A membrane deflection technique has been developed to measure the isot
ropic residual stress in biaxially-constrained coatings. The technique
has been demonstrated on various materials, including polyimide, late
x rubber and photoresist coatings. Stress values obtained from membran
e deflection compared well with results obtained from time-averaged vi
brational holographic interferometry except for values obtained from s
amples where rigidity effects were found to be important. A criterion
based on the thickness, rigidity, stress and sample radius is also dis
cussed, establishing the applicability of the technique to samples of
low rigidity.