Working standard of units of length, speed, and acceleration in vibratory motion of solids

Abstract

UDC 53.089.68:531.3 At the All-Union Research Institute of Gauges and Standards (VNIIMS) a working standard (WS) of units of length, speed, and acceleration in vibratory motion of solids was devised; it is intended for checking reference and accurate working means of measuring vibration parameters [i ]. The introduction of this instrument in checking practice will make it possible to use methods of checking and calibration on a broader scale; these methods are based on measuring the amplitude of translation by direct comparison with the wavelength of laser radiation, and thereby they improve the level of metrological provisions in the field of vibrometry. The working standard is a complex of means of presetting mechanical vibrations, and also of measuring the amplitude and frequency of these vibrations. In accordance with the government checking arrangement [i] the WS has the following technical and metrological characteristics: range of vibratory translation 2.0"10-8-5.0"10 -3 m; range of vibratory speeds 1.0"i0-~-i.0"i0 -l m/sec; range of vibratory accelerations 1.0-10-3-5.0"103 m/sec2; total error SZ, determined by the rms deviation of the result of measurement in the comparison of WS with a primary standard and by the noneliminated systematic error, no more than 5.0"10 -3 in the frequency range 2.0-10 -I- 1.0-i0 s Hz and no more than 1.5"10 -2 in the frequency ranges 3.0"10-i-2.0"101 and 1.0"i03-2.0"i0 ~ Hz. The following serve as means of presetting the mechanical vibrations: a piezoelectric vibrator in the range of amplitudes of vibratory translations 2.0"i0-s-2.0"i0 -7 m and of frequencies 3.0"i0-i-2.0"I04 Hz, an electrodynamic vibrator in the range of amplitudes of vibratory translations 2.0"10-7-5.0"10 -3 m and frequencies 3.0"10-I-103 Hz, a tuning fork vibrator in the range of amplitudes of vibratory accelerations up to 5.0"103 m/sec 2 at the frequency of 1.35"103 Hz. The amplitude of the vibratory translations is measured with the aid of two small twoway and one multiway laser interferometers. The former two operate jointly with the electrodynamic and the tuning fork vibrators, the latter with the piezoelectric vibrator. The measurement of small and ultrasmall vibrations is based on the method of "zeros" of a Bessel function, which in turn is a modification of the method of narrow-band filters. Amplitudes of translation above 0.2 ~m are determined by the method of counting interference bands. We will deal with each of the mentioned methods of measurement. The method of counting interference bands. In the WS two modifications of the mentioned method are realized: the method of unidirectional count and the method using a frequency meter. It is known [2] that the double amplitude of the vibrations 2S0 in measurements by the method of unidirectional count is correlated with the number of interference bands by the relation