Scanning systems

N.Nielsen, P-scan system for ultrasonic weld inspection . The Danish Welding Institute, 1980. 

The introduction of automated scanning systems was a great leap forward in the development. That way, the uncertainties of manual probe guidance were eliminated. Usually, these systems were designed for high-frequency surface tests and followed the outer profile of the surface with a probe that could be moved in several axes. A continuous 100 % scan became possible and, as a result, the documentation of the tests with stripchart recorders suggested itself. Now for the first time, wheel testing became retraceable. 

Illustration Automatic Wheel-Scanning System Improvements of the Test Situation ... 

The P-scan System 4 design specifications further included a number of performance and functionality improvements. 

These design specifications have all been met in the realization of the new P-scan System 4 concept. 

The P-scan System 4 can be configured in many ways, dependent on the application. Figure 1 shows a basic system configuration. The P-scan processor (PSP-4) controls the scanner and the water pump. Scarmer operation on site is performed from the remote control unit, as an alternative to the control from the computer. The PSP-4 also includes the ultrasonic system. 

Computerised Ultrasonic Testing of Constructions which are Past their Service Life, Based on P-SCAN System. 

The computerised ultrasonic P-scan system (FORCE Institute, Denmark) has been in operation in Ukraine since 1992. Over this period rather extensive new technological experience has been accumulated of solving the complicated tasks of reliability of the constructions the design life of which is over. 

However, if the probe is used as linear scanning system, the acoustic beam depends on the element characteristics which are liable to change from one element to an other. Therefore, the only two alternative proposals are to characterise the aeoustie behaviour of all active sub-set of elements or to proeeed to a statistical characterization. 

The sample frequency of the ADC (analogue to digital converter) should be 8 times higher than the test frequency (centre frequency of the spectrum). In dependence of the application, different ADC- boards are used. A standard board (20520) provides 8 bit resolution and up to 100 Msamples/s in single shot mode. For manual tests, up to 400 Msamples/s can be reached in the repetition mode. For scanning systems with high frequencies boards up to 400 Msamples/s (single shot) are available. 

The software US-SCAN 3.0 (IBT GmbH, Ober-Ramstadt, Germany) provides all functions of a portable flaw detector and a powerful ultrasonic imaging in A-, B-, C- and D-scans. Not only motor driven scanners can he used, but also manual scanning systems with encoders. Further documentation and test reports can be carried out with Windows software. 

P-Scan System 4 Ultrasonic Data Acquisition System... 

The principal equipment for the ultrasonic examination is the P-scan system, PS-4, which is a computerised ultrasonic system, developed by FORCE Institute, for automatic, mechanical and manual ultrasonic examination of welds and materials. The system has documentation and storage facilities for all data related to each inspection operation, and includes visualisation of the inspection results in the form of images of the material volume examined. 

SCANNING SYSTEM FOR TUBE MEASUREMENT DURING DRAWING... 

Based on the results from the initial experiments ultrasonic equipment and transducers for the scanning system were selected. Also a measuring chamber with transducer fixtures was constructed and manufactured for measurement on the tubes directly on the drawing bench. 

Measurement at 500 m/min was considered so promising that it was decided to manufacture and test a prototype for the four channel scanning system. In such a system multiplexing of signals from the four transducers to one ultrasonic instrument was a possibility. Alternatively four independent instruments (one for each transducer) could be used in the scanning system. 

The four channel scanning system showed stable measurements up to 250 m/min drawing speed. At 300-350 m/min some measurements were unstable on two channels. At drawing velocities over 350 m/min measurements were unstable on all four channels. The four traces are better identified in colors on the computer screen than in this grey tone figure. 

The scanner has been constructed in modules which, for future applications, makes it easy to increase the length of the scanner for inspection of larger blades, by adding further modules to the system. In co-operation with LM Glasfiber and RIS0 it was decided to construct the first scatmer for inspection of blades with a length of max. 21m. In order to be able to scan primarily the bonded areas from the root to the tip of the rotor blade, a so-called X-unit module was constructed. The movement from the root to the tip of the blade was controlled by the P-scan system. 

The coin-tap test is a widely used teclinique on thin filament winded beams for detection of disbonded and delaminated areas. However, since the sensitivity of this teclinique depends not only on the operator but also on the thickness of the inspected component, the coin-tap testing technique is most sensitive to defects positioned near the surface of the laminate. Therefore, it was decided to constructed a new scaimer for automated ultrasonic inspection of filament winded beams. A complete test rig illustrated in figure 6 was constructed in order to reduce the scanning time. While the beam rotates the probe is moved from one end to the other of the beam. When the scarming is complete it is saved on diskette and can then be evaluated on a PC. The scanner is controlled by the P-scan system, which enables the results to be presented in three dimensions (Top, Side and End view). 

Ion Implantation Systems. An ion implantation system is used to accelerate ionized atomic or molecular species toward a target sample. The ionized species penetrates the surface of the sample with the resulting depth profile dependent on the implanted species mass, energy, and the sample target s tilt and rotation. An implanter s main components include an ionizer, mass separator, acceleration region, scanning system, and sample holder (168). 

With the advent of computerized real-time systems, the distinction between continuous and periodic condition monitoring must be modified. Though technically periodic, a scanning system operating fast enough to protect against catastrophic failure is considered continuous. Most people consider one second or faster scan rates as continuous. A scan rate of one second is defined as monitoring each point once each second. 

The argument that an analog system dedicated to each measurement parameter provides better protection than a scanning system simply is not true. An analog system has inherent time delays that result in finite... 

Direct-reading polychromators (Figure 3b) have a number of exit slits and photomultiplier tube detectors, which allows one to view emission from many lines simultaneously. More than 40 elements can be determined in less than one minute. The choice of emission lines in the polychromator must be made before the instrument is purchased. The polychromator can be used to monitor transient signals (if the appropriate electronics and software are available) because unlike slew-scan systems it can be set stably to the peak emission wavelength. Background emission cannot be measured simultaneously at a wavelength close to the line for each element of interest. For maximum speed and flexibility both a direct-reading polychromator and a slew-scan monochromator can be used to view emission from the plasma simultaneously. 

Fig. 3.83. Potentiometric dead-stop (1) and reversed dead-stop (2) end-point titrations, (a) Metrohm Polarecord 626 PARC Model 174A Polarographic Analyzer, (b) Radiometer ISS 820 Ion Scanning System, (c) Tacussel PRG4 Polarograph. 

Implementation of time domain FLIM methods is comparatively straightforward in laser scanning microscopes (LSMs). Here, pointscanning is used so that single channel lifetime detection suffices. In principle, standard fluorescence lifetime detection equipment developed for spectroscopy can be used in combination with point-scanning systems and a pulsed laser. 

These workers used a radiometer ISS 820 ion-scanning system [101,321-323] equipped with a glassy carbon electrode to determine copper at the 2-200 xg/l level in nitrogen-purged 0.45 pm Millipore-filtered seawater to which had been added 5 ppm mercury. 

SABRE 2000 The portable SABRE 2000, using a scanning system based on IMS (Ion Mobility Spectrometry) can detect drugs, explosives, and chemical warfare agents. More than forty substances can be simultaneously detected and identified in seconds. 

Avilov A.S., Kuligin, A.K., Pietsch, U., et al. Scanning System for High Energy Eleetron Diffraction. J.Appl.Cryst. (1999), 32, 1033. 

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