Image Orthicon Research Articles

Television cinemaphotography of auroras and preliminary measurements of auroral velocities

During October 1963 a series of tests were performed at Fort Churchill, Manitoba, on the usefulness of an image orthicon closed-circuit television system for indirect auroral photography. The system used was similar to one described in a paper by Hicks [1963]. It was equipped with an f/0.75 lens providing an effective field of view of 16°. Recording was accomplished by photographing the television monitor with a 16-mm cinema camera.

Measurement of noise in image orthicon

Measurement of noise in image orthicon

Cinematography of Spatial and Temporal Variations in Auroral Forms with an Image Orthicon TV System.

A new technique for cinematographic recording at 24 frames per see of variations in auroral forms is discussed. The equipment is a very sensitive image orthicon television system from whose monitor the image is photographed with a 16-mm movie camera. The technique permits changes in auroral forms to be studied which occur in as little as 1/24 sec.

Facts and Myths Concerning Image Tubes.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Facts and Myths Concerning Image Tubes. Baum, William A. Abstract For the blue region of the spectrum commonly used in astronomical spectroscopy, the gain of image tubes over the best unaided photographic emulsions cannot exceed a factor of about 20. The larger figures often quoted are fundamentally impossible. Electronographic tubes, cascaded converters, and mica-window converters offer the best hopes for actually achieving gains of 10 or more. Present performance is not consistently as good as this but is progressively improving. Imaging photomultipliers are running somewhat behind, and scanning tubes (such as the image orthicon) are the poorest of the candidates. When various image tubes are being compared with one another and with unaided photography, their performance must be judged in terms of their relative "information rates." Separate figures on resolution and speed-gain can be misleading. Publication: The Astronomical Journal Pub Date: 1964 DOI: 10.1086/109384 Bibcode: 1964AJ.....69Q.532B full text sources ADS |

イメージオルシコンにおける走査電子ビームの軌道

イメージオルシコンの第1ダイノード孔から出て, 再び帰還する電子ビームの振舞を解析し, ターゲット近傍における走査パターンの回転と, ダイノード走査との相関, ならびに電子銃の曲がりと補正磁界との関係を導出した.その結果を5820形イメージオルシコンに適用すると, ダイノード走査の大きさより逆算してターゲット近傍での走査パターンの回転は, 約3°と推定される.また電子銃の1°の曲がりは, 約0.5ガウスの補正磁界に対応している.

The digital analysis of electron-optical systems

Very accurate methods which are particularly suitable for use on digital computers are described for the analysis of electron-optical systems having cylindrical symmetry. The electric fields are determined using a highly convergent iterative method, and the magnetic fields are determined from analytic expressions fitted to physical measurements of the fields along the axes of the systems. The equations of electron motion are integrated using predictor-corrector methods with automatic control of the integration interval. The methods are sufficiently accurate to permit the detailed analysis of systems in which high-order imaging properties are important. Results obtained for an image orthicon camera tube and an image converter tube are also described.

イメージオルシコンの真空度測定法

イメージオルシコンの真空度測定法

PROGRESS IN STEREOFLUOROSCOPY "TRANSMISSION": T-V ANAGLYPH DISPLAY AND COLOR CINERECORDING.

In the face of the remarkable apathy of most radiologists the world over to the application of stereoscopy in roentgen diagnosis, we have remained convinced of the ultimate value to be derived from the clinical use of a refined system for stereoscopic fluoroscopy. A few other workers share our convictions, notably Lindblom (2), Webster (3), Potsaid (4), and Sones (5). Our Radiology-Physiology-Medical Physics Research Group demonstrated in 1954 the practicability of Vidicon closed-circuit television display from the first commercially available 5-in. Philips image intensifiers (6). However, the development of a stereoscopic televised fluoroscopy system required rapid handling of alternating images on the output phosphor from the two x-ray tube targets; we, therefore, selected the image Orthicon for this application since its photo-cathode can be pulsed and it is free of the objection-able lag of the Vidicon. In 1962, with Henny (7), we reported the development of a functioning experimental arrangement for ...

