Use of a tungsten filament lamp as a calibration standard in the vacuum ultraviolet
Sapphire windowed argon filled tungsten ribbon filament lamp in vacuum UV for application in photomultiplier quantum efficiency calibration
Buckley, J. L.↗
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Recent developments and applications of the SEC vidicon for astronomy
The engineering development of the SEC vidicon as an astronomical sensor has continued in parallel with its operational use. One scientific application was the six hour exposure of the quasar PHL-957 at the Coude spectrograph of the 200-inch Hale telescope. The developmental effort includes both the enhancement of the basic attributes that make the SEC an appropriate sensor, namely, high quantum efficiency, low threshold, and long integration; as well as work to broaden its scientific usefulness, such as the development of a MgF2 photocathode window for vacuum ultraviolet sensitivity, and a permanent magnet focus design for thermal compatibility with proposed large space telescopes. Additional details on the characteristics of the SEC tube are discussed, as well as plans to make a larger and higher resolution version.
Zucchino, P.↗
High-sensitivity receiver for infrared laser communications.
Description of a high-sensitivity wide-bandwidth 10.6-micron heterodyne receiver for space and ground operational use. The receiver includes a cooled HgCdTe infrared mixer diode, a conical scanner for spatial tracking, an acquisition channel for spatial search and station alignment, and an automatic frequency-control channel to maintain a fixed laser frequency offset. The infrared mixer is designed to provide nearly quantum-noise-limited operation over an extended range of mixer temperature, bias voltage, and intermediate frequency. The resultant experimental receiver has a measured noise equivalent power of less than 10 to the minus 19th W/Hz over the 15- to 40-MHz i.f. band for mixer temperatures from 85 to 115 K, and less than 2 x 10 to the minus 19th W/Hz up to 140 K. Mixer 3-dB cutoff frequencies as high as 420 MHz were measured at a mixer temperature of 125 K. An analysis and engineering equations are given for receiver noise components, noise equivalent power, available mixer conversion gain, mixer transducer gain, and quantum-noise factor in terms of such factors as mixer parameters, quantum efficiency, mixer temperature, dynamic conductance, bias voltage, local oscillator power, and i.f. amplifier characteristics.
Peyton, B. J.↗
The silicon vidicon: Integration, storage and slow scan capability - Experimental observation of a secondary mode of operation.
Description of the performance of the silicon diode array vidicon - an imaging sensor which possesses wide spectral response, high quantum efficiency, and linear response. These characteristics, in addition to its inherent ruggedness, simplicity, and long-term stability and operating life make this device potentially of great usefulness for ground-base and spaceborne planetary and stellar imaging applications. However, integration and charged storage for periods greater than approximately five seconds are not possible at room temperature because of diode saturation from dark current buildup. Since dark current can be reduced by cooling, measurements were made in the range from -65 to 25 C. Results are presented on the extension of integration, storage, and slow scan capabilities achievable by cooling. Integration times in excess of 20 minutes were achieved at the lowest temperatures. The measured results are compared with results obtained with other types of sensors and the advantages of the silicon diode array vidicon for imaging applications are discussed.
Ando, K. J.↗
Optimum detection of an optical image on a photoelectric surface
The detection of an optical image in the presence of uniform background light is based on a likelihood ratio formed of the numbers of photoelectrons emitted from small elements of a photoelectric surface onto which the image is focused. When diffraction is negligible and the surface has unit quantum efficiency, this detector is equipollent with the optimum detector of the image forming light. Its performance is compared with that of the threshold detector and that of a detector basing its decisions on the total number of photoelectrons from a finite area of the image. The illuminance of the image is postulated to have a Gaussian spatial distribution. All three detectors exhibit nearly the same reliability.
Helstrom, C. W.↗
Photodiodes for ten micrometer laser communication systems
The performance is discussed of 10-micron mercury-cadmiumtelluride and lead-tin-telluride photodiodes in laser heterodyne communication systems. The dependence of detector quantum efficiency, resistance, frequency response, and signal-to-noise ratio on temperature, bias, and local oscillator power are examined. Included in the discussion is an analysis of the feasibility of high temperature operation, and ability of the detector to dissipate power to a heat sink is explored. Some aspects of direct detection response are considered and figures showing flux levels from a blackbody presented.
Cohen, S. C.↗
Photolysis of O3 at 3130A
The photolysis of O3 at 3130 A and 25 C has been studied in the presence of a large excess of N2O to react with any O(1D) atoms produced. From the N2 produced, the quantum efficiency for O(1D) production was found to be 0.50 + or - 0.03.
Simonaitis, R.↗
Performance characteristics of proximity focused ultraviolet image converters
Performance characteristics of Bendix type BX 8025-4522 proximity focused image tubes for ultraviolet to visible light conversion are presented. Quantum efficiency, resolution, background, geometric distortion, and environmental test results are discussed. The converters use magnesium fluoride input windows with Cs - Te photocathodes, and P-11 phosphors on fiber optic output windows.
Williams, J. T.↗
Ultraviolet proximity focussed converters for use in a satellite SEC-TV system.
Performance characteristics of Bendix type BX08025-4522 proximity-focussed vacuum-ultraviolet to visible-light image converters are presented. The converters are to be used with SEC vidicons as detectors for an echelle spectrograph on the International Ultraviolet Explorer astronomical satellite. Magnesium fluoride input windows with Cs-Te photocathodes are used in the converters, with P-11 phosphors on the fiber optic output windows. Quantum efficiencies, modulation transfer function, background, geometric distortion, and environmental test results are presented for the wavelength region from 1150 to 3500 A.-
Feibelman, W. A.↗
Development and evaluation of television tubes for space astronomy
An improved vidicon image sensor for space astronomy applications is developed that features reliably sealed ultraviolet transmitting windows and achieves acceptable photocathode quantum efficiency on these MgF2 windows. New preamplifier designs improve the dynamic range by reduction of the readout noise.
Spitzer, L.↗
Performance characteristics of proximity focused ultraviolet image converters
Performance characteristics of Bendix type BX 8025-4522 proximity focused image tubes for UV to visible light conversion are presented. Quantum efficiency, resolution, background, geometric distortion, and environmental test results are discussed. The converters use magnesium fluoride input windows with Cs-Te photocathodes and P-11 phosphors on fiber optic output windows.
Williams, J. T.↗
Single photon detection and sub-nanosecond timing resolution with RCA C31034 photomultiplier
The very high quantum efficiencies and low dark count rates achieved with selected RCA C31034 photomultipliers make them attractive candidates for single photoelectron fast timing experiments. Single photoelectron plateau counting and a timing resolution of 0.60 nsec (FWHM) were obtained using fast amplifiers, constant fraction timing discriminators, and a pulsed light emitting diode. A redesign of the C31034 incorporating features of the very fast C31024 is suggested to yield even better timing resolution.
Reisse, R.↗
Negative affinity X-ray photocathodes
A new X-ray image intensifier is described. The device should eventually have a quantum efficiency which is an order of magnitude greater than that of presently available high spatial resolution X-ray detectors, such as microchannel plates. The new intesifier is based upon a GaAs crystal photocathode which is activated to achieve negative electron affinity. Details concerning the detector concept are discussed together with the theoretical relations involved, X-ray data, and optical data.
Vanspeybroeck, L.↗
Television photometry - The Mariner 9 experience
Television photometry is compared to conventional techniques. Reduced data from Mariner 9 cameras should, under optimum conditions, have been accurate to a few percent. However, a combination of unstable camera properties and various unfortunate circumstances produced serious nonlinearities and other systematic errors. The means of estimating these errors are described in detail; they lean heavily on the fortuitous presence of a few specks of dust on the faceplate of one vidicon. Crude corrections will probably improve the photometric quality for the two most-used filter positions of the A camera. It would be very difficult to improve the photometry further. In view of their low photometric accuracy and detective quantum efficiency vidicons do not seem likely to replace conventional photography, except for special applications.
Young, A. T.↗
X-ray sensitive oblique imaging device
Instrument employs light reflecting surface (evaporated aluminum coating or minor substrate) behind phosphor screen to improve effective quantum efficiency in dual process: fraction of incoming X-rays are converted to photoelectrons at photocathode; and X-rays that pass through photocathode and thin X-ray transparent membrane enter phosphor screen.
Hallam, K. L.↗
Applied research on 2-6 compound materials for heterojunction solar cells
Several II-VI heterojunctions show promise for photovoltaic conversion of solar energy. The three of greatest interest are p-CdTe/n-CdS, p-CdTe/n-ZnSe, and p-ZnTe/n-CdSe. Several p-CdTe/n-CdS heterojunction cells have been prepared by close spaced transport deposition of p-CdTe on single crystal n-CdS, and by two source vacuum evaporation of n-CdS on single crystal p-CdTe. Both types of cells, in an experimental stage, are quite comparable, exhibiting values of quantum efficiency between 0.5 and 0.9, open circuit voltages between 0.50 and 0.66 V, fill factors between 0.4 and 0.6, and solar efficiencies up to 4 percent. Cells of p-ZnTe/n-CdSe have also been made by close spaced vapor transport deposition of n-CdSe on single crystal p-ZnTe.
Bube, R. H.↗
Semiconductor electrolyte photovoltaic energy converter
Feasibility and practicality of a solar cell consisting of a semiconductor surface in contact with an electrolyte are evaluated. Basic components and processes are detailed for photovoltaic energy conversion at the surface of an n-type semiconductor in contact with an electrolyte which is oxidizing to conduction band electrons. Characteristics of single crystal CdS, GaAs, CdSe, CdTe and thin film CdS in contact with aqueous and methanol based electrolytes are studied and open circuit voltages are measured from Mott-Schottky plots and open circuit photo voltages. Quantum efficiencies for short circuit photo currents of a CdS crystal and a 20 micrometer film are shown together with electrical and photovoltaic properties. Highest photon irradiances are observed with the GaAs cell.
Anderson, W. W.↗
Ion implanted photodiode detectors in epitaxial /Ga/x/In/1-x//As
Ion implanted p-n junction photodiodes in epitaxially grown (Ga(x)In(1-x))As material are reported on here. Photoresponse in these diodes was investigated for approximately the entire composition range of x between zero and one. High values for quantum efficiency were obtained for the devices with a high value of x.
Ajmera, P. K.↗