Low Light Level Television Camera Research Articles

Dynamic neutron radiography instrumentation and applications in Central Europe

Characteristic features of simultaneous dynamic neutron and gamma radiography installations built in the last ten years at the Budapest/Hungary and at the Seibersdorf/Austria research reactors are surveyed. For image detection scintillation detectors and a low-light level television camera with video output are used, thereby providing the possibility for visualizing medium speed movements inside the investigated object. The radiography stations have been used for inspecting industrial products, with the aim of research and development.

Advances in strain measurement using electron-backscatter diffraction in the Scanning Electron Microscope

The technique of electron back scatter diffraction, EBSD, is well established for measurement of crystal orientation in bulk polycrystalline samples. Analytical procedures for determining crystal phase from them have also been established. In addition several papers have been published describing the application of the method for strain measurement. In these latter studies the EBSPs were recorded on photographic film and all measurements made after digitising the patterns and transferring the data to a SEMPER image processing package. Strain measurement was based on determination of the diffuseness of the diffraction pattern. In the present studies analysis was carried out on digitised television images of the diffraction patterns imaged live on a phosphor screen.EBSPs were obtained in a JEOL 6400 SEM fitted with a tungsten filament. The patterns were imaged on a P20/P40 phosphor directly coupled through a coherent fibre optic bundle to a SIT low light level television camera with 700 line resolution.

Simple, inexpensive optical beacon for use on small satellites

A Vivitar model 283 photography flash unit was modified and tested for use as an aid for acquiring a target in low-Earth orbit. External circuitry was added to control the flash rate and pulse duration; the relative visibility of the flash was then tested with respect to these parameters, using two types of low-light level television camera systems over a range of effective distances. A rate of 40 flashes/min and a pulse duration of 1.8 ms were found to be optimal within the power capabilities of the existing inverter circuit. Removing the color correcting lens in front of the flash tube was also found to improve the efficiency of the unit in this application.

Fragmentation of a meteor in near-Earth space

Fragments of a Perseid meteor, which broke up well above the Earth's atmosphere, probably in collision with a dust particle in near Earth space, have been observed with a two-station low-light level television camera system. Three Perseid meteoroids, with apparent magnitudes between 2.0 and 3.5, arrived on near parallel trajectories within 1.3 s of each other on the morning of 12 August 1977 (03.05.21–03.05.23 UT). The probability of these meteoroids arriving by chance so close together in time and direction is very small (∼3 × 10−11). Assuming the three meteoroids were fragments of a larger body, we show here that the parent meteor must have broken up at least 1,700 km above the Earth's surface, well above the altitude at which meteoroids normally start to burn up in the Earth's upper atmosphere (100–150 km). An estimate of the size of the parent meteor has been made from the observed magnitudes of these fragments. Assuming the parent meteoroid was spinning with an angular velocity between 100 and 1,000 rad s−1, an upper limit to the distance of breakup point from the Earth's surface can be placed at between 7 × 105 and 7 × 106 km (0.004–0.04 AU). We show here that the probabilities of collision and breakup of the parent Perseid with three classes of dust particle in near Earth space—interplanetary, magnetospheric and lunar ejecta—at the time of our observation in 1977, were ∼3 × 10−6, 3 × 10−6 and 5 × 10−7 respectively. We suggest therefore that if the Perseid parent comet (Swift–Tuttle) passes close to the Earth when it returns to perihelion in the next year or two, giving rise to a spectacular display of the Perseids, we should then be able to see many of these associated meteor events, and to study meteor collision with dust particles in near Earth space.

Diffusion, pericapillary distribution and clearance of Na-fluorescein in the human nailfold.

An intravital fluorescence videomicroscopy technique is described in an attempt to develop non-invasive methods for the study of transcapillary exchange in human physiology and clinical medicine. The apparatus used consists of a Ploemopak incident light fluorescence microscope and a low light level television camera with linear output. After intravenous bolus injection of Na-fluorescein in 12 healthy subjects the movement of the dye particles in the nailfold was observed and stored on video-tape. Immediately after arrival the dye leaks into a halo-like section and later into the more remote parts of the pericapillary space. By moving a densitometric window on an axis transversal to the capillary loop (single frames of the tape), characteristic patterns of fluorescent light intensity distribution were obtained at different time intervals. At the edge to the halo the high pericapillary light intensity decreases abruptly moving further away from the capillary (mean: 10.0 micron) for 20 min and more in each individual indicating the presence of a diffusion barrier at this location between halo and more remote areas. Clearance of the dye is much slower than transcapillary diffusion and lasts approximately 2 h.

A device that provides an eye-to-eye video perspective for interactive television

A device that allows individuals to engage in eye contact while interacting over two-way television is described. The apparatus consists of a television monitor and low light-level television camera housed within a cabinet containing a mirror system that resembles a combination beam splitter and periscope. Through the mirror system, the pick-up camera captures a reflected full-face eye-level image of the television viewer as he or she attends to the display monitor. The device is particularly useful for studying the nonverbal communication patterns of individuals engaged in social interaction.

AUTOMATIC PASSIVE LOW LIGHT LEVEL TELEVISION GUN‐DIRECTOR RANGEFINDER

ABSTRACTOn many Navy ships, gunnery is directed and controlled using radar and stereoscopic optical rangefinders. Radar is rapid, automatic, functional day and night, but is subject to limitations, especially at low angles of elevation. The stereoscopic optical rangefinder, because of its superior resolution, supplements radar with information on imagery and identification of target and gunnery accuracy through observation of the shell bursts relative to the target. Also, under Emission Control conditions, the passive rangefinder substitutes for radar. However, rangefinder usefulness is limited because 1) it requires sufficient daylight illumination and weather clarity, 2) there is a shortage of Fleet personnel with good stereoscopic perception, and 3) operator mechanical manipulation of the rangefinder optics makes it too slow for ranging on high‐speed aircraft.To improve the rangefinder utility, a passive day/night Low Light Level Television Rangefinder System has been proposed that will provide an image of the target and automatically display range in digital format on cathode ray tubes. Without modifying the stereoscopic range‐finder and with appropriate external optics, the range‐finder can be adapted to operate with the low light level television camera. Automatic ranging, which eliminates the operator, is obtained with new electronic TV time‐scanning circuitry which will provide rapid, continuous digital range. Ranging on high‐speed aircraft will be possible.The gun‐director rangefinder is, at times, used for general navigation, collision avoidance, stationkeeping, surveillance, etc. The Low Light Level Television Range‐finder System will provide night and automatic ranging capabilities for these applications.