Page 8 - ДисМокрий21
P. 8

8


               radiation is performed, and it is shown that it corresponds to the displacement of the

               surface of the object under the action of surface acoustic wave (SAW). The value of

               the optical beam spot width on the surface of the control object is also analyzed for

               the effectiveness of the proposed method. It has been experimentally shown that its

               width should be relatively  greater than 3Λ, and  Λ is the  length  of the SAW.  Also

               considered are limitations on the  magnitude of optical beam expansion that can be

               used effectively in this technique. Based on the analysis of the optical field, I also the

               width of the spot of the optical beam shows that the proposed method can be applied

               in  the  frequency  range  1  -  15  MHz.  Techniques  for  determining  the  speed  of  the

               SAW  by  the  extended  beam  method,  which  does  not  move  the  photodetector,  are

               offered, which makes it possible to simplify the measurements and to avoid errors in

               determining the position of the photodetector.

                     A  new  simple  technique  for  stabilizing  the  operation  of  the  Michelson

               interferometer under vibration and temperature drift is proposed. Stabilization of the

               interferometer is achieved due to the formation of the interference pattern in the form

               of  parallel  interference  bands  on  the  surface  of  the  photodetector.  A  numerical

               simulation of the proposed stabilization scheme is performed and it is shown that the

               most effective geometry is the width of the interference line being equal to the length

               of  the  SAW  mapping  to  the  plane  of  the  sensitive  area  of  the  photodetector.  An

               experimental study of the proposed stabilization scheme showed its effectiveness in

               the case when the optical beam radius exceeds several SAW lengths.

                     Methods  for  reducing  the  inaccuracy  of  the  SAW  rate  of  a  piezoelectric

               transducer  have  been  developed  in  which  the  excitation  and  recording  prisms  are

               rigidly connected. The influence of the temperature change of the converter on the

               error of measuring the velocity of the SAW is analyzed. A method of minimizing the

               temperature error of speed measurement by compensating for the temperature change

               of linear dimensions by the temperature change of the velocity of the acoustic waves

               of  the  transducer  elements  is  proposed.  The  effect  of  the  depth  on  the  transducer


               surface on the measurement of the SAW rate is also considered for the first time. It is
   3   4   5   6   7   8   9   10   11   12   13