Video detection

The eombination in a compact system of an infrared sensor and a laser as excitation source is called a photothermal camera. The surface heating is aehieved by the absorption of the focused beam of a laser. This localisation of the heating permits a three-dimensional heat diffusion in the sample to be examined. The infrared (IR) emission of the surface in the neighbourhood of the heating spot is measured by an infrared detector. A full surface inspection is possible through a video scanning of the excitation and detection spots on the piece to test (figure 1). 

Whereas scintillation screens can be used to directly view x-rays passing through the body, the dose to a patient is too high. Instead, scintillation screens are combined with video cameras or electronic intensifier tubes and video cameras. This detection scheme is used in digital radiography where digital x-ray images are recorded, and fluoroscopy where temporal processes are to be followed. 

Most CCDs are specifically designed for video camera apphcations, which detect photons in the visible portion of the electromagnetic spectra. 

Response to Electric and Acoustic Fields. If the stabilization of a suspension is primarily due to electrostatic repulsion, measurement of the zeta potential, can detect whether there is adequate electrostatic repulsion to overcome polarizabiUty attraction. A common guideline is that the dispersion should be stable if > 30 mV. In electrophoresis the appHed electric field is held constant and particle velocity is monitored using a microscope and video camera. In the electrosonic ampHtude technique the electric field is pulsed, and the sudden motion of the charged particles relative to their counterion atmospheres generates an acoustic pulse which can be related to the charge on the particles and the concentration of ions in solution (18). 

To date, the usual way of recording the LEED pattern is a light-sensitive video camera with a suitable image-processing system. In older systems movable Earaday cups (EC) were used which detected the electron current directly. Because of long data acquisition times and the problems of transferring motion into UHV, these systems are mostly out of use nowadays. 

In that pioneering study28 it was not possible to obtain a time resolved distribution of the backspillover oxygen species despite the fast, 40 ms, time resolution of the video-frames. If the spillover distance is 100 pm, this implies surface spillover oxygen diffusivities as high as 10 3 cm2/s. If, however, microcracks exist in the film, which is very likely, then the spillover distance is much shorter and thus much lower diffusivities would suffice to escape time-dependent detection. 

An endoscope, coupled with video rate wide field imager, operating in either the time or frequency domain [92] could be an invaluable tool for early detection of cancer or possibly other diseases whose AF signatures are yet to be studied. 

Free-standing sensors—These sensors, which include active infrared, passive infrared, bistatic microwave, monostatic microwave, dual-technology, and video motion detection (VMD) sensors, consist of individual sensor units or components that can be set up in a variety of configurations to meet a user s needs. They are installed aboveground, and depending on how they are oriented relative to each other, they can be used to establish a protected perimeter or a protected space. More details on each of these sensor types are provided below. 

J. Summanen, T. Yrjonen, R. Hiltunen and H. Vuorela, Influence of densitometer and video documentation settings in the detection of plant phenolics by TLC. J. Plan. Chromatogr.— Mod. TLC 11 (1998) 421 127. 

Factors making such patterns hidden to the naked eye are illustrated and a computer algorithm is described for pattern detection essentially through 1) wild pattern growth based on the detection of critical interval relations between pairs of time point series 2) pattern competition and 3) pattern selection. The corresponding theme software provides in addition multimedia techniques for data collection and interactive inspection of detected patterns in digitized video (avi). 

Surveillance technology can be divided into general categories video surveillance, tracking, illumination, and telescopic and detection devices. The technical developments in each method have been dramatic. 

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