A method of visualization of phase changes in two-dimensional pure-phase objects by use of two orthogonal Fourier plane filters that realize the half-order differentiation is presented. Real semiderivative filters used in two dimensions and in sequence yield output-image intensity signals proportional to the first derivatives of the input-object phase that appear on a constant background. This nonlinear filtration of spatial frequencies permits the alleviation of the consequences of square-law detection and makes phase changes visible. Phase changes in gradient-index phosphate glass are calculated experimentally. We discuss the accuracy of the proposed method.
© 1998 Optical Society of America
(070.0070) Fourier optics and signal processing : Fourier optics and signal processing
(070.1170) Fourier optics and signal processing : Analog optical signal processing
(070.2580) Fourier optics and signal processing : Paraxial wave optics
(070.4560) Fourier optics and signal processing : Data processing by optical means
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
Tomasz Szoplik, Vicent Climent, Enrique Tajahuerce, Jesús Lancis, and Mercedes Fernández-Alonso, "Phase-Change Visualization in Two-Dimensional Phase Objects With a Semiderivative Real Filter," Appl. Opt. 37, 5472-5478 (1998)