In the measurement of deformation of buckling phenomenon, the optical measurement methods have been traditionally employed for performing noncontact measurement. Furthermore, because the in-plane and out-of-plane deformations simultaneously happen in the buckling phenomena, these in-plane and out-of-plane deformations must be separated precisely by analyzing some measured results of dynamic events. In traditional methods, some two-beam interferometers have been combined to measure in-plane and out-of-plane deformations as three-dimensional deformations. An ordinary two-beam interferometer is defined as the optical system that is combined by two independent interferometers. Under this definition, a new interferometer that is set up by two cameras and one laser is constructed by using the idea of a speckle interferometer that uses only two speckle patterns. Then, an analysis method for separation of in-plane and out-of-plane deformations is also proposed. In the experimental results, the high measuring accuracy of the proposed methods is confirmed. Consequently, the independency between in-plane and out-of-plane measurements in this method is confirmed. Furthermore, the new method is applied to the analysis of the buckling phenomenon. As the results, it can be confirmed that the results of the beam of buckling analysis agree very well with the theory of Euler’s buckling.