Image Orthicon Research Articles

Pioneers of Television — Philo Taylor Farnsworth

This is the third in the series of “Pioneers of Television,” written for the SMPTE Journal. Philo T. Farnsworth was one of the most prolific inventors in television history, with over 75 important inventions in his name. Born in 1906 in Utah, he conceived an all-electric system of television while only 15 years of age. He typified the school of inventors that not only conceived the ideas but built and implemented them. By the time he was 21 he had secured financing and was operating a laboratory in San Francisco, from which came a host of important inventions. Farnsworth was the first inventor in the world to build and operate an all-electric television system, in July 1929. This included an electric camera tube, the image dissector; a vacuum-tube scanning, blanking, and sync generator; and a magnetically focused cathode ray tube. His image dissector camera tube was the first to pick up “live” images in broad daylight. He was the inventor of the method for generating anode high voltage from the scanning currents. His research in camera tubes led him to patent the first camera tube to use a low-velocity electron beam that scanned a target at cathode potential. This led to the Orthicon and Image Orthicon camera tubes that made postwar television possible. Farnsworth's imagination knew no limits, and without his inventions no modern-day television system could operate. Yet in spite of these considerable achievements, he is relatively unknown and has been overshadowed by other pioneers in television history.

Low amplitude measurement by direct lock-in ESPI, a proposal

A method for mapping of low vibrational amplitude and phase distributions is proposed. The method is based on the use of an image orthicon TV-camera as a two-dimensional lock-in amplifier. The potentials of the technique are discussed, and compared to similar techniques.

Background rejection in schlieren visualization

It was recently suggested that an image orthicon could be used as a two-dimensional array of lock-in amplifiers. This technique enables rejection of extraneous optical signals from images of periodic phenomena, and the suitability of the method to improve schlieren images of ultrasonic beams is verified by experimental results.

Moire Pattern in Color Television

The overlapping of two periodic line patterns of the same general magnitude can produce larger scale visible patterns called moire fringes. In shadow mask picture tubes a design objective is to prevent such unsought patterns from being produced by the interaction of the scan line pattern with the pattern of mask holes or phosphor dots. This goal is the subject of this paper, although a broader examination of moire in color television would include other spurious patterns in the reproduced picture. These could be caused by interference between two or more patterns such as the original subject, the target grid of the image orthicon, scan line pattern, mask-screen pattern, and carrier color signal periodicity.

Use of an image orthicon as an array of lock-in amplifiers

If the accelerating voltage is modulated, an image orthicon TV camera can be operated as a synchronous, bipolar image detector. Experimental verification of this mode of operation is presented.

The Echo 4 Electron Beam Experiment: Television observation of artificial auroral streaks indicating strong beam interactions in the high‐latitude magnetosphere

Ten artificial auroral streaks produced by the Echo 4 rocket‐borne electron accelerator were recorded with an image orthicon television system. The streaks were viewed normal to their direction along the magnetic field, and the threshold accelerator power necessary for optical imaging was found to be near 1 kW. The observed streaks were all produced by beams injected downward from the rocket directly into the atmosphere. Upward‐injected beams of up to 2‐kW power did not produce optically observable echo auroras after the hemisphere‐to‐hemisphere round trip, although echoes were observed by particle counters on the rocket. The failure to observe the echo auroras optically may be the result of strong pitch angle scattering. The positions, orientations, altitudes, and vertical extents of the observed streaks are in satisfactory agreement with model calculations. Some of the streaks had diameters of ∼5 times the electron gyroradius. This is the expected collisional spreading for a beam that, above the atmosphere, is confined to a single gyrodiameter. Other streaks, injected from rocket apogee (215 km), exhibited substantial fluctuations in width that are interpreted as evidence for strong beam interactions with the ambient ionosphere.

SeBiI alloy: A high sensitivity visible—near IR photoconductor

The development and characterization of an amorphous SeBiI alloy system whose electrophotographic sensitivity is substantially greater than either selenium or arsenic triselenide at all visible wavelengths and whose sensitivity extends beyond 800 nm are described. Amorphous films were prepared by flash evaporation in vacuum of thermally blended alloys. A composition matrix of bismuth and iodine in selenium was surveyed to identify the optimum alloy. Alloys containing approximately equal amounts of bismuth and iodine were found to be more structurally stable and have more desirable electrophotographic properties than either alloys varying from these compositions or the iodine-free selenium-bismuth binary system. The optimum alloy contained about 3 at% bismuth, 3 at% iodine and 94 at% selenium. The alloy system would appear to have utility wherever panchromaticity or near infrared sensitivity is required and thin photogeneration layers can be tolerated. Potential applications lie in devices with multilayer configurations, in image orthicons and laser coupled devices.

