Karen E. Yokoyama

Robust superconducting die attach process

As complexity of superconducting digital systems increase, the need for multi-chip modules and a reliable, high bandwidth attachment scheme for superconducting die becomes more and more critical. We have developed a flip chip die attach process for Low Temperature Superconducting (LTS) chips using InSn reflow soldering. Using standard reflow techniques, we create highly reproducible, uniform 14 micron-high solder bumps on gold-defined pad regions. Subsequent alignment, compression, and reflow soldering produce reliable, low inductance connections with high yield. The short interconnect distance of 5-7 /spl mu/m results in low enough inductance to support multi-GHz chip interconnect at low impedance. We have successfully tested and thermally cycled flip chipped die over many temperature cycles to liquid helium temperatures with no failures. We will report on successful attachment, testing, and rework of superconducting circuit chips. Specifically, we present data on solder bump uniformity, yield, electrical and thermal characteristics, reworkability, and reliability under repeated thermal cycling.

Radiometric calibration transfer chain from primary standards to the end-to-end Hyperion sensor

This paper describes the calibration transfer path from primary standards representing fundamental physical quantities through the calibration radiance source used in Hyperion instrument level absolute calibration. The calibration transfer path and hardware design of the primary and secondary standards and their validation for end-to-end calibration of the sensor are presented. The primary standards reside at the TRW Radiometric Scale Facility and include two high quantum efficiency Silicon photodiode trap detectors; an electrically self-calibrated pyroelectric detector serves as a secondary standard for crosscheck. The end-to-end sensor calibration is accomplished with a Calibration Panel Assembly (CPA) source, which is illuminated by a NIST traceable FEL 1000 transfer standard lamp. An independent crosscheck of the Spectralon reflectance properties is made with a transfer radiometer. An error analysis of the transfer path is presented. The basic strategy of the Hyperion end-to-end calibration is to reduce the size of the sensor responsivity error tree and to provide control of systematic errors as much as possible through cross-calibration.

Passive millimeter-wave video camera

A passive millimeter-wave (PMMW) camera capable of generating a real time display of the imaged scene, similar to video cameras, has been developed at TRW and is undergoing field testing. The camera operates at 89 GHz, acquiring images at a frame rate of 17 Hz. This work reports on the video imaging generated by the camera. This research is carried out under the Passive Millimeter-Wave Camera Consortium, a cost-shared program between the Defense Advanced Research Programs Agency and an industrial consortium that includes Honeywell, McDonnell Douglas and TRW. It is managed for the Department of Defense by NASA-LaRC.

On-orbit solar radiometric calibration of the Hyperion instrument

The end-to-end calibration plan for the Hyperion EO-1 hyperspectral payload is presented. The ground calibration is traceable to a set of three high quantum efficiency p-n silicon photodiode trap detectors the responsivities of which are traceable absolutely to solid state silicon diode physical laws. An independent crosscheck of the radiance of the Calibration Panel Assembly used to flood the Hyperion instrument in field and aperture was made with a transfer radiometer developed at TRW. On-orbit measurements of the suns irradiance as it illuminates a painted panel inside the instrument cover are compared to the radiance scale developed during pre-flight calibration. In addition, an on-orbit calibration lamp source is observed to trace the pre-flight calibration constants determined on the ground to the solar calibration determination.

NGST longwave hyperspectral imaging spectrometer system characterization and calibration

Northrop Grumman Space Technology (NGST) has developed and tested a Long-wave Hyperspectral Imaging Spectrometer (LWHIS) that operates in the 8 to 12.5 micron band. An overview of the system design has been described elsewhere. This paper describes the system characterization and radiometric calibration of this instrument using NGST’s Long-wave Hyperspectral Test Facility which uses a 1375K globar source assembly, a monochromator, a collimator and a fine pointing mirror to provide image quality and FPA alignment data. Image quality characterization results presented here include measurement of the instrument’s Modulation Transfer Function (MTF), spatial co-registration of spectral channels (spectral smile), cross-track spectral error (spatial smile), and spectral calibration. Radiometric calibration results for laboratory targets are also presented.

Demonstration of a series array interferometer logic (SAIL) superconductive digital circuit

TRW is developing High Temperature Superconducting (HTS) electronics to dramatically improve the performance of space- based communications systems. These systems demand high speed analog-to-digital converters, high speed digital multiplexers, and quadriphase modulation of rf carrier signals. TRW has demonstrated an HTS high-speed multiplexer and a digital phase modulator that operates at microwave frequencies. The latter is the fundamental building block of a Quadriphase Modulator Exciter (QME). TRW has also developed an HTS cryogenic packaging subsystem which uses a commercially available palm-sized cryocooler. This package represents the first demonstration of an HTS self-supporting system. Package verification tests revealed that the package is capable of supporting high speed I/O and demonstrates reliable connectivity through multiple interfaces. The successful operation of a digital phase modulator has been demonstrated with this package.