Experimental problems with laser interferometric measurements of piezoelect
ric response are examined. Theoretical analysis of the sources of systemati
c errors and inaccuracies was done in order to set the limits for both sing
le and double beam interferometers. It appears that some of the published r
esults of electric-field induced displacements of order 10(-12) m are probl
ematic. It is discussed in the paper which corrections must be taken into a
ccount and which experimental conditions must be mentioned. A new laser int
erferometer was set up on the basis of these conclusions.