A noncontacting method for measuring mechanical strain between two fid
ucial marks has been developed for use when environmental conditions w
ould be disruptive to methods utilizing optical light. A silicon 111 J
ohansson crystal is used for this application when Mo K alpha radiatio
n is used to fluoresce fiducial markers made of yittria-stabilized zir
conia, This substance is used for a thermal barrier costing in gas tur
bine engines and the technology for applying this material to withstan
d long term high temperature exposure is highly developed. The current
system has a displacement repeatability of better than 0.1 mu m which
is not limited by counting statistics, but rather determined by mecha
nical considerations. (C) 1998 American Institute of Physics.