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Conference on Advancements in Adaptive Optics

作者： Zappa, F Tisa, S Cova, S Maccagnani, P Bonaccini, D Bonanno, G Belluso, M Saletti, R Roncella, R Politecn Milan Dipartimento Elettr I-20133 Milan Italy

ISBN: (纸本)0819454222

We present the development of silicon monolithic arrays of 60 photon-counters (SPADA, Single-Photon Avalanche Diode array) for the visible. The SPADA system is suitable for state-of-the-art Adaptive Optics operations and Fast Transient image acquisitions, at quite a fraction of the current cost of imaging arrays. The fabricated solid-state photon counters are rugged, easy to be integrated in the optical system. They are free from readout noise and provide very fast frame-rates (>10kHz, for visible corrections) and nanosecond electronic gating (for ranging the up-going laser beam). The detection head has been integrated into an optomechanical system suitable for alignment and focusing in available astrophysics telescopes. The detection electronics includes an integrated Active Quenching Circuits for each pixel of the array. The real-time data processing board is implemented into FPGA and DSP and is configurable for dealing with different applications: the extraction of the curvature wavefront for AO applications, and the acquisition and processing of two-dimensional images with fast frame rate. A remote host computer controls all the SPADA blocks and uploads the processed information and images. We report the optical and electrical characterization of the detectors and the associated electronics.

关键词： SPAD single-photon avalanche diode adaptive optics fast transient phenomena imaging detectors array detectors

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Implications of the sample rate on large space telescopes

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EXPERIMENTAL ASTRONOMY 2001年第3期12卷 179-193页

作者： Fixsen, DJ Cornett, RH NASA Goddard Space Flight Ctr SSAI Greenbelt MD 20771 USA

The frequency at which a large space telescope's (e.g. JWST's) detector chips are read, or the sample rate, is tightly coupled to many hardware and operational aspects of the telescope's instrument and data handling elements. In this paper we discuss many of the drivers and important implications of the sample rate: the data rate to the ground;onboard computer storage, bandwidth, and speed;the number of A-->D chips, and therefore the overall size and power requirements of the analog electronics;cryocabling requirements;and detector noise and power. We discuss and parametrize these and other elements related to sample rate. Finally, we discuss the implications of sample rate in the context of achieving the most important science goals under the constraint of limited cost.

关键词： array detectors IR detectors JWST observation strategies

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Spectroscopic instrumentation in the 21st Century: excitement at the horizon - Plenary lecture

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JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY 1998年第9期13卷 821-827页

作者： Pennebaker, FM Jones, DA Gresham, CA Williams, RH Simon, RE Schappert, MF Denton, MB Univ Arizona Dept Chem Tucson AZ 85721 USA

Recent developments in technology have suggested a promising future for plasma spectroscopy. New optical technologies, such as volume phase technology and unconventional optical systems, when coupled with new generations of optical detectors promise to provide powerful tools for plasma diagnostics or spectrochemical analysis, Nest generation charge injection devices will provide both complete random access of individual detector sites and 'collective readout,' a new readout mode. Collective readout will promise faster readout and improved signal to noise ratios,. A new generation of pre-amp per pixel array detectors with proper addressing architecture will allow random pixel readout and extreme resistance to blooming. These technological advances will yield new capabilities for not only current and future plasma sources, hut also vintage sources such as the microwave-induced plasma, the direct current plasma, direct current are and the direct current spark. Developments in software data processing techniques including neural networks and other chemometric techniques will allow present and future spectroscopists to extract useful diagnostic and chemical information from the almost overwhelming abundance of analytical data generated by the present and future generations of array detectors.

关键词： spectroscopic instrumentation plasma spectroscopy volume phase technology charge injection devices array detectors charge transfer devices

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Techniques in infra-red astronomy

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ELECTRONICS & COMMUNICATION ENGINEERING JOURNAL 1998年第2期10卷 83-88页

作者： Jameson, RF Univ Leicester Astron Grp Leicester LE1 7RH Leics England

Astronomy at the infra-red wavelengths is a comparatively recent branch of the subject, having really only started circa 1970. Since that time it has grown enormously in scope and sensitivity. This paper reviews the t... 详细信息

