
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    Temperature Stabilization Requirements for Unchopped Thermal Detectors (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: The temperature stabilization requirements of unchopped thermistor bolometers and thermopile detectors are analyzed. The detector temperature, on which the bolometer output signal depends, is quite sensitive to changes in instrument temperature but relatively insensitive to changes in scene temperature. In contrast, the difference in temperature between detector and substrate (instrument), on which the thermopile signal depends, is equally sensitive to changes in instrument and scene temperature. Expressions for these dependencies are derived based on a simplified instrument model. It is shown that for a typical uncooled thermal imager, the temperature stabilization requirements for a bolometer are two orders of magnitude more stringent than those for a thermopile detector. Keywords: thermistor, bolometer, thermopile, detector, IR, thermal, temperature stabilization
    Keywords: Instrumentation and Photography
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  • 10
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    Intercomparison of Laboratory Radiance Calibration Standards (2000)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: Several standards for radiometric calibration were measured repeatedly with a spectroradiometer in order to understand how they compared in accuracy and stability. The tested radiance standards included a NIST 1000 W bulb and halon panel, two calibrated and stabilized integrating spheres, and a cavity blackbody. Results indicate good agreement between the blackbody and 1000 W bulb/spectralon panel, If these two radiance sources are assumed correct, then the integrating spheres did not conform. to their manufacturer-reported radiances in several regions of the spectrum. More detailed measurements am underway to investigate the discrepancy.
    Keywords: Instrumentation and Photography
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