We analyze interaction-free measurements in cavity resonators. We study bot
h classical objects and quantum objects: two-level atoms strongly coupled t
o a cavity mode. We also discuss complementarity in interaction-free measur
ement. (C) 1998 Optical Society of America [S0740-3224(98)00110-6] OCIS cod
es: 270.0270, 270.5570, 270.5580.