关键词： photodetectors single element detectors Auxiliary and recording instruments in astronomy Photoelectric devices array detectors astronomical techniques Photodetectors Measurement standards and calibration array electronics arrays Reviews and tutorial papers calibration reviews Other astronomical and space-research instrumentation Detection of radiation (bolometers, photoelectric cells, i.r. and submillimetre waves detection) infrared detectors Astronomical photographic and electronic imaging, and photometry infra-red astronomy ground based astronomy astronomical instruments resource letters infrared astronomy

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A realistic model for point-sources imaged on array detectors: The model and initial results

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Experimental Astronomy 1995年第1-2期6卷 163-210页

作者： Merline, W.J. Howell, Steve B. Planetary Science Institute Tucson 85705 AZ 620 N. 6th Ave United States

We have constructed a computer model for simulation of point-sources imaged on two-dimensional detectors. An attempt has been made to ensure that the model produces "data" that mimic real data taken with 2-D detectors. To be realistic, such simulations must include randomly generated noise of the appropriate type from all sources (e.g. source, background, and detector). The model is generic and accepts input values for parameters such as pixel size, read noise, source magnitude, and sky brightness. Point-source profiles are then generated with noise and detector characteristics added via our model. The synthetic data are output as simple integrations (onedimensional), as radial slices (two-dimensional), and as intensity-contour plots (three-dimensional). Each noise source can be turned on or off so that they can be studied separately as well as in combination to yield a realistic view of an image. This paper presents the basic properties of the model and some examples of how it can be used to simulate the effects of changing image position, image scale, signal strength, noise characteristics, and data reduction procedures. Use of the model has allowed us to confirm and quantify three points: 1) The use of traditionalsize apertures for photometry of faint point-sources adds substantial noise to the measurement which can significantly degrade the quality of the observation;2) The number of pixels used to estimate the background is important and must be considered when estimating errors;and 3) The "CCD equation" normally used by the astronomical community consistently overestimates the signal-to-noise obtainable by a measurement while a revised equation, discussed here, provides a better estimator. © 1995 Kluwer Academic Publishers.

关键词： array detectors CCDs data analysis instrumentation photometry software

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Recent progress in imaging polarimetry

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SOLAR PHYSICS 1996年第1-2期164卷 243-252页

作者： Keller, CU National Solar Observatory Tucson USA

Recent instrumental developments in imaging polarimetry allow array detectors to reach a polarimetric sensitivity of 1 x 10(-4) of the intensity. New instrumental effects appear at these levels of sensitivity and generate spurious polarization signals with amplitudes of up to 5 x 10(-4). Here I discuss these effects and present methods to avoid them. Polarized spectra with an rms noise of 6 x 10(-6) may then be obtained. Furthermore a method is brought to the reader's attention that allows polarization measurements at the 1 x 10(-4) level with regular array detectors, e.g, in the near-infrared.

关键词： polarimetry spectroscopy array detectors

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DESIGN AND PERFORMANCE OF A HADAMARD-TRANSFORM INFRARED SPECTROMETER WITH NO MOVING PARTS

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APPLIED SPECTROSCOPY 1995年第9期49卷 1338-1346页

作者： TILOTTA, DC ZHOU, Z Department of Chemistry P.O. Box 9024 University of North Dakota Grand Forks North Dakota 58202

The development of an improved Hadamard transform infrared (HT-IR) spectrometer with no moving optical parts is described. This spectrometer is based on a thermo-optic array for the stationary encoding of radiation (TOASTER) fabricated from Nichrome resistance wire. The TOASTER HT-IR instrument utilizes a reversed Czerny-Turner optical mount and relies on entrance focal plane modulation for operation. This design allows the dedispersion optics to be eliminated while still providing for a multiplex advantage. In addition, a conventional mechanical chopper is not needed in this instrument because the TOASTER is used as a natural modulator. The TOASTER HT-IR spectrometer can acquire an infrared spectrum in the range of 2.5 to 11 mu m (4000 to 910 cm(-1)). Its spectral resolution is 0.07 mu m (similar to 7 cm(-1) at 1000 cm(-1)), and, for fifteen spectral resolution elements, the observation window is 0.5 mu m (similar to 48 cm(-1) at 1000 cm(-1)). In addition to the design of the instrument, this communication also examines the thermo-optic switching properties of the Nichrome wire used in the prototype TOASTER. Although the maximum switching speed of the Nichrome wire is governed by its thermal decay time, we show that the TOASTER can be operated faster than this limit by employing a preheating step.

