Solid-state Detector Array Research Articles

Optical methods for precision measurements

Contactless measuring techniques are becoming increasingly important for industrial applications. The use of a laser, solid-state detector arrays and powerful small computers leads to a very efficient fringe analysis in holography as well as in Moire and speckle techniques. Due to the computer analysis, much more information can be extracted from interferograms, leading to higher sensitivities and accuracies. The application of different fringe analysis procedures is discussed, together with some potentials of the application of interferometry, holography, and speckle and Moire techniques.

Optical methods for precision measurements

Contactless measuring techniques are becoming increasingly important for industrial applications. The use of a laser, solid-state detector arrays and powerful small computers leads to a very efficient fringe analysis in holography as well as in Moiré and speckle techniques. Due to the computer analysis, much more information can be extracted from interferograms, leading to higher sensitivities and accuracies. The application of different fringe analysis procedures is discussed, together with some potentials of the application of interferometry, holography, and speckle and Moiré techniques.

Properties of the main-sequence eclipsing binary UZ Draconis

view Abstract Citations (9) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Properties of the Main-Sequence Eclipsing Binary UZ Draconis Lacy, Claud H. ; Gulmen, Omur ; Gudur, Necdet ; Sezer, Cengiz Abstract The fundamental properties of the main-sequence binary, UZ Dra, are determined from observational data. Photoelectric radial-velocity measurements (Imbert, 1986), spectroscopic data obtained with solid-state array detectors, and B,V photoelectric light curves of the binary are examined. The properties of the stars in the binary are presented and compared with those of other F-type main-sequence binaries listed by Popper (1980). Publication: The Astronomical Journal Pub Date: March 1989 DOI: 10.1086/115028 Bibcode: 1989AJ.....97..822L Keywords: Eclipsing Binary Stars; Main Sequence Stars; Stellar Evolution; Stellar Spectrophotometry; Light Curve; Line Spectra; Radial Velocity; Spectral Line Width; Astrophysics; STARS: INDIVIDUAL; STARS: ECLIPSING BINARIES full text sources ADS | data products SIMBAD (3)

Digital optical spark chambers

The authors constructed and tested a prototype digital readout system for optical spark chambers using a linear, solid-state charge-coupled detector array. Position resolution of 0.013 mm ( sigma ) over a 25-cm field of view has been demonstrated. It is concluded that this technique should permit the construction of economical, lightweight and low-power trajectory hodoscopes for use in cosmic-ray instrumentation on balloons and in spacecraft.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

GRASP - Gamma Ray Astronomy with Spectroscopy and Positioning

The GRASP telescope, which is currently under assessment by the European Space Agency as a future space mission, is designed to generate high resolution images of the gamma-ray sky with high sensitivity and fine spectral resolution. The telescope employs a coded aperture mask and the capability to function as a Spectral Imager is achieved by the incorporation of an array of discrete aermanium solid state detectors within the matrix of a larger position sensitive CsI(Tl) gamma-ray detection plane.

Measured performance characteristics of a solid‐state linear detector array

Experimental studies of a solid-state linear detector array developed for a prototype scanning slit digital chest radiographic unit have been completed. The detector consists of a strip of scintillating material, optically coupled to a linear silicon photodiode array. Measured performance characteristics of the detector, such as sensitivity, modulation transfer function, and detective quantum efficiency, are presented for several different scintillators. Results indicate that direct x-ray absorption events in the silicon photodiode can degrade detective quantum efficiency. Results also indicate that the inexpensive preamplifier circuits used in the digital chest prototype contribute negligible noise at diagnostic x-ray photon fluence rates.

Two-wavelength phase shifting interferometry

This paper describes a technique that combines ideas of phase shifting interferometry (PSI) and two-wavelength interferometry (TWLI) to extend the phase measurement range of conventional single-wavelength PSI. To verify theoretical predictions, experiments have been performed using a solid-state linear detector array to measure 1-D surface heights. Problems associated with TWLPSI and the experimental setup are discussed. To test the capability of the TWLPSI, a very fine fringe pattern was used to illuminate a 1024 element detector array. Without temporal averaging, the repeatability of measuring a surface having a sag of ~100 μm is better than 25-A (0.0025%) rms.