Resolution of electrostatic storage targets

In the class of electrostatic storage devices, which includes image orthicons, vidicons and certain signal recorders, a reading electron beam senses the potential distribution rather than the written charge distribution on a target. The transformation of a charge pattern into a potential pattern on a dielectric surface can be considered an imaging process. In this paper the theoretical aperture response and equivalent pass band of a general electrostatic storage target are derived. Target resolution is shown to depend upon the thicknesses of the dielectric layers. Specific applications of the analysis are also presented. The paper concludes with a discussion of experimental results.

Resolution Capability of the Image-Orthicon Camera Tube under Nonstandard Scan Conditions

The resolution properties of the image orthicon have been studied experimentally for nonstandard scanning rates applicable in scientific observation. Resolution may be improved by (1) raising the photocathode voltage, (2) separating the exposure and scanning operations in time so as to minimize the effect of leakage of scan fields into image section, (3) cooling the target and (4) scanning slowly without reduction of bandwidth. When operated as suggested with highlights near the “knee,” the 3-in. image orthicon has an amplitude response of 50% at 900 TV-lines and a limiting resolution of about 1500 TV-lines. With increased illumination a limiting resolution of 3000 TV-lines (60 line-pairs/mm) is attained. Maximum resolution is set by capacitive coupling between elements at the target. Response to stellar or point source images is discussed. Measurement techniques and the sine-wave response of test lenses are given.

The Comparative Performance of Electron Tube Photodetectors in Terrestrial and Space Navigation Systems

Celestial tracking systems employed in the navigation of military vehicles in the atmosphere of the earth have the capability of tracking a large number of stars in the daytime. In daytime tracking, the quantum efficiency of the detector, as well as additional sensitivity gain through electronic charge storage, is of primary importance. Theoretical formulas for the signal-to-noise ratios of four detectors are presented: the photoelectric photomultiplier, image dissector, vidicon and the image orthicon. The photomultiplier and image dissector require the use of very slow scanning velocities, narrow detection bandwidths, and the resultant time required for star acquisition is in the order of minutes. The image orthicon, due to target saturation, is restricted to the observation of only bright stars. The vidicon, with sensitivity gain through electronic charge storage, is used with rapid scanning velocities, and star acquisition is accomplished in less than one second of time. In interplanetary or nighttime navigation, with a low level of background radiation, the salient detector characteristics are sensitivity, gain through either storage or photomultiplication, and dark current. The image dissector rates first among the detectors considered, followed by the photomultiplier, image orthicon and the vidicon. Field test data are presented in this work in substantiation of the analysis of the several detector types.

Light-curve of RV Ari obtained by means of an image Orthicon tube.

Light-curve of RV Ari obtained by means of an image Orthicon tube.

Information Capacity of Radiation Detectors and of Light

Data are presented on the information capacity and on the information efficiency of a beam of light and of several kinds of detectors including heat detectors, a multiplier phototube, an image orthicon, four photographic films, and human vision. The information efficiency is the information capacity divided by the number of photons that are needed to achieve the capacity, and is measured in bits per photon. The photographic films are discussed in separate sections from two points of view: that of maximizing the information capacity in bits/cm2, and that of maximizing the information efficiency. The other detectors and the beam of light are discussed only from the point of view of maximizing the information efficiency, because there is no upper bound to the information capacity that is related to practical use. The paper is primarily a review of the results of four previously published papers, but some new material is included: The results in Tables I and II on the information capacity of a beam of light are more extensive and more accurate than those previously published, and an explicit proof is given for the fact that it is not necessary to employ a radiation signal having spatial structure to obtain the greatest information efficiency with an image-transducing detector; a time varying radiation signal incident at a single point of the responsive surface is sufficient to achieve the maximum possible information efficiency.