关键词： HADAMARD TRANSFORM SPECTROMETRY INFRARED SPETROMETRY array detectors MULTIPLEX SPECTROMETRY

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ORDER-SORTING FILTER TRANSMITTANCE MEASURED WITH AN array DETECTOR

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OPTICAL ENGINEERING 1993年第8期32卷 1827-1834页

作者： HEANEY, JB BRADLEY, SE BLY, VT EWIN, AJ LA, AT NASA GODDARD SPACE FLIGHT CTROPT RES BRANCHGREENBELTMD 20771 NASA GODDARD SPACE FLIGHT CTRDETECTORS SYST SECTGREENBELTMD 20771

The simultaneous measurement of the spectrally and spatially variant transmittance of a linear variable order-sorting filter in a manner that closely resembles its conditions of actual use is described. The transmittance of a prototype order-sorting filter was measured in the 400-to 880-nm wavelength region by illuminating it with the output beam of a spectrophotometer while the filter was attached to the front of a 30 x 32 pixel silicon array detector. The filter was designed to be used in the output beam of a grating spectrometer to prevent the dispersal of higher diffracted orders onto an array detector. Areas of the filter that were spatially matched to the corresponding detector pixel column had measured peak transmittances of about 90% that were uniform to within +/-1.5% along a given column. Transmittances for incident wavelengths shorter than the desired bandpass, corresponding to the order overlap region, were measured in the 3 x 10(-3) range. Line spread function measurements made with the array detector indicated no significant beam spreading caused by inserting the filter into the beam.

关键词： ORDER-SORTING FILTERS GRATING SPECTROMETERS array detectors SPATIAL UNIFORMITY LINE SPREAD FUNCTION

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INTENSITY CALIBRATION AND SENSITIVITY COMPARISONS FOR CCD RAMAN SPECTROMETERS

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APPLIED SPECTROSCOPY 1993年第12期47卷 1965-1974页

作者： FRYLING, M FRANK, CJ MCCREERY, RL OHIO STATE UNIV DEPT CHEM120 W 18TH AVECOLUMBUSOH 43210

A calibrated tungsten source combined with a fiber optic was used to correct Raman spectra for instrumental response. With the placement of the fiber output at the Raman sample position, the product of throughput, collection efficiency, quantum efficiency, and sampled area could be assessed. This product is related to a spectrometer figure of merit, which provides a quantitative comparison of spectrometer sensitivity and signal-to-noise ratio. Four spectrometer configurations were compared to illustrate the approach. An additional feature of the white light calibration is correction of relative Raman peak intensities. This issue is particularly important due to the substantial differences between CCD quantum efficiency curves and those of photomultipliers or intensified photodiode arrays.

关键词： RAMAN MULTICHANNEL CCD array detectors CALIBRATION

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TRADING WAVELENGTH FOR ABSORBENCY RESOLUTION - PREDICTING THE PERFORMANCE OF array DETECTION SYSTEMS

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APPLIED SPECTROSCOPY 1993年第5期47卷 619-624页

作者： BROWN, CW Department of Chemistry University of Rhode Island Kingston Rhode Island 02881

Mid-infrared spectra of liquid mixtures measured at 4 cm-1 resolution and near-infrared spectra of synthetic natural gas samples measured at 2 cm-1 resolution were convoluted to determine the effect of low resolution on multicomponent analyses of these samples. The resolution of the liquid samples could be degraded to almost 100 cm-1 before significant effects on the quantitative results were observed. The minor components in the natural gas samples were sensitive to degrading the resolution;however, the major components, methane and ethane, and the BTU values were unaffected until the resolution was degraded to over 100 nm (approximately 600 cm-1 at 1225 nm). The convoluted spectra were also displayed across a simulated array detector to determine the effect of the number of pixels on quantitative analysis. Excellent results were obtained on the convoluted spectra of both the liquid and gas mixtures with 32 elements. The liquid samples could be analyzed with as few as 8 pixels.

关键词： NEAR-INFRARED array detectors CONVOLUTION GAS-PHASE SPECTRA DIODE arrayS MULTICOMPONENT ANALYSIS PRINCIPAL COMPONENT REGRESSION QUANTITATIVE ANALYSIS COMPUTER APPLICATIONS INFRARED SPECTROSCOPIC TECHNIQUES

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