James S. Vickers

Self-compensating, all-reflection interferometer

A grating interferometer that uses all-reflecting optical components has been developed for operation in the extreme and far UV. The instrument uses a V-groove, ruled grating as its beam splitter and has no moving parts. A self-compensating optical design is employed that makes it tolerant to small misadjustments of optical alignments and convenient for space-flight applications. The instrument described here uses a 600-groove/mm plane diffraction grating that operates in the second order and obtains a resolving power of ~ 100,000 at 1216 Å.

Interplanetary H Lyα Observations from a Sounding Rocket

We describe a Self-Compensating All-Reflecting Interferometer used to measure diffuse interplanetary H Ly? emission (? ~ 1216 ?) of interstellar origin at high spectral resolution (?/?? ~ 100,000). The instrument is capable of resolving the separation between the Doppler-shifted, interplanetary neutral H emission from the Earths geocoronal emission line. We present the optical layout and mechanical design that enable the instrument to maintain alignment through a sounding rocket flight. We find an H Ly? spectrum, including both geocoronal emission and interplanetary scattered features, which we have fitted using Gaussian line profiles. The interplanetary H line is fitted with a 7900 ? 2400 K line width. The geocoronal line width is fitted with a 1900 ? 500 K Gaussian. The Doppler shift between the geocoronal and interplanetary line is 0.145 ?, corresponding to an apparent interplanetary wind velocity of 16 ? 7 km s-1. We show how full line-profile measurements of interplanetary H emission can advance current studies of the heliospheric interface region and very local interstellar medium.

Silicon-anode detector with integrated electronics for microchannel-plate imaging detectors

We describe a silicon anode with integrated electronics for use in photon-counting microchannel-plate (MCP) imaging detectors. Very-large-scale integrated techniques using a 2 μm complementary metal–oxide–semiconductor (CMOS) process allow a passive-anode region, which collects charge from the MCPs, to be surrounded by an active event-processing region. The anode region is made from a rectangular array of pads that are formed using the metal interconnect layers of the CMOS process. Individual pads are electrically connected to form isolated arrays of rows and columns; each row terminates at a well of one charge-coupled device (CCD) register, and each column terminates at a well of a second orthogonal CCD register. The distribution of charge within each register is used to encode the charge-cloud coordinates. A two-dimensional prototype anode was constructed with 128×80 pixels spaced at 50 μm intervals; the anode readout rate is 31 250 Hz. Subpixel centroiding techniques can be employed to reduce the numbe...

Tomographic extreme-ultraviolet spectrographs: TESS

We describe the system of Tomographic Extreme Ultraviolet (EUV) SpectrographS (TESS) that are the primary instruments for the Tomographic Experiment using Radiative Recombinative Ionospheric EUV and Radio Sources (TERRIERS) satellite. The spectrographs were designed to make high-sensitivity {80 counts/s)/Rayleigh [one Rayleigh is equivalent to 10(6) photons/(4pi str cm(2)s)}, line-of-sight measurements of the oi 135.6- and 91.1-nm emissions suitable for tomographic inversion. The system consists of five spectrographs, four identical nightglow instruments (for redundancy and added sensitivity), and one instrument with a smaller aperture to reduce sensitivity and increase spectral resolution for daytime operation. Each instrument has a bandpass of 80-140 nm with approximately 2- and 1-nm resolution for the night and day instruments, respectively. They utilize microchannel-plate-based two-dimensional imaging detectors with wedge-and-strip anode readouts. The instruments were designed, fabricated, and calibrated at Boston University, and the TERRIERS satellite was launched on 18 May 1999 from Vandenberg Air Force Base, California.

Improved radio tomography of the ionosphere using EUV/optical measurements from satellites

Computerized tomography of the ionosphere employs radio beacons on satellites and ground-based receivers that measure the integrated electron densities along line-of-sight propagation paths. The primary limitation to satellite-based ionospheric radio tomography is the lack of near-horizontal ray paths. This restricts the accuracy for the reconstruction of vertical profiles in the F region. Horizontal integration paths may be obtained using the natural extreme ultraviolet emissions in the ionosphere. The emissions at 91.1 nm are the result of radiative recombination of O+ ions and electrons and at 83.4 nm are produced by photoionization of atomic oxygen and subsequent scatter by the atomic oxygen ion. Combining data from radio and EUV measurements yields greatly improved ionospheric density reconstructions. This concept will be tested using the TERRIERS satellite scheduled for launch in early 1998.

Gas ionization solar spectral monitor (GISSMO)

We are currently developing an instrument free from optical components to measure the full-disk solar spectrum in the extreme ultraviolet regime covering wavelengths from 75-500 A. The instrument, which will be launched aboard a NASA Black Brant sounding rocket in September 1992, consists of a windowless noble gas ionization cell followed by a toroidal electrostatic analyzer to spatially disperse photoelectrons as a function of their energies. A microchannel plate based position sensitive detector will be used to detect individual electrons, indirectly returning the solar EUV spectrum.

Gas ionization solar spectral monitor

We are currently developing an instrument free from optical components to measure the full-disk solar spectrum in the extreme-ultraviolet (EUV) regime covering wavelengths from 75 to 400A. The instrument consists of a windowless noble gas ionization cell followed by a toroidal electrostatic analyzer to spatially disperse photoelectrons as a function of their energies. A microchannel plate based position sensitive detector is used to detect individual electrons, indirectly returning the solar EUV spectrum. The instrument was launched aboard a NASA Black Brant sounding rocket on October 27, 1992. Power to this instrument was lost early in the flight, however, and a reflight is planned for October 1993. Calibration results for the He II 304-A line are presented.

Performance-based metrology of critical device performance parameters for in-line non-contact high-density intra-die monitor/control on a 32nm SOI advanced logic product platform

We report a strong direct correlation (above 0.9) between conventional transistor-level parametrics typically used in the industry to monitor and control intra-die variability (IDV) and a novel, non-contact performance-based metrology (PBM), technology that was integrated into an active die on a 32nm SOI advanced logic product platform. We demonstrate a PBM test structure measurement repeatability of less than 0.4%. In this work, we also demonstrate the compatibility of integrating the PBM technology into an advanced CMOS process flow with no added processing or steps, as well as its footprint scalability. The data suggests that the non-contact PBM technology meets all prerequisites for its deployment as a standard, within-product IDV monitor.

Instrument design and test results of the new all-reflection spatial heterodyne spectrometer

An all-reflection spatial heterodyne spectrometer (SHS) has been recently developed. The advantages over conventional high-resolution grating spectrometers are that the SHS requires no mechanical scanning, a self-compensating optical design permits easy alignment, and it is much smaller than other spectrometers of comparable resolution. Since all beam-splits and recombinations occur by reflection off of a diffraction grating, the interferometer is capable of operating well into the extreme ultraviolet (EUV) and possibly into the soft X-ray region. A description of the design and the characteristics of the instrument is presented. Also, test results, including sample interferograms as well as their Fourier-transformed spectra, at both visible and UV wavelengths are shown. Finally, we report on future developments and possible applications.