Charge-Coupled Device Image Acquisition For Digital Phase Measurement Interferometry

Direct phase measurement interferometry can provide a fast and accurate means of obtaining surface data. Solid-state detector arrays are ideal imaging devices for these instruments. These imagers can be coupled to micro-computers for phase calculation. This article discusses the use of CCD arrays and techniques for digitizing and interfacing these arrays to microcomputers.

Single-slit digital radiography: some practical considerations

Clinical evaluation of an experimental digital chest unit using a solid-state linear detector array has provided information regarding the postpatient photon flux required for clinically acceptable images. Results from computer simulation show that energy subtraction imaging of the chest by the method of x-ray-tube voltage switching will be unsuccessful unless it can be demonstrated clinically that a much lower number of photons per pixel is acceptable in energy subtracted images. In addition, x-ray-tube loading limitations preclude imaging of the abdominal and pelvic regions with this technology.

YZ Cas ± 0.5%

I will discuss one of the results of a continuing program to determine accurate masses and radii of stars in eclipsing binaries. This program actually began in 1976 with my work on the faint M-dwarf system CM Dra (Lacy 1977). By faint I mean . I needed high-dispersion spectra to get radial velocities, and an intensified solid state array detector called the Digicon, which had recently been installed on the coude spectrometer of the 2.7m reflector at McDonald Observatory, turned out to be the answer. 30 minute integrations were sufficient to get accurate radial velocities from the Hγ emission lines. The Digicon is very good at getting crumby spectra of faint objects fast. By crumby, I mean signal-to-noise ratio of less than 100.

Optimization of monolithic solid state array detectors for the position encoding of small angle X-ray scattering from synchrotron sources

Several design features of photodiode, charge-coupled, and charge-injection monolithic solid state array detectors that can be utilized for the position encoding of X-ray scattering are discussed. Special emphasis has been placed on their unique applications for the determination of synchrotron small angle X-ray scattering and general considerations for improving performance are presented. The mechanisms of X-ray radiation damage in solid state arrays and their practical consequences for synchrotron radiation are discussed. A small angle diffractometer is described that takes advantage of the high speed and potentially high count rate capabilities of a self-scanning photodiode array to calculate small angle scattering parameters in real time on a millisecond time scale.

An Efficient Faint Object Spectrograph

A faint object spectrograph is described suitable for use with a solid-state detector array. High resolution and low light loss are achieved over a wide spectral range using a cemented assembly of transmission grating, cross-dispersing prism and the corrector plate of a wide aperture camera. Constructional data and performance figures are given.

The direct recording of Raman spectra with solid state detectors

We demonstrate the rapid recording of low noise Raman spectra with an unintensified solid state array detector and a concave holographic grating spectrograph.

New fluorescence detection system for x-ray absorption spectroscopy

The design and performance of a 24-channel fluorescence detection system for use in x-ray absorption spectroscopy are discussed, and comparisons are drawn with other detection systems currently in use. Each channel of the current system consists of a NaI scintillation detector with a filter and collimator arrangement designed to reduce the scatter and filter fluorescence background. Given a sufficiently intense and stable x-ray source, this apparatus can record a useful EXAFS spectrum for an element (Z⩾23) at 100 ppm concentration in approximately 30 minutes. The new design permits the study of plate-like samples (such as molybdenum enzyme solutions) unsuitable for previously described slit assemblies. Breaking the detection system up into discrete elements also allows (1) optimization of filter thickness for each direction, (2) use of a weighting scheme to optimize the total S/N, and (3) operation at high total count rates, while retaining the advantages of pulse counting electronics. The relative merits of filters and crystal monchromators are discussed quantitatively, using the two criteria of efficiency and selectivity. It is shown that practical filters and barrel monochromators give similar performance over a 100-fold concentration range, for a given solid angle, and that the 20-fold solid angle advantage of the multielement approach makes it the design of choice for many cases. Finally, the construction of an array of solid-state detectors with the appropriate filters and collimating elements is proposed as a device capable of yielding unprecedented performance in x-ray absorption spectroscopy.