An X-ray television system for rapid recording and processing of diffraction patterns

An X-ray television camera using a phosphor screen coupled to an image orthicon tube was prepared to detect and record diffraction patterns rapidly. It is about 750 times more sensitive than photographic film, producing a video signal of S/N = 10 for incident 4 × 104 Cu Kα quanta sec−1 mm−2, and has a dynamic range of 1:30 and a spatial resolution of 6.4 Lp mm−1. The detector system was tested by recording rotation patterns from a single-crystal of diformylhydrazine, where it was demonstrated that one can measure reflection intensities with an accuracy better than 10%. To process the TV picture by computer, an image readout device using a storage tube was built. The high sensitivity and the large detection window (42 mm in diameter) of the camera and the fast speed (40 μs for each 80 × 80 μm resolution element) of the readout device make the incorporated system most appropriate for rapid measurement of simultaneous reflexions from macromolecular crystals. The camera can also record small-angle diffraction patterns from muscle in an exposure time of a few seconds.

TheL= 6.6 Oosik Barium Plasma Injection Experiment and magnetic storm of March 7, 1972

The high-altitude detonation of a high-explosive shaped charge vaporizes a hollow conical liner of barium metal and produces a fast field-aligned jet of plasma with approximately 1 mol of ions having initial velocities distributed from 8 to 20 km/s. Such a barium plasma injection experiment was performed at 540-km altitude over Alaska (L = 6.6) in dusk of March 7, 1972 (universal time), in an attempt to trace out and observe the dynamics of an auroral field line in the magnetosphere. With image orthicon TV systems and image intensified cameras the resulting streak rising into the magnetosphere was observed for 30 min and out to 3-RE altitude. A 1.5-m-aperture photometer detected the barium streak at R (release) + 35 min at nominal look angles where the ions would be near altitudes of 5 and 2 RE from the magnetic equator. The injection occurred during a quiescent phase of a magnetic storm initiated by an ssc 10 hours prior to the experiment. Quiet auroral arcs existed over Alaska at locations more than 200 km south of the injection point. The barium flux tube drifted first eastward and then southward owing to an electric field E, with E × B/B² velocities of several hundred meters per second, while also splitting into at least seven separate flux tubes distributed along 200 km parallel to L. At R + 16 min an intense auroral activation and magnetic substorm (the Oosik substorm) began in the Alaskan sector. Subsequent poleward expansion of the aurora and formation of a classic spiral resulted in the intersection and crossing of the barium flux tubes by an auroral arc. Very rapid, almost turbulent, motions of the barium flux observed during the intersection interval resulted from local transient E fields of 200 mV/m directed inward toward the auroral arc. Observations of the distortion of the barium flux tubes on opposite sides of the aurora as compared with a field model including the superdisturbed external coefficients of Mead and Fairfield (1973) offer evidence for an upward Birkeland current sheet at the poleward edge of the auroral spiral of 8 × 10−2 A/m. The Oosik substorm was spatially limited to the dusk sector; it occurred during the decaying phase of a larger substorm observed in the midnight to dawn sector. The substorm and aurora had several unusual features. Examination of the question as to whether the plasma injection may have triggered the substorm unveiled no compelling evidence that it did; however, the unusual features of the substorm leave open that possibility.

Spectroscopy of pico-second light pulses with a television camera system

A television camera system using a high-sensitivity image orthicon is constructed for spectroscopic measurements in the pico-second region. It is possible to fix the spectrum of a relatively weak pico-second light pulse as a static spectrum on the screen of an oscilloscope. Time-resolved luminescence spectra from a heavily-excited GaAs crystal in the pico-second region are demonstrated as examples of measurements using this system.

The television camera in dynamic vidioangiography.

Abstract Three characteristics of conventional television cameras—image integration and storage, interlaced scanning, and image retention—make these cameras unsuitable for dynamic angiography. Use of noninterlaced scanning and synchronized 60/sec. pulsed operation of the x-ray source avoids degradation of temporal resolution caused by image integration and provides discrete video images at 60/sec. if cameras with minimal image retention are used. Image orthicon, lead monoxide vidicon, and silicon diode integrated target epicon camera tubes have less than 10% image retention after single scans and are suitable for angiography. Stop-action films of television displays confirm the poor temporal resolution of conventional cameras.

High-Resolution Video Display of X-Ray Topographs with the Divergent Laue Method

An X-ray imaging device utilizing a high sensitivity image orthicon tube has been incorporated in the divergent Laue method of diffraction topography using a point source. An X-ray optical magnification of diffraction images has made it possible to obtain a spatial resolution better than that of the imaging device. Preliminary experiments have demonstrated that individual dislocations in silicon crystals can be displayed with a resolution of better than 25 µm.

