Pulse Shape Measurement Using Golay Detector
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Pulse Shape Measurement Using Golay Detector A. K. Kaveev & E. G. Kaveeva & E. A. Adaev
Received: 2 December 2011 / Accepted: 2 February 2012 / Published online: 28 February 2012 # Springer Science+Business Media, LLC 2012
Abstract The article discusses key physical processes within the active area of an optoacoustic detector. Said area is a xenon-filled chamber subdivided into two cavities connected by a narrow channel. Original mathematical model of such area is proposed on the basis of thermodynamic processes that occur within. A method has been developed to measure a shape of a periodic pulse exceeding 0.5 ms duration at repetition rates ranging from zero to several hundred Hz. The measurement requires knowledge of a set of parameters describing a specific instrument. Principal points of detector calibration are discussed in brief. Keywords Golay cell . Pulse shape measurement
1 Introduction Photo-acoustic spectroscopy of gases and solid phases, possibility of that was discovered by Bell, was developed by Rosencwaig and others in 1980-th [1–6]. Also photo-acoustic imaging was developed [7]. Very good review of photo-acoustic devices in appliance to spectroscopy one may find in PhD thesis of Kavaya [8]. Some works (for example, [4, 8– 10]) were devoted to mathematical model of photo-acoustic detector development. Nevertheless, nobody has applied any such method to Golay cell. The constructions of photoacoustic detectors (OADs) used in spectroscopy imply relatively large (in compare to Golay cell) gas chamber where pressure (i.e. acoustic) waves propagate and resonant properties of the gas are important because of spectroscopic application for example, [11] in contrast to Golay cell. Model of Rosengren implies pressure front calculation from close to rectangular input pulse series, in approach of constant gas concentration, and taking into account resonant properties of the pressure wave. The problem of calculation of input wave from known pressure change was not solved. Also variations of gas density (that is critical for Golay cell behavior description) were not implied. A. K. Kaveev (*) : E. A. Adaev Tydex J. S. Co., 16 Domostroitelnaya str., 194292 St. Petersburg, Russia e-mail: [email protected] E. G. Kaveeva St.Petersburg State Polytechnical University, 29 Polytechnicheskaya str., 195251 St.Petersburg, Russia
J Infrared Milli Terahz Waves (2012) 33:306–318
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Apart of gas-based opto-acoustic detectors there are other types of OADs. For example, high power THz and RF opto-acoustic detector based on liquid state [12] was developed in last years. Nevertheless, in all cases opto- (or photo-) acoustic method of measurement is based on the same principle: transformation of optical wave into acoustic one and detection of the last. Golay cell is based on a design first introduced by M. J. E. Golay in 1947 [13, 14]. Key features that enable efficient usage of the detector in various applications include its small size, operability at room temperature, high sensitivity, high efficiency and wide operating wa
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