Overcoming Pitfalls When Measuring Thin, Parallel Optics

Driven by the demand for smaller and smaller consumer products and semiconductor devices, manufacturers require thin planar optics for an array of applications. This puts the responsibility on the material and optics manufacturers to ensure the surface of the glass is flat and free of material deformities which can cause distortion and affect end-use functionality. One advanced solution is Fourier-transform phase-shifting interferometry (FTPSI), which enables easy characterization of the front and back surface, optical thickness variation, and material homogeneity of thin plane parallel glass.