Nanosecond High Resolution Framing Camera

A framing camera employing proximity focused image intensifiers with an effective frame rate of 108 frames/sec and a spatial resolution of greater than 10 line pairs/mm on the 25 mm diam photocathode has been constructed and tested. The camera consists of six proximity focused image intensifiers coupled in a hexagonal array. This array may be viewed by either a standard film camera or an image orthicon television camera for remote monitoring. Interframe duration is adjustable from overlapping to several times the frame duration. Frame duration is adjusted by changing the pulse width from the main pulse generator. The shuttering circuit demonstrates zero interframe jitter and accurately known interframe and frame durations. Tests indicate there is no physical reason this technique cannot be extended to equivalent frame rates of greater than 109 frames/sec using low resistance photocathodes.

Image Orthicon Spectrograph with Computer Control

A spectrograph using an image orthicon tube for low light level spectroscopy has been constructed. It has been tested for rapid raman spectroscopy and, with computer control, for transient absorption spectra of ions excited to metastable states. The advantages and disadvantages of the instrument are discussed.

Mass Influx Obtained from Low-Light-Level Television Observations of Faint Meteors

Since the advent of low-light-level television (LLLTV) systems, it has been recognized that such devices offer the ability to observe meteors as faint as 10th magnitude which allows the extension of optical meteor data to masses as small as 10-4 gram. The Space Sciences Laboratory at Marshall Space Flight Center has been actively engaged in such observations using image orthicons and intensified SEC vidicons.The results of these observations are presented along with an interpretation in terms of mass-flux. This interpretation includes the development of a relationship between peak luminosity of a meteor and mass, velocity, and zenith angle that was derived from single body meteor theory and compares favorably with results obtained from the Artificial Meteor Program. Also included in the mass-flux interpretation is an analysis of the observation response of a LLLTV system to fixed and moving point sources.

Minimizing the image retention on image orthicon targets: J Prchlik et al, Tesla Electronics, 3 (3), 1970, 83–87

Minimizing the image retention on image orthicon targets: J Prchlik et al, Tesla Electronics, 3 (3), 1970, 83–87

Spectroscopy of Perseid Meteors with an Image Orthicon

An image orthicon technique for recording meteors, developed some years ago by Hemenway at the Dudley Observatory, has recently been used at the Springhill Meteor Observatory, Ontario, for the recording of meteor spectra and combined with three other observational techniques—meteor radars, spectrographs, and a team of visual observers. Fifteen meteors, observed with the image orthicon during the August campaign in 1969, are here discussed out of a total of more than forty. Apparent visual magnitudes range from −1 to +3 and all 14 Perseid spectra in this group exhibit the oxygen green line at 5577 Å as well as other atomic lines normally found in the spectra of members of this shower. At the beginning of their trails all meteors show either a strong continuum, or evidence of band structure where the 1st and 2nd positive systems of N2 have been identified with reasonable certainty, while the first negative systems of N2+ and O2+, and the visible system of OH, are possible contributors.Measures of the 5577 Å line indicate a height spread from 120 to 95 km with a maximum near 106 km. After initial formation the intensity of this line increases for 0.2 to 0.5 s, after which it decays over periods up to 2 s. The decay constant for the 1S metastable state of neutral atomic oxygen is 0.76 s−1.The two chief advantages of the image orthicon technique are: its ability to record meteor spectra down to fainter thresholds of luminosity than in the case of conventional spectrography, and the time-resolution given by a recording of 15 complete frames per second.

Meteor Spectroscopy Using an Image Orthicon

A brief description of a technique for recording faint meteor spectra with a high sensitivity image orthicon tube is given. The use of a video tape recorder technique makes it possible to study the development and decay of time dependent features such as the auroral green line 5577 Å in meteor spectra.

APPLICATION OF AN IMAGE ORTHICON CAMERA TUBE TO X-RAY DIFFRACTION TOPOGRAPHY UTILIZING THE DOUBLE-CRYSTAL ARRANGEMENT

A video imaging system utilizing a high sensitive image orthicon camera tube has been set up and applied to x-ray diffraction topography using the double-crystal arrangement of parallel setting. The system gives a video signal of S/N 20 dB for incident 3 × 104 x-ray photons sec−1 mm−2. The resolution of the system is 300 μ for 70% of the modulation transfer function, limited presently by the resolution of the x-ray phosphor. As an example, long-range elastic strains in an Sb-doped silicon crystal have been studied.

Shock Tube Studies Using Image Orthicon Spectroscopy

An image orthicon detection and recording system has been adapted for making spectroscopic measurements in shock tube emission studies. The system provides greater sensitivity than film and permits electronic control of both the timing and duration of the exposure. The linear response with light intensity and immediate recording of output on an oscilloscope trace makes the system a convenient diagnostic tool. A description of the system as well as quantitative spectroscopic data obtained with it is presented.