Spectrum analyzer

About: Spectrum analyzer is a research topic. Over the lifetime, 12217 publications have been published within this topic receiving 101851 citations.

UCL multichannel time-resolved system for optical tomography

Abstract: A multichannel time resolved imaging system is being developed at University College London (UCL) suitable for optical tomography of the human breast and neonatal brain. The system utilizes the time correlated single photon counting technique, operating in reverse start-stop mode. The detectors are custom made multi-anode microchannel plate photomultipliers (Hamamatsu R411OU-05MOD). Signal processing is implemented using fast NIM logic, and the system is based upon the ORTEC 9308-D picosecond time analyzer in place of a conventional time to amplitude converter. The system is designed to acquire 32 channels of time-resolved data simultaneously, with sub-100 ps temporal resolution, and at count rates of at least 2 multiplied by 104 photons per second per channel. This paper discusses the theoretical considerations which led to the final design, and describes the detector and electronic hardware on which the system is based.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Modified quadrupole mass analyzer RGA-100 for beam plasma research in forevacuum pressure range

Abstract: The industrial quadrupole RGA-100 residual gas analyzer was modified for the research of electron beam-generated plasma at forevacuum pressure range. The standard ionizer of the RGA-100 was replaced by three electrode extracting unit. We made the optimization of operation parameters in order to provide the maximum values of measured currents of any ion species. The modified analyzer was successfully tested with beam plasma of argon, nitrogen, oxygen, and hydrocarbons.

Method and apparatus for nondisruptively measuring line impedance at frequencies which are relatively close to the line frequency

Abstract: Impedance of an energized electrical line which carries electrical current at a predetermined line frequency is nondistruptively measured at frequencies which are above and below the predetermined line frequency. A measurement current is generated at a measurement frequency between, for example, 10 Hz and 30 kHz for a 60 Hz line. The current generator is coupled to the energized electrical line by an isolating circuit which blocks only the predetermined line frequency and frequencies which differ from the predetermined line frequency by substantially less than the predetermined line frequency. For example, a notch filter may be used. A current sensor measures the line current in the energized line at the measurement frequency. A voltage sensor measures the line voltage in the energized electrical line at the measurement frequency. An analyzer determines impedance of the energized line at the measurement frequency. The measurement is repeated over a wide range of frequencies above and below the line frequency. Preferably, the current sensor and voltage sensor use the same current sensor to cancel errors. Improved nondisruptive line impedance measuring is thereby provided.

A multi-detector system for a triple-axis spectrometer

Abstract: Until now there have been only a few attempts to use many scattering angles simultaneously in triple-axis spectrometry with neutrons. We present a novel Multi-Analyzer Detector (MAD) unit for a Triple-Axis Spectrometer (TAS) set up at the Forschungsreaktor Munchen (FRM). The layout is based on the principle of monochromatic defocusing. Up to 61 analyzers are mounted around the sample in the constant final energy mode. This arrangement supplies the flexibility of a TAS with a multi-channel analyzer capacity similar to a Time-of-Flight Spectrometer. The gain in measurement time can be more than an order of magnitude.

Infrared, multiple gas analyzer and methods for gas analysis

Abstract: A portable, infrared, multiple gas analyzer for measuring the concentration of a plurality of infrared absorbent gases with a simple optical arrangement for transmitting an infrared beam along an optical path along with gas mixtures to be analyzed. Light transmitting tubes arranged in a U-like configuration transmit infrared energy and the gases applied thereto over a small path to an infrared detector from an infrared source and provide electrical analog output signals representative of the detected gases. The detector output signals are processed by D.C. processing circuits including an analog to digital converter and microprocessing circuits for providing digital, binary coded, output signals representative of the detected gas concentration of the infrared absorbent gases. The analyzer can be readily calibrated by applying a non-infrared absorbent gas to the gas analyzer to provide a maximum output signal level with the infrared beam on and the background level or dark level signal with the beam off. The gas mixture having the infrared absorbent gases to be measured are applied to the analyzer for measurement and the resulting analog signals are amplified under control of a microprocessor for determining whether or not a preselected signal level stored in the microprocessor memory is exceeded or not. If not, the gain of the amplifier is increased to compensate for the aging of the analyzer. An offset voltage is applied to the analog to digital converter under control of the microprocessor to the amplified gas signals for increasing the resolution of the converter output signals only during the time intervals the absorbent gases are being measured. The microprocessor is programmed to execute a program for calculating the detected concentration of the gases undergoing analysis based on the previously acquired and stored “zero” gas level, dark level and known gas factors to provide the desired digital, binary coded, gas concentration signal from the analyzer.