Solid-state pyroelectric infrared image converter

The following paper outlines a technique for construction of solid-state pyroelectric infrared detector arrays. Four major problems associated with pyroelectric detector arrays in general and solid-state pyroelectric detector arrays in particular are addressed: (1) sensitivity, (2) spatial resolution, (3) heat loading of the substrate and finally (4) a technologically feasible fabrication technique. It is shown that excellent sensitivity and high spatial resolution can be obtained with a combination of a high chopping rate and electronic signal integration in a separate memory. With 100 lp/cm resolution, 50 μm elements, the optimum chopping rate is high enough that there is little or no substrate heat loading effect. Thus, hybrid detector fabrication utilizes technologically simple flip-chip bonding or wire bonding techniques. Calculations based on reports of current performance of CCD multiplexing electronics predict that with electronic signal integration to an equivalent frame rate of 15 Hz and at 100 lp/cm spatial resolution, a minimum resolvable temperature of 0.25°C is achievable. This performance is about a factor of 10 better than the present performance of the state of the art pyroelectric vidicon at the same spatial resolution. A developmental 32 element linear detector array on 4 mil centers with self-scanned FET multiplexing electronics has been constructed. Preliminary array characteristics are reported. The above techniques are patented.

Single photon x-ray detection with a CCD image sensor

Individual x rays of 5.9 and 22.4 keV have been detected and energy analyzed in single pixels of a CCD image sensor. The results indicate the CCD operates as an array of tiny Si solid state detectors providing both high spatial resolution and x-ray energy discrimination. These devices will prove useful sensors at the focus of future x-ray telescopes.

Cadmium Telluride Gamma Camera

A small 4 cm X 4 cm prototype CdTe gamma camera has been constructed which demonstrates sensitivity and spacial resolution superior to the standard Anger camera. The camera is based on an array of linear solid state detectors contained within a laminar collimator which confines the field of view to one dimension. The array is rotated stepwise through 180° and data from each position recorded and computer processed. This technique leads to a major enhancement in sensitivity relative to the multihole collimator. Clinical images have been obtained and a larger CdTe camera is planned.

Spaceborne Astronomy with Electro-Optical Image Sensors

The Space Telescope, planned for orbiting in the early 1980s, is described, with emphasis on its electro-optical image sensing capability. Relative advantages of image tubes and solid state arrays as image detectors are summarized; image tube technology is well characterized, but preference may be given to a more versatile tandem solid state array consisting of one module with high silicon response covering most of the spectrum, and a second intensified array with ultraviolet sensitivity and low noise readout. The classical 'photoelectron noise limit' calculation is reviewed, and a detailed calculation of sensitivity limits adaptable to analysis of image tube or solid state array detectors is also given. In particular, characteristics of a filter to optimize the signal to noise ratio is determined. Typical sensitivity calculations for an image tube detector show that with an exposure of one orbital night (approximately 2000 seconds), 10% photometry may be done to a low limit of visual magnitude.

The charge spectrum of positive ions in a hydrogen aurora

An auroral ion charge spectrometer was flown into a hydrogen aurora on a Javelin sounding rocket launched from Churchill, Manitoba. The instrument contained an electrostatic analyzer which selected particles with incident energy per unit charge up to 20 keV/charge and an 80-kV power supply which accelerated these ions onto an array of solid state detectors. Ions tentatively identified as H(+), He(+2), and O(+) were detected from 225 to 820 km in altitude. The experiment did not discriminate between H(+) and He(+), or between O(+), N(+), and C(+). Upper limits of highly charged heavy ion abundances have been set at 20% of the He(+2) and 0.15% of the H(+). It is concluded that both terrestrial and solar wind sources play significant roles in auroral ion precipitation.

The Facsimile Camera - Its Potential As A Planetary Lander Imaging System

The facsimile camera is an optical-mechanical scanning device which is an attractive candidate for planetary lander imaging systems and has been selected for the Viking/Mars mission because of its light weight, small size, and low power requirement. Other advantages are that it can provide good radiometric and photogrammetric accuracy because the complete field of view is scanned with a single photodetector located on or near the optical axis of the objective lens. In addition, this device has the potential capability of multispectral imaging and spectrometric measurements. This can be implemented without increase in mechanical complexity by the use of interference filters and solid-state detector arrays. Some of these potential capabilities of the facsimile camera have been realized in the Viking Lander Camera design; others are currently being investigated for possible application in future missions. This paper reviews the performance characteristics of the facsimile camera, emphasizing its line-scan sampling process; the design trade offs which are imposed by planetary lander missions, emphasizing those trade offs which define the Viking Lander Camera parameters; and new concepts which are currently being investigated for future planetary lander missions, emphasizing an integrated imagery and spectrometry concept.