Target scan parameters as they affect the performance of camera tubes

An analysis of target scan parameters as they affect the performance of electron-bombardment-induced-conductivity (EBIC) and photoconductive (PC) camera tubes is presented. The signal currents and the associated surface potentials are determined analytically as a function of the excited target resistance, beam current, and the secondary emission characteristics of the target surface. Experimental techniques for measuring the pertinent parameters by application of this analysis are described, and characteristic data for PC and EBIC-type camera tubes presented. The effect of these parameters on the signal-to-noise ratios and ultimate resolving capabilities of these types of camera tubes are compared with similar data on image orthicon type tubes.

Isocon Scan–A Low-Noise, Wide-Dynamic-Range Camera Tube Scanning Technique

In Isocon scan of an image-orthicon type camera tube, the video signal is derived from those electrons in the scanning beam which are scattered at the storage target. Using suitable electron optics, these scattered electrons may be collected and amplified in the electron multiplier along with only a small fraction of unmodulated return beam electrons. In contrast, the output signal obtained with orthicon scan contains a large unmodulated current. Isocon scan introduces much less noise than orthicon scan and extends the useful range to lower illumination levels. The dynamic range of light levels in a single scene that may be handled by an Image Isocon may be an order of magnitude greater than with conventional image orthicons. A dual-mode camera tube capable of operation either with orthicon scan or with Isocon scan is described. A signal-to-noise analysis is presented for both types of scan. The results of the measured performance compare favorably with that predicted by the analysis.

Image Orthicon Astronomy at the Dearborn Observatory

For a given signal-to-noise ratio, the image orthicon can record stars to a theoretical magnitude limit set primarily by skylight. A “skylight suppression” technique under development appears capable of increasing available integration time and hence the limiting magnitude. Short exposure pictures of the moon under high magnification show about ½-sec resolution with good seeing, and an 18.5-in. (47-cm) telescope; under certain conditions the image orthicon can be used to provide better resolution than possible with emulsions, owing to the shorter exposures which are feasible even with high-magnification projection optics. Among other electronic devices which have been used are the intensifier orthicon, the image isocon, and, most promising, the field mesh orthicon. Brief descriptions of these devices are given as a matter of general interest, although they are not in use at Dearborn Observatory. A list of some Dearborn Observatory projects in electronic astronomy is presented to suggest the wide range of application of this new technique.

Operational Improvements in Image Orthicon Camera Equipment

A modern broadcast TV Camera adaptable for use with either 3-inch or 4?-inch image orthicon tubes is described. Circuit and mechanical innovations are discussed which result in improved stability and reliability. Simplified operation and maintenance of the camera are emphasized.

Closed Circuit Television Techniques

Closed circuit television operations have been able to make use of the vidicon camera to advantage and its use is suggested for particular broadcast applications. Where high illumination and flat lighting is available, the vidicon is preferable to the image orthicon as a pickup device because of its greater economy, stability, ruggedness, simplicity of circuitry and small size, and excellent picture quality.

Recent Experiments with Image Tubes at Kitt Peak National Observatory.

The image orthicon television-camera tube has been tested as the light receiver for a fast nebular spectrograph on the 36-inch telescope. Observations of astronomical objects, with exposure times of up to 90 min, demonstrate the ability of the system to record faint emission features which could not be reached by photographic methods on this telescope. However, various effects that are peculiar to the image orthicon such as beam bending and low latitude, seriously limit the quantitative aspects of the spectra. More encouraging results have been obtained with a high-gain imaging photomultiplier (English Electric Valve P829) which permits the certain recording of individual photoelectrons. A pulse counting field photometer utilizing this type of tube is being developed. At the 60-inch solar telescope the imaging photomultiplier has been used for highdispersion work on the planets and bright stars.

イメージオルシコンの製作

現在テレビジョン放送に最も多く使用されている撮像管イメージオルシコンの製作工程